141-462: Comparative anatomy is the study of similarities and differences in the anatomy of different species . It is closely related to evolutionary biology and phylogeny (the evolution of species). The science began in the classical era , continuing in the early modern period with work by Pierre Belon who noted the similarities of the skeletons of birds and humans. Comparative anatomy has provided evidence of common descent , and has assisted in
282-412: A basal lamina , the upper layer of the basement membrane , the lower layer is the reticular lamina lying next to the connective tissue in the extracellular matrix secreted by the epithelial cells. There are many different types of epithelium, modified to suit a particular function. In the respiratory tract there is a type of ciliated epithelial lining; in the small intestine there are microvilli on
423-450: A copulatory organ present in most species. The eggs are surrounded by amniotic membranes which prevents them from drying out and are laid on land, or develop internally in some species. The bladder is small as nitrogenous waste is excreted as uric acid . Turtles are notable for their protective shells. They have an inflexible trunk encased in a horny carapace above and a plastron below. These are formed from bony plates embedded in
564-481: A microscope . Human anatomy, physiology and biochemistry are complementary basic medical sciences, which are generally taught to medical students in their first year at medical school. Human anatomy can be taught regionally or systemically; that is, respectively, studying anatomy by bodily regions such as the head and chest, or studying by specific systems, such as the nervous or respiratory systems. The major anatomy textbook, Gray's Anatomy , has been reorganized from
705-470: A sessile lifestyle). Most animals have bodies differentiated into separate tissues and these animals are also known as eumetazoans . They have an internal digestive chamber, with one or two openings; the gametes are produced in multicellular sex organs, and the zygotes include a blastula stage in their embryonic development . Metazoans do not include the sponges , which have undifferentiated cells. Unlike plant cells , animal cells have neither
846-402: A "treatise on the heart", with vessels carrying all the body's fluids to or from every member of the body. Ancient Greek anatomy and physiology underwent great changes and advances throughout the early medieval world. Over time, this medical practice expanded due to a continually developing understanding of the functions of organs and structures in the body. Phenomenal anatomical observations of
987-400: A T lymphocytes or a thymocytes) are immune cells that grow from stem cells in the bone marrow. They assist to defend the body from infection and may aid in the fight against cancer. Because of their morphological, physiological, and genetic resemblance to humans, mice and rats have long been the preferred species for biomedical research animal models . Comparative Medicine Research is built on
1128-583: A basis for finding antigens that result in immune response against pathogenic strains but not commensal ones. In May 2019, using the Global Genome Set, a team in the UK and Australia sequenced thousands of globally-collected isolates of Group A Streptococcus , providing potential targets for developing a vaccine against the pathogen, also known as S. pyogenes . Personalized Medicine Personalized Medicine , enabled by Comparative Genomics, represents
1269-528: A cell wall nor chloroplasts . Vacuoles, when present, are more in number and much smaller than those in the plant cell. The body tissues are composed of numerous types of cells, including those found in muscles, nerves and skin. Each typically has a cell membrane formed of phospholipids , cytoplasm and a nucleus . All of the different cells of an animal are derived from the embryonic germ layers . Those simpler invertebrates which are formed from two germ layers of ectoderm and endoderm are called diploblastic and
1410-418: A cellular organism, that of Haemophilus influenzae Rd, was published in 1995. The second genome sequencing paper was of the small parasitic bacterium Mycoplasma genitalium published in the same year. Starting from this paper, reports on new genomes inevitably became comparative-genomic studies. Microbial genomes. The first high-resolution whole genome comparison system of microbial genomes of 10-15kbp
1551-433: A class of arachnids have four pairs of legs; a body of two segments—a cephalothorax and an abdomen . Spiders have no wings and no antennae. They have mouthparts called chelicerae which are often connected to venom glands as most spiders are venomous. They have a second pair of appendages called pedipalps attached to the cephalothorax. These have similar segmentation to the legs and function as taste and smell organs. At
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#17327880244101692-552: A coat of glycoproteins . In more advanced animals, many glands are formed of epithelial cells. Muscle cells (myocytes) form the active contractile tissue of the body. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle is formed of contractile filaments and is separated into three main types; smooth muscle , skeletal muscle and cardiac muscle . Smooth muscle has no striations when examined microscopically. It contracts slowly but maintains contractibility over
1833-430: A common ancestor. It also assists scientists in classifying organisms based on similar characteristics of their anatomical structures. A common example of comparative anatomy is the similar bone structures in forelimbs of cats, whales, bats, and humans. All of these appendages consist of the same basic parts; yet, they serve completely different functions. The skeletal parts which form a structure used for swimming, such as
1974-514: A detailed examination of CNVs and their significance. When investigators examined the raw sequence data of the human and chimpanzee. Comparative genomics holds profound significance across various fields, including medical research, basic biology, and biodiversity conservation. For instance, in medical research, predicting how genomic variants limited ability to predict which genomic variants lead to changes in organism-level phenotypes, such as increased disease risk in humans, remains challenging due to
2115-463: A few species have no limbs and resemble snakes. Lizards have moveable eyelids, eardrums are present and some species have a central parietal eye. Snakes are closely related to lizards, having branched off from a common ancestral lineage during the Cretaceous period, and they share many of the same features. The skeleton consists of a skull, a hyoid bone, spine and ribs though a few species retain
2256-446: A fin, would not be ideal to form a wing, which is better-suited for flight. One explanation for the forelimbs' similar composition is descent with modification. Through random mutations and natural selection, each organism's anatomical structures gradually adapted to suit their respective habitats. The rules for development of special characteristics which differ significantly from general homology were listed by Karl Ernst von Baer as
2397-418: A gene exists in the original species, the species divided into two species, so genes in new species are orthologous to the sequence in the original species. Paralogous sequences are separated by gene cloning (gene duplication): if a particular gene in the genome is copied, then the copy of the two sequences is paralogous to the original gene. A pair of orthologous sequences is called orthologous pairs (orthologs),
2538-760: A global strategy. Additionally, ongoing efforts focus on optimizing existing algorithms to handle the vast amount of genome sequence data by enhancing their speed. Furthermore, MAVID stands out as another noteworthy pairwise alignment program specifically designed for aligning multiple genomes. Pairwise Comparison: The Pairwise comparison of genomic sequence data is widely utilized in comparative gene prediction. Many studies in comparative functional genomics lean on pairwise comparisons, wherein traits of each gene are compared with traits of other genes across species. his method yields many more comparisons than unique observations, making each comparison dependent on others. Multiple comparisons: The comparison of multiple genomes
2679-742: A greater role in evolutionary change compared to single nucleotide changes. Research indicates that CNVs affect more nucleotides than individual base-pair changes, with about 2.7% of the genome affected by CNVs compared to 1.2% by SNPs. Moreover, while many CNVs are shared between humans and chimpanzees, a significant portion is unique to each species. Additionally, CNVs have been associated with genetic diseases in humans, highlighting their importance in human health. Despite this, many questions about CNVs remain unanswered, including their origin and contributions to evolutionary adaptation and disease. Ongoing research aims to address these questions using techniques like comparative genomic hybridization , which allows for
2820-513: A high metabolic rate , a light skeletal system and powerful muscles . The long bones are thin, hollow and very light. Air sac extensions from the lungs occupy the centre of some bones. The sternum is wide and usually has a keel and the caudal vertebrae are fused. There are no teeth and the narrow jaws are adapted into a horn-covered beak. The eyes are relatively large, particularly in nocturnal species such as owls. They face forwards in predators and sideways in ducks. The feathers are outgrowths of
2961-617: A major source of genetic diversity , influencing gene structure , dosage , and regulation . While single nucleotide polymorphisms (SNPs) are more common, CNVs impact larger genomic regions and can have profound effects on phenotype and diversity. Recent studies suggest that CNVs constitute around 4.8–9.5% of the human genome and have a substantial functional and evolutionary impact. In mammals, CNVs contribute significantly to population diversity, influencing gene expression and various phenotypic traits . Comparative genomics analyses of human and chimpanzee genomes have revealed that CNVs may play
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#17327880244103102-746: A mammal. Humans have a head, neck, trunk (which includes the thorax and abdomen ), two arms and hands, and two legs and feet. Generally, students of certain biological sciences , paramedics , prosthetists and orthotists, physiotherapists , occupational therapists , nurses , podiatrists , and medical students learn gross anatomy and microscopic anatomy from anatomical models, skeletons, textbooks, diagrams, photographs, lectures and tutorials and in addition, medical students generally also learn gross anatomy through practical experience of dissection and inspection of cadavers . The study of microscopic anatomy (or histology ) can be aided by practical experience examining histological preparations (or slides) under
3243-496: A number of branches, including gross or macroscopic anatomy and microscopic anatomy. Gross anatomy is the study of structures large enough to be seen with the naked eye, and also includes superficial anatomy or surface anatomy, the study by sight of the external body features. Microscopic anatomy is the study of structures on a microscopic scale, along with histology (the study of tissues), and embryology (the study of an organism in its immature condition). Regional anatomy
3384-760: A pair of paralogous sequence is called collateral pairs (paralogs). Orthologous pairs usually have the same or similar function, which is not necessarily the case for collateral pairs. In collateral pairs, the sequences tend to evolve into having different functions. Comparative genomics exploits both similarities and differences in the proteins , RNA , and regulatory regions of different organisms to infer how selection has acted upon these elements. Those elements that are responsible for similarities between different species should be conserved through time ( stabilizing selection ), while those elements responsible for differences among species should be divergent ( positive selection ). Finally, those elements that are unimportant to
3525-420: A pump action in which air is first drawn into the buccopharyngeal region through the nostrils. These are then closed and the air is forced into the lungs by contraction of the throat. They supplement this with gas exchange through the skin which needs to be kept moist. In frogs the pelvic girdle is robust and the hind legs are much longer and stronger than the forelimbs. The feet have four or five digits and
3666-594: A recent common ancestor, the differences between the two species genomes are evolved from the ancestors' genome. The closer the relationship between two organisms, the higher the similarities between their genomes. If there is close relationship between them, then their genome will display a linear behaviour ( synteny ), namely some or all of the genetic sequences are conserved. Thus, the genome sequences can be used to identify gene function, by analyzing their homology (sequence similarity) to genes of known function. Orthologous sequences are related sequences in different species:
3807-620: A revolutionary approach in healthcare, tailoring medical treatment and disease prevention to the individual patient's genetic makeup. By analyzing genetic variations across populations and comparing them with an individual's genome, clinicians can identify specific genetic markers associated with disease susceptibility, drug metabolism , and treatment response. By identifying genetic variants associated with drug metabolism pathways, drug targets, and adverse reactions , personalized medicine can optimize medication selection, dosage, and treatment regimens for individual patients. This approach minimizes
3948-531: A root in the comparison of virus genomes in the early 1980s. For example, small RNA viruses infecting animals ( picornaviruses ) and those infecting plants ( cowpea mosaic virus ) were compared and turned out to share significant sequence similarity and, in part, the order of their genes. In 1986, the first comparative genomic study at a larger scale was published, comparing the genomes of varicella-zoster virus and Epstein-Barr virus that contained more than 100 genes each. The first complete genome sequence of
4089-444: A significant resource for supporting functional genomics and understanding how genes and intergenic regions of the genome contribute to biological processes. T-cell immune receptors are important in seeing the world of pathogens in the cellular immune system. One of the reasons for sequencing the human and mouse TCR loci was to match the orthologous gene family sequences and discover conserved areas using comparative genomics. These, it
4230-450: A single study. Comparative genomics has revealed high levels of similarity between closely related organisms, such as humans and chimpanzees, and, more surprisingly, similarity between seemingly distantly related organisms, such as humans and the yeast Saccharomyces cerevisiae . It has also showed the extreme diversity of the gene composition in different evolutionary lineages. See also : History of genomics Comparative genomics has
4371-543: A skeleton to support or protect the body. An exoskeleton is a thickened, rigid cuticle which is stiffened by mineralization , as in crustaceans or by the cross-linking of its proteins as in insects . An endoskeleton is internal and present in all developed animals, as well as in many of those less developed. Epithelial tissue is composed of closely packed cells, bound to each other by cell adhesion molecules , with little intercellular space. Epithelial cells can be squamous (flat), cuboidal or columnar and rest on
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4512-661: A specific gene on a chromosome (locs) and across species allow for research on other mechanisms and other regulatory signals. Some suggest new hypotheses about the evolution of TCRs, to be tested (and improved) by comparison to the TCR gene complement of other vertebrate species. A comparative genomic investigation of humans and mice will obviously allow for the discovery and annotation of many other genes, as well as identifying in other species for regulatory sequences. Comparative genomics also opens up new avenues in other areas of research. As DNA sequencing technology has become more accessible,
4653-497: A systems format to a regional format, in line with modern teaching methods. A thorough working knowledge of anatomy is required by physicians, especially surgeons and doctors working in some diagnostic specialties, such as histopathology and radiology . Academic anatomists are usually employed by universities, medical schools or teaching hospitals. They are often involved in teaching anatomy, and research into certain systems, organs, tissues or cells. Invertebrates constitute
4794-431: A vast array of living organisms ranging from the simplest unicellular eukaryotes such as Paramecium to such complex multicellular animals as the octopus , lobster and dragonfly . They constitute about 95% of the animal species. By definition, none of these creatures has a backbone. The cells of single-cell protozoans have the same basic structure as those of multicellular animals but some parts are specialized into
4935-479: A vertebrate is the vertebral column , formed in the development of the segmented series of vertebrae . In most vertebrates the notochord becomes the nucleus pulposus of the intervertebral discs . However, a few vertebrates, such as the sturgeon and the coelacanth , retain the notochord into adulthood. Jawed vertebrates are typified by paired appendages, fins or legs, which may be secondarily lost. The limbs of vertebrates are considered to be homologous because
5076-693: A vestige of the pelvis and rear limbs in the form of pelvic spurs . The bar under the second fenestra has also been lost and the jaws have extreme flexibility allowing the snake to swallow its prey whole. Snakes lack moveable eyelids, the eyes being covered by transparent "spectacle" scales. They do not have eardrums but can detect ground vibrations through the bones of their skull. Their forked tongues are used as organs of taste and smell and some species have sensory pits on their heads enabling them to locate warm-blooded prey. Crocodilians are large, low-slung aquatic reptiles with long snouts and large numbers of teeth. The head and trunk are dorso-ventrally flattened and
5217-420: A well annotated reference genome, and thus provide a list of possible gene differences that may be the basis for any functional variation among strains. One character of biology is evolution, evolutionary theory is also the theoretical foundation of comparative genomics, and at the same time the results of comparative genomics unprecedentedly enriched and developed the theory of evolution. When two or more of
5358-594: A wide range of stretch lengths. It is found in such organs as sea anemone tentacles and the body wall of sea cucumbers . Skeletal muscle contracts rapidly but has a limited range of extension. It is found in the movement of appendages and jaws. Obliquely striated muscle is intermediate between the other two. The filaments are staggered and this is the type of muscle found in earthworms that can extend slowly or make rapid contractions. In higher animals striated muscles occur in bundles attached to bone to provide movement and are often arranged in antagonistic sets. Smooth muscle
5499-581: Is genetic mapping . In genetic mapping, visualizing synteny is one way to see the preserved order of genes on chromosomes. It is usually used for chromosomes of related species, both of which result from a common ancestor. This and other methods can shed light on evolutionary history. A recent study used comparative genomics to reconstruct 16 ancestral karyotypes across the mammalian phylogeny. The computational reconstruction showed how chromosomes rearranged themselves during mammal evolution. It gave insight into conservation of select regions often associated with
5640-507: Is a natural extension of pairwise inter-specific comparisons. Such comparisons typically aim to identify conserved regions across two phylogenetic scales: 1. Deep comparisons, often referred to as phylogenetic footprinting reveal conservation across higher taxonomic units like vertebrates. 2. Shallow comparisons, recently termed Phylogenetic shadowing , probe conservation across a group of closely related species. Whole-genome alignment (WGA) involves predicting evolutionary relationships at
5781-541: Is commonly taken to refer to human anatomy . However, substantially similar structures and tissues are found throughout the rest of the animal kingdom, and the term also includes the anatomy of other animals. The term zootomy is also sometimes used to specifically refer to non-human animals. The structure and tissues of plants are of a dissimilar nature and they are studied in plant anatomy . The kingdom Animalia contains multicellular organisms that are heterotrophic and motile (although some have secondarily adopted
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5922-473: Is found in the walls of the uterus , bladder , intestines , stomach , oesophagus , respiratory airways , and blood vessels . Cardiac muscle is found only in the heart , allowing it to contract and pump blood round the body. Nervous tissue is composed of many nerve cells known as neurons which transmit information. In some slow-moving radially symmetrical marine animals such as ctenophores and cnidarians (including sea anemones and jellyfish ),
6063-597: Is important for coding capacity and possibly for regulatory reasons. High gene density facilitates genome annotation , analysis of environmental selection. By contrast, low gene density hampers the mapping of genetic disease as in the human genome. Alignments are used to capture information about similar sequences such as ancestry, common evolutionary descent, or common structure and function. Alignments can be done for both nucleotide and protein sequences. Alignments consist of local or global pairwise alignments, and multiple sequence alignments. One way to find global alignments
6204-429: Is inherently tied to developmental biology , embryology , comparative anatomy , evolutionary biology , and phylogeny , as these are the processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology , which study the structure and function of organisms and their parts respectively, make a natural pair of related disciplines, and are often studied together. Human anatomy
6345-399: Is one of the essential basic sciences that are applied in medicine, and is often studied alongside physiology . Anatomy is a complex and dynamic field that is constantly evolving as discoveries are made. In recent years, there has been a significant increase in the use of advanced imaging techniques, such as MRI and CT scans , which allow for more detailed and accurate visualizations of
6486-423: Is one such method that utilizes whole genome alignment and it is designed to identify both structural and sequence differences between two whole-genome assemblies . By taking WGAs as input, SyRI initially scans for disparities in genome structures. Subsequently, it identifies local sequence variations within both rearranged and non-rearranged (syntenic) regions. Another computational method for comparative genomics
6627-467: Is phylogenetic reconstruction. It is used to describe evolutionary relationships in terms of common ancestors. The relationships are usually represented in a tree called a phylogenetic tree . Similarly, coalescent theory is a retrospective model to trace alleles of a gene in a population to a single ancestral copy shared by members of the population. This is also known as the most recent common ancestor . Analysis based on coalescence theory tries predicting
6768-483: Is quite distinct from physiology and biochemistry , which deal respectively with the functions of those parts and the chemical processes involved. For example, an anatomist is concerned with the shape, size, position, structure, blood supply and innervation of an organ such as the liver; while a physiologist is interested in the production of bile , the role of the liver in nutrition and the regulation of bodily functions. The discipline of anatomy can be subdivided into
6909-494: Is startlingly rapid". Between 1275 and 1326, the anatomists Mondino de Luzzi , Alessandro Achillini and Antonio Benivieni at Bologna carried out the first systematic human dissections since ancient times. Mondino's Anatomy of 1316 was the first textbook in the medieval rediscovery of human anatomy. It describes the body in the order followed in Mondino's dissections, starting with the abdomen, thorax, head, and limbs. It
7050-631: Is that these websites are being developed and updated constantly. There are many new settings and content can be used online to improve efficiency. Agriculture is a field that reaps the benefits of comparative genomics. Identifying the loci of advantageous genes is a key step in breeding crops that are optimized for greater yield , cost-efficiency, quality, and disease resistance . For example, one genome wide association study conducted on 517 rice landraces revealed 80 loci associated with several categories of agronomic performance, such as grain weight, amylose content, and drought tolerance . Many of
7191-399: Is the study of the interrelationships of all of the structures in a specific body region, such as the abdomen. In contrast, systemic anatomy is the study of the structures that make up a discrete body system—that is, a group of structures that work together to perform a unique body function, such as the digestive system. Anatomy can be studied using both invasive and non-invasive methods with
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#17327880244107332-411: Is the vertebral column, composed of articulating vertebrae which are lightweight yet strong. The ribs attach to the spine and there are no limbs or limb girdles. The main external features of the fish, the fins , are composed of either bony or soft spines called rays, which with the exception of the caudal fins , have no direct connection with the spine. They are supported by the muscles which compose
7473-495: Is to use a dynamic programming algorithm known as Needleman-Wunsch algorithm whereas Smith–Waterman algorithm used to find local alignments. With the exponential growth of sequence databases and the emergence of longer sequences, there's a heightened interest in faster, approximate, or heuristic alignment procedures. Among these, the FASTA and BLAST algorithms are prominent for local pairwise alignment. Recent years have witnessed
7614-567: Is very important to visualize the comparative results. Visualization of sequence conservation is a tough task of comparative sequence analysis. As we know, it is highly inefficient to examine the alignment of long genomic regions manually. Internet-based genome browsers provide many useful tools for investigating genomic sequences due to integrating all sequence-based biological information on genomic regions. When we extract large amount of relevant biological data, they can be very easy to use and less time-consuming. An advantage of using online tools
7755-609: The Hippocratic Corpus , an Ancient Greek medical work written by unknown authors. Aristotle described vertebrate anatomy based on animal dissection . Praxagoras identified the difference between arteries and veins . Also in the 4th century BCE, Herophilos and Erasistratus produced more accurate anatomical descriptions based on vivisection of criminals in Alexandria during the Ptolemaic period . In
7896-466: The DNA that is evolutionarily conserved between them. Therefore, Comparative genomics provides a powerful tool for studying evolutionary changes among organisms, helping to identify genes that are conserved or common among species, as well as genes that give unique characteristics of each organism. Moreover, these studies can be performed at different levels of the genomes to obtain multiple perspectives about
8037-511: The Triassic period. There is one living species, Sphenodon punctatus . The skull has two openings (fenestrae) on either side and the jaw is rigidly attached to the skull. There is one row of teeth in the lower jaw and this fits between the two rows in the upper jaw when the animal chews. The teeth are merely projections of bony material from the jaw and eventually wear down. The brain and heart are more primitive than those of other reptiles, and
8178-400: The epidermis and are found in localized bands from where they fan out over the skin. Large flight feathers are found on the wings and tail, contour feathers cover the bird's surface and fine down occurs on young birds and under the contour feathers of water birds. The only cutaneous gland is the single uropygial gland near the base of the tail. This produces an oily secretion that waterproofs
8319-533: The extracellular matrix . Often called fascia (from the Latin "fascia," meaning "band" or "bandage"), connective tissues give shape to organs and holds them in place. The main types are loose connective tissue, adipose tissue , fibrous connective tissue, cartilage and bone. The extracellular matrix contains proteins , the chief and most abundant of which is collagen . Collagen plays a major part in organizing and maintaining tissues. The matrix can be modified to form
8460-461: The mouthparts . The thorax has three pairs of segmented legs , one pair each for the three segments that compose the thorax and one or two pairs of wings . The abdomen is composed of eleven segments, some of which may be fused and houses the digestive , respiratory , excretory and reproductive systems. There is considerable variation between species and many adaptations to the body parts, especially wings, legs, antennae and mouthparts. Spiders
8601-400: The stomach . All vertebrates have a similar basic body plan and at some point in their lives, mostly in the embryonic stage, share the major chordate characteristics: a stiffening rod, the notochord ; a dorsal hollow tube of nervous material, the neural tube ; pharyngeal arches ; and a tail posterior to the anus. The spinal cord is protected by the vertebral column and is above
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#17327880244108742-420: The 2nd century, Galen of Pergamum , an anatomist, clinician , writer, and philosopher, wrote the final and highly influential anatomy treatise of ancient times. He compiled existing knowledge and studied anatomy through the dissection of animals. He was one of the first experimental physiologists through his vivisection experiments on animals. Galen's drawings, based mostly on dog anatomy, became effectively
8883-631: The Anatomy of the Muscles." Up until that point, Galen and his teachings had been the authority on human anatomy. The irony is that Galen himself had emphasized the fact that one should make one's own observations instead of using those of another, but this advice was lost during the numerous translations of his work. As Vesalius began to uncover these mistakes, other physicians of the time began to trust their own observations more than those of Galen. An interesting observation made by some of these physicians
9024-464: The Greek ἀνατομή anatomē "dissection" (from ἀνατέμνω anatémnō "I cut up, cut open" from ἀνά aná "up", and τέμνω témnō "I cut"), anatomy is the scientific study of the structure of organisms including their systems, organs and tissues . It includes the appearance and position of the various parts, the materials from which they are composed, and their relationships with other parts. Anatomy
9165-425: The ability to use information from one species to understand the same processes in another. We can get new insights into molecular pathways by comparing human and mouse T cells and their effects on the immune system utilizing comparative genomics. In order to comprehend its TCRs and their genes, Glusman conducted research on the sequencing of the human and mouse T cell receptor loci. TCR genes are well-known and serve as
9306-412: The amount of time between the introduction of a mutation and a particular allele or gene distribution in a population. This time period is equal to how long ago the most recent common ancestor existed. The inheritance relationships are visualized in a form similar to a phylogenetic tree. Coalescence (or the gene genealogy) can be visualized using dendrograms . An additional method in comparative genomics
9447-479: The and polypeptides.[Figure 1] However, several short noncoding conserved blocks of the genome had been shown. Both human and mouse motifs are largely clustered in the 200 bp [Figure 2], the known 3′ enhancers in the TCR/ were identified, and a conserved region of 100 bp in the mouse J intron was subsequently shown to have a regulatory function. Comparisons of the genomic sequences within each physical site or location of
9588-541: The arts and sciences from the Ptolemaic dynasty of Egypt helped raise Alexandria up, further rivalling other Greek states' cultural and scientific achievements. Some of the most striking advances in early anatomy and physiology took place in Hellenistic Alexandria. Two of the most famous anatomists and physiologists of the third century were Herophilus and Erasistratus . These two physicians helped pioneer human dissection for medical research, using
9729-496: The atria were parts of the heart. Herophilus's knowledge of the human body has provided vital input towards understanding the brain, eye, liver, reproductive organs, and nervous system and characterizing the course of the disease. Erasistratus accurately described the structure of the brain, including the cavities and membranes, and made a distinction between its cerebrum and cerebellum During his study in Alexandria, Erasistratus
9870-518: The basis of sense organs and there is a central nervous system (brain and spinal cord) and a peripheral nervous system . The latter consists of sensory nerves that transmit information from sense organs and motor nerves that influence target organs. The peripheral nervous system is divided into the somatic nervous system which conveys sensation and controls voluntary muscle , and the autonomic nervous system which involuntarily controls smooth muscle , certain glands and internal organs, including
10011-462: The body and they swim by undulating their body from side to side. Reptiles are a class of animals comprising turtles , tuataras , lizards , snakes and crocodiles . They are tetrapods , but the snakes and a few species of lizard either have no limbs or their limbs are much reduced in size. Their bones are better ossified and their skeletons stronger than those of amphibians. The teeth are conical and mostly uniform in size. The surface cells of
10152-427: The body's structures. The discipline of anatomy is divided into macroscopic and microscopic parts. Macroscopic anatomy , or gross anatomy, is the examination of an animal's body parts using unaided eyesight. Gross anatomy also includes the branch of superficial anatomy . Microscopic anatomy involves the use of optical instruments in the study of the tissues of various structures, known as histology , and also in
10293-399: The brain, appreciated the division between cerebellum and cerebrum and recognized that the brain was the "seat of intellect" and not a "cooling chamber" as propounded by Aristotle Herophilus is also credited with describing the optic, oculomotor, motor division of the trigeminal, facial, vestibulocochlear and hypoglossal nerves. Incredible feats were made during the third century BCE in both
10434-516: The cadavers of condemned criminals, which was considered taboo until the Renaissance—Herophilus was recognized as the first person to perform systematic dissections. Herophilus became known for his anatomical works, making impressive contributions to many branches of anatomy and many other aspects of medicine. Some of the works included classifying the system of the pulse, the discovery that human arteries had thicker walls than veins, and that
10575-413: The classification of animals. The first specifically anatomical investigation separate from a surgical or medical procedure is associated by . Leonardo da Vinci made notes for a planned anatomical treatise in which he intended to compare the hands of various animals including bears. Pierre Belon , a French naturalist born in 1517, conducted research and held discussions on dolphin embryos as well as
10716-610: The comparisons between the skeletons of birds to the skeletons of humans. His research led to modern comparative anatomy. Around the same time, Andreas Vesalius was also making some strides of his own. A young anatomist of Flemish descent made famous by a penchant for amazing charts, he was systematically investigating and correcting the anatomical knowledge of the Greek physician Galen. He noticed that many of Galen's observations were not even based on actual humans. Instead, they were based on other animals such as non-human apes , monkeys , and oxen . In fact, he entreated his students to do
10857-497: The conservation of homologous genes and gene order is identified between genomes of different species. Synteny blocks are more formally defined as regions of chromosomes between genomes that share a common order of homologous genes derived from a common ancestor. Alternative names such as conserved synteny or collinearity have been used interchangeably. Comparisons of genome synteny between and within species have provided an opportunity to study evolutionary processes that lead to
10998-438: The control of developmental processes. In addition, it helped to provide an understanding of chromosome evolution and genetic diseases associated with DNA rearrangements. Computational tools for analyzing sequences and complete genomes are developing quickly due to the availability of large amount of genomic data. At the same time, comparative analysis tools are progressed and improved. In the challenges about these analyses, it
11139-418: The dermis which are overlain by horny ones and are partially fused with the ribs and spine. The neck is long and flexible and the head and the legs can be drawn back inside the shell. Turtles are vegetarians and the typical reptile teeth have been replaced by sharp, horny plates. In aquatic species, the front legs are modified into flippers. Tuataras superficially resemble lizards but the lineages diverged in
11280-608: The development of programs tailored to aligning lengthy sequences, such as MUMmer (1999), BLASTZ (2003), and AVID (2003). While BLASTZ adopts a local approach, MUMmer and AVID are geared towards global alignment. To harness the benefits of both local and global alignment approaches, one effective strategy involves integrating them. Initially, a rapid variant of BLAST known as BLAT is employed to identify homologous "anchor" regions. These anchors are subsequently scrutinized to identify sets exhibiting conserved order and orientation. Such sets of anchors are then subjected to alignment using
11421-402: The digestive and reproductive systems. Herophilus discovered and described not only the salivary glands but also the small intestine and liver. He showed that the uterus is a hollow organ and described the ovaries and uterine tubes. He recognized that spermatozoa were produced by the testes and was the first to identify the prostate gland. The anatomy of the muscles and skeleton is described in
11562-653: The diversity of chromosome number and structure in many lineages across the tree of life; early discoveries using such approaches include chromosomal conserved regions in nematodes and yeast , evolutionary history and phenotypic traits of extremely conserved Hox gene clusters across animals and MADS-box gene family in plants, and karyotype evolution in mammals and plants. Furthermore, comparing two genomes not only reveals conserved domains or synteny but also aids in detecting copy number variations , single nucleotide polymorphisms (SNPs) , indels , and other genomic structural variations . Virtually started as soon as
11703-402: The egg-laying monotremes , the platypus and the echidnas of Australia. Most other mammals have a placenta through which the developing foetus obtains nourishment, but in marsupials , the foetal stage is very short and the immature young is born and finds its way to its mother's pouch where it latches on to a teat and completes its development. Humans have the overall body plan of
11844-532: The end of each male pedipalp is a spoon-shaped cymbium that acts to support the copulatory organ . In 1600 BCE, the Edwin Smith Papyrus , an Ancient Egyptian medical text , described the heart and its vessels, as well as the brain and its meninges and cerebrospinal fluid , and the liver , spleen , kidneys , uterus and bladder . It showed the blood vessels diverging from the heart. The Ebers Papyrus ( c. 1550 BCE ) features
11985-467: The epidermis are modified into horny scales which create a waterproof layer. Reptiles are unable to use their skin for respiration as do amphibians and have a more efficient respiratory system drawing air into their lungs by expanding their chest walls. The heart resembles that of the amphibian but there is a septum which more completely separates the oxygenated and deoxygenated bloodstreams. The reproductive system has evolved for internal fertilization, with
12126-413: The epidermis is normally formed of epithelial cells and secretes an extracellular matrix which provides support to the organism. An endoskeleton derived from the mesoderm is present in echinoderms , sponges and some cephalopods . Exoskeletons are derived from the epidermis and is composed of chitin in arthropods (insects, spiders, ticks, shrimps, crabs, lobsters). Calcium carbonate constitutes
12267-429: The epithelial lining and in the large intestine there are intestinal villi . Skin consists of an outer layer of keratinized stratified squamous epithelium that covers the exterior of the vertebrate body. Keratinocytes make up to 95% of the cells in the skin . The epithelial cells on the external surface of the body typically secrete an extracellular matrix in the form of a cuticle . In simple animals this may just be
12408-610: The equivalent of tissues and organs. Locomotion is often provided by cilia or flagella or may proceed via the advance of pseudopodia , food may be gathered by phagocytosis , energy needs may be supplied by photosynthesis and the cell may be supported by an endoskeleton or an exoskeleton . Some protozoans can form multicellular colonies. Metazoans are a multicellular organism, with different groups of cells serving different functions. The most basic types of metazoan tissues are epithelium and connective tissue, both of which are present in nearly all invertebrates. The outer surface of
12549-500: The evolutionary success of the organism will be unconserved (selection is neutral). One of the important goals of the field is the identification of the mechanisms of eukaryotic genome evolution. It is however often complicated by the multiplicity of events that have taken place throughout the history of individual lineages, leaving only distorted and superimposed traces in the genome of each living organism. For this reason comparative genomics studies of small model organisms (for example
12690-405: The father of microscopical anatomy, discovered that plants had tubules similar to those he saw in insects like the silk worm. He observed that when a ring-like portion of bark was removed on a trunk a swelling occurred in the tissues above the ring, and he unmistakably interpreted this as growth stimulated by food coming down from the leaves, and being captured above the ring. Arthropods comprise
12831-435: The feathers when the bird preens . There are scales on the legs, feet and claws on the tips of the toes. Mammals are a diverse class of animals, mostly terrestrial but some are aquatic and others have evolved flapping or gliding flight. They mostly have four limbs, but some aquatic mammals have no limbs or limbs modified into fins, and the forelimbs of bats are modified into wings. The legs of most mammals are situated below
12972-443: The features of ancient fish. They have a bony skeleton, are generally laterally flattened, have five pairs of gills protected by an operculum , and a mouth at or near the tip of the snout. The dermis is covered with overlapping scales . Bony fish have a swim bladder which helps them maintain a constant depth in the water column, but not a cloaca. They mostly spawn a large number of small eggs with little yolk which they broadcast into
13113-418: The first works of comparative anatomy. In the 18th and 19th century, great anatomists like George Cuvier , Richard Owen and Thomas Henry Huxley revolutionized our understanding of the basic build and systematics of vertebrates , laying the foundation for Charles Darwin 's work on evolution . An example of a 20th-century comparative anatomist is Victor Negus , who worked on the structure and evolution of
13254-527: The following, in substitution for human skeletons, as cited by Edward Tyson : "If you can't happen to see any of these, dissect an Ape, carefully view each Bone, &c. ..." Then he advises what sort of Apes to make choice of, as most resembling a Man : And conclude "One ought to know the Structure of all the Bones either in a Humane Body, or in an Apes ; 'tis best in both ; and then to go to
13395-686: The genome of a pathogen or a family of pathogens. Applying a comparative genomics approach by analyzing the genomes of several related pathogens can lead to the development of vaccines that are multi-protective. A team of researchers employed such an approach to create a universal vaccine for Group B Streptococcus , a group of bacteria responsible for severe neonatal infection . Comparative genomics can also be used to generate specificity for vaccines against pathogens that are closely related to commensal microorganisms. For example, researchers used comparative genomic analysis of commensal and pathogenic strains of E. coli to identify pathogen-specific genes as
13536-401: The genome sequence are compared, one can deduce the evolutionary relationships of the sequences in a phylogenetic tree. Based on a variety of biological genome data and the study of vertical and horizontal evolution processes, one can understand vital parts of the gene structure and its regulatory function. Similarity of related genomes is the basis of comparative genomics. If two creatures have
13677-460: The genomes and to study the biology of the individual genomes. Comparison of whole genome sequences provides a highly detailed view of how organisms are related to each other at the gene level. By comparing whole genome sequences, researchers gain insights into genetic relationships between organisms and study evolutionary changes . The major principle of comparative genomics is that common features of two organisms will often be encoded within
13818-447: The genomes of cancer cells and comparing them with healthy cells, researchers can uncover key genetic alterations driving tumorigenesis , tumor progression, and metastasis . This deep understanding of the genomic landscape of cancer has profound implications for precision oncology . Moreover, Comparative Genomics is instrumental in elucidating mechanisms of drug resistance —a major challenge in cancer treatment. T cells (also known as
13959-488: The goal of obtaining information about the structure and organization of organs and systems. Methods used include dissection , in which a body is opened and its organs studied, and endoscopy , in which a video camera -equipped instrument is inserted through a small incision in the body wall and used to explore the internal organs and other structures. Angiography using X-rays or magnetic resonance angiography are methods to visualize blood vessels. The term "anatomy"
14100-482: The head. The dermis is covered with separate dermal placoid scales . They have a cloaca into which the urinary and genital passages open, but not a swim bladder . Cartilaginous fish produce a small number of large, yolky eggs. Some species are ovoviviparous and the young develop internally but others are oviparous and the larvae develop externally in egg cases. The bony fish lineage shows more derived anatomical traits, often with major evolutionary changes from
14241-516: The human body were made, which contributed to the understanding of the brain, eye, liver, reproductive organs, and nervous system. The Hellenistic Egyptian city of Alexandria was the stepping-stone for Greek anatomy and physiology. Alexandria not only housed the biggest library for medical records and books of the liberal arts in the world during the time of the Greeks but was also home to many medical practitioners and philosophers. Great patronage of
14382-482: The identification of polymorphisms that are responsible for virulence, pathogenicity, and anti-biotic resistance. The system was also applied to the Minimal Organism Project at TIGR and subsequently to many other comparative genomics projects. Eukaryote genomes. Saccharomyces cerevisiae , the baker's yeast, was the first eukaryote to have its complete genome sequence published in 1996. After
14523-492: The immense size of the genome, comprising about three billion nucleotides. To tackle this challenge, comparative genomics offers a solution by pinpointing nucleotide positions that have remained unchanged over millions of years of evolution. These conserved regions indicate potential sites where genetic alterations could have detrimental effects on an organism's fitness, thus guiding the search for disease-causing variants. Moreover, comparative genomics holds promise in unraveling
14664-418: The impracticality caused by the size of the genomes. Next-generation sequencing methods, which were first introduced in 2007, have produced an enormous amount of genomic data and have allowed researchers to generate multiple (prokaryotic) draft genome sequences at once. These methods can also quickly uncover single-nucleotide polymorphisms , insertions and deletions by mapping unassembled reads against
14805-525: The large amount of data encoded in genomes. Many tools are now publicly available, ranging from whole genome comparisons to gene expression analysis. This includes approaches from systems and control, information theory, string analysis and data mining. Computational approaches will remain critical for research and teaching, especially when information science and genome biology is taught in conjunction. Comparative genomics starts with basic comparisons of genome size and gene density. For instance, genome size
14946-492: The largest phylum of invertebrates in the animal kingdom with over a million known species. Insects possess segmented bodies supported by a hard-jointed outer covering, the exoskeleton , made mostly of chitin . The segments of the body are organized into three distinct parts, a head, a thorax and an abdomen . The head typically bears a pair of sensory antennae , a pair of compound eyes , one to three simple eyes ( ocelli ) and three sets of modified appendages that form
15087-421: The larynx. Until the advent of genetic techniques like DNA sequencing , comparative anatomy together with embryology were the primary tools for understanding phylogeny , as exemplified by the work of Alfred Romer . Two major concepts of comparative anatomy are: Comparative anatomy has long served as evidence for evolution , now joined in that role by comparative genomics ; it indicates that organisms share
15228-434: The laws now named after him . Anatomy Anatomy (from Ancient Greek ἀνατομή ( anatomḗ ) ' dissection ') is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy
15369-399: The length of the sides of fish, and these respond to nearby movements and to changes in water pressure. Sharks and rays are basal fish with numerous primitive anatomical features similar to those of ancient fish, including skeletons composed of cartilage. Their bodies tend to be dorso-ventrally flattened, they usually have five pairs of gill slits and a large mouth set on the underside of
15510-534: The loci were previously uncharacterized. Not only is this methodology powerful, it is also quick. Previous methods of identifying loci associated with agronomic performance required several generations of carefully monitored breeding of parent strains, a time-consuming effort that is unnecessary for comparative genomic studies. The medical field also benefits from the study of comparative genomics. In an approach known as reverse vaccinology , researchers can discover candidate antigens for vaccine development by analyzing
15651-437: The lungs have a single chamber and lack bronchi . The tuatara has a well-developed parietal eye on its forehead. Lizards have skulls with only one fenestra on each side, the lower bar of bone below the second fenestra having been lost. This results in the jaws being less rigidly attached which allows the mouth to open wider. Lizards are mostly quadrupeds, with the trunk held off the ground by short, sideways-facing legs, but
15792-400: The main part of the trunk. The heart has two chambers and pumps the blood through the respiratory surfaces of the gills and on round the body in a single circulatory loop. The eyes are adapted for seeing underwater and have only local vision. There is an inner ear but no external or middle ear . Low frequency vibrations are detected by the lateral line system of sense organs that run along
15933-893: The mechanisms of gene evolution, environmental adaptations, gender-specific differences, and population variations across vertebrate lineages. Furthermore, comparative studies enable the identification of genomic signatures of selection—regions in the genome that have undergone preferential increase and fixation in populations due to their functional significance in specific processes. For instance, in animal genetics, indigenous cattle exhibit superior disease resistance and environmental adaptability but lower productivity compared to exotic breeds. Through comparative genomic analyses, significant genomic signatures responsible for these unique traits can be identified. Using insights from this signature, breeders can make informed decisions to enhance breeding strategies and promote breed development. Computational approaches are necessary for genome comparisons, given
16074-408: The model Caenorhabditis elegans and closely related Caenorhabditis briggsae ) are of great importance to advance our understanding of general mechanisms of evolution. Comparative genomics plays a crucial role in identifying copy number variations (CNVs) and understanding their significance in evolution. CNVs, which involve deletions or duplications of large segments of DNA, are recognized as
16215-477: The more developed animals whose structures and organs are formed from three germ layers are called triploblastic . All of a triploblastic animal's tissues and organs are derived from the three germ layers of the embryo, the ectoderm , mesoderm and endoderm . Animal tissues can be grouped into four basic types: connective , epithelial , muscle and nervous tissue . Connective tissues are fibrous and made up of cells scattered among inorganic material called
16356-475: The nerves form a nerve net , but in most animals they are organized longitudinally into bundles. In simple animals, receptor neurons in the body wall cause a local reaction to a stimulus. In more complex animals, specialized receptor cells such as chemoreceptors and photoreceptors are found in groups and send messages along neural networks to other parts of the organism. Neurons can be connected together in ganglia . In higher animals, specialized receptors are
16497-416: The notochord, and the gastrointestinal tract is below it. Nervous tissue is derived from the ectoderm , connective tissues are derived from mesoderm , and gut is derived from the endoderm . At the posterior end is a tail which continues the spinal cord and vertebrae but not the gut. The mouth is found at the anterior end of the animal, and the anus at the base of the tail. The defining characteristic of
16638-500: The nucleotide level between two or more genomes. It integrates elements of colinear sequence alignment and gene orthology prediction, presenting a greater challenge due to the vast size and intricate nature of whole genomes. Despite its complexity, numerous methods have emerged to tackle this problem because WGAs play a crucial role in various genome-wide analyses, such as phylogenetic inference, genome annotation, and function prediction. Thereby, SyRI (Synteny and Rearrangement Identifier)
16779-594: The number of sequenced genomes has grown. With the increasing reservoir of available genomic data, the potency of comparative genomic inference has grown as well. A notable case of this increased potency is found in recent primate research. Comparative genomic methods have allowed researchers to gather information about genetic variation , differential gene expression , and evolutionary dynamics in primates that were indiscernible using previous data and methods. The Great Ape Genome Project used comparative genomic methods to investigate genetic variation with reference to
16920-428: The only anatomical textbook for the next thousand years. His work was known to Renaissance doctors only through Islamic Golden Age medicine until it was translated from Greek sometime in the 15th century. Anatomy developed little from classical times until the sixteenth century; as the historian Marie Boas writes, "Progress in anatomy before the sixteenth century is as mysteriously slow as its development after 1500
17061-591: The organisms. The comparative genomic analysis begins with a simple comparison of the general features of genomes such as genome size, number of genes, and chromosome number. Table 1 presents data on several fully sequenced model organisms, and highlights some striking findings. For instance, while the tiny flowering plant Arabidopsis thaliana has a smaller genome than that of the fruit fly Drosophila melanogaster (157 million base pairs v. 165 million base pairs, respectively) it possesses nearly twice as many genes (25,000 v. 13,000). In fact, A. thaliana has approximately
17202-467: The publication of the roundworm Caenorhabditis elegans genome in 1998 and together with the fruit fly Drosophila melanogaster genome in 2000, Gerald M. Rubin and his team published a paper titled "Comparative Genomics of the Eukaryotes", in which they compared the genomes of the eukaryotes D. melanogaster , C. elegans , and S. cerevisiae , as well as the prokaryote H. influenzae . At
17343-599: The risk of adverse drug reactions, enhances treatment efficacy, and improves patient outcomes. Cancer Cancer Genomics represents a cutting-edge field within oncology that leverages comparative genomics to revolutionize cancer diagnosis, treatment, and prevention strategies. Comparative genomics plays a crucial role in cancer research by identifying driver mutations , and providing comprehensive analyses of mutations , copy number alterations, structural variants, gene expression , and DNA methylation profiles in large-scale studies across different cancer types. By analyzing
17484-416: The same number of genes as humans (25,000). Thus, a very early lesson learned in the genomic era is that genome size does not correlate with evolutionary status, nor is the number of genes proportionate to genome size. In comparative genomics, synteny is the preserved order of genes on chromosomes of related species indicating their descent from a common ancestor . Synteny provides a framework in which
17625-581: The same time, Bonnie Berger , Eric Lander , and their team published a paper on whole-genome comparison of human and mouse. With the publication of the large genomes of vertebrates in the 2000s, including human , the Japanese pufferfish Takifugu rubripes , and mouse , precomputed results of large genome comparisons have been released for downloading or for visualization in a genome browser . Instead of undertaking their own analyses, most biologists can access these large cross-species comparisons and avoid
17766-493: The same underlying skeletal structure was inherited from their last common ancestor. This is one of the arguments put forward by Charles Darwin to support his theory of evolution . The body of a fish is divided into a head, trunk and tail, although the divisions between the three are not always externally visible. The skeleton, which forms the support structure inside the fish, is either made of cartilage, in cartilaginous fish , or bone in bony fish . The main skeletal element
17907-670: The shells of molluscs , brachiopods and some tube-building polychaete worms and silica forms the exoskeleton of the microscopic diatoms and radiolaria . Other invertebrates may have no rigid structures but the epidermis may secrete a variety of surface coatings such as the pinacoderm of sponges, the gelatinous cuticle of cnidarians ( polyps , sea anemones , jellyfish ) and the collagenous cuticle of annelids . The outer epithelial layer may include cells of several types including sensory cells, gland cells and stinging cells. There may also be protrusions such as microvilli , cilia, bristles, spines and tubercles . Marcello Malpighi ,
18048-428: The study of cells . The history of anatomy is characterized by a progressive understanding of the functions of the organs and structures of the human body. Methods have also improved dramatically, advancing from the examination of animals by dissection of carcasses and cadavers (corpses) to 20th-century medical imaging techniques, including X-ray , ultrasound , and magnetic resonance imaging . Derived from
18189-741: The tail is laterally compressed. It undulates from side to side to force the animal through the water when swimming. The tough keratinized scales provide body armour and some are fused to the skull. The nostrils, eyes and ears are elevated above the top of the flat head enabling them to remain above the surface of the water when the animal is floating. Valves seal the nostrils and ears when it is submerged. Unlike other reptiles, crocodilians have hearts with four chambers allowing complete separation of oxygenated and deoxygenated blood. Birds are tetrapods but though their hind limbs are used for walking or hopping, their front limbs are wings covered with feathers and adapted for flight. Birds are endothermic , have
18330-401: The toes are often webbed for swimming or have suction pads for climbing. Frogs have large eyes and no tail. Salamanders resemble lizards in appearance; their short legs project sideways, the belly is close to or in contact with the ground and they have a long tail. Caecilians superficially resemble earthworms and are limbless. They burrow by means of zones of muscle contractions which move along
18471-538: The trunk, which is held well clear of the ground. The bones of mammals are well ossified and their teeth, which are usually differentiated, are coated in a layer of prismatic enamel . The teeth are shed once ( milk teeth ) during the animal's lifetime or not at all, as is the case in cetaceans . Mammals have three bones in the middle ear and a cochlea in the inner ear . They are clothed in hair and their skin contains glands which secrete sweat . Some of these glands are specialized as mammary glands , producing milk to feed
18612-442: The vertebrae. Their skulls are mostly broad and short, and are often incompletely ossified. Their skin contains little keratin and lacks scales, but contains many mucous glands and in some species, poison glands. The hearts of amphibians have three chambers, two atria and one ventricle . They have a urinary bladder and nitrogenous waste products are excreted primarily as urea . Amphibians breathe by means of buccal pumping ,
18753-437: The water column. Amphibians are a class of animals comprising frogs , salamanders and caecilians . They are tetrapods , but the caecilians and a few species of salamander have either no limbs or their limbs are much reduced in size. Their main bones are hollow and lightweight and are fully ossified and the vertebrae interlock with each other and have articular processes . Their ribs are usually short and may be fused to
18894-524: The whole genomes of two organisms became available (that is, the genomes of the bacteria Haemophilus influenzae and Mycoplasma genitalium ) in 1995, comparative genomics is now a standard component of the analysis of every new genome sequence. With the explosion in the number of genome projects due to the advancements in DNA sequencing technologies, particularly the next-generation sequencing methods in late 2000s, this field has become more sophisticated, making it possible to deal with many genomes in
19035-411: The young. Mammals breathe with lungs and have a muscular diaphragm separating the thorax from the abdomen which helps them draw air into the lungs. The mammalian heart has four chambers, and oxygenated and deoxygenated blood are kept entirely separate. Nitrogenous waste is excreted primarily as urea. Mammals are amniotes , and most are viviparous , giving birth to live young. Exceptions to this are
19176-425: Was also responsible for naming and describing the function of the epiglottis and the heart's valves, including the tricuspid. During the third century, Greek physicians were able to differentiate nerves from blood vessels and tendons and to realize that the nerves convey neural impulses. It was Herophilus who made the point that damage to motor nerves induced paralysis. Herophilus named the meninges and ventricles in
19317-622: Was developed in 1998 by Art Delcher, Simon Kasif and Steven Salzberg and applied to the comparison of entire highly related microbial organisms with their collaborators at the Institute for Genomic Research (TIGR). The system is called MUMMER and was described in a publication in Nucleic Acids Research in 1999. The system helps researchers to identify large rearrangements, single base mutations, reversals, tandem repeat expansions and other polymorphisms. In bacteria, MUMMER enables
19458-421: Was particularly concerned with studies of the circulatory and nervous systems. He could distinguish the human body's sensory and motor nerves and believed air entered the lungs and heart, which was then carried throughout the body. His distinction between the arteries and veins—the arteries carrying the air through the body, while the veins carry the blood from the heart was a great anatomical discovery. Erasistratus
19599-564: Was the presence of homologous structures in a wide variety of animals which included humans. These observations were later used by Darwin as he formed his theory of Natural Selection . Edward Tyson is regarded as the founder of modern comparative anatomy. He is credited with determining that whales and dolphins are, in fact, mammals. Also, he concluded that chimpanzees are more similar to humans than to monkeys because of their arms. Marco Aurelio Severino also compared various animals, including birds, in his Zootomia democritaea , one of
19740-426: Was the standard anatomy textbook for the next century. Comparative genomics Comparative genomics is a branch of biological research that examines genome sequences across a spectrum of species , spanning from humans and mice to a diverse array of organisms from bacteria to chimpanzees . This large-scale holistic approach compares two or more genomes to discover the similarities and differences between
19881-428: Was thought, would reflect two sorts of biological information: (1) exons and (2) regulatory sequences . In fact, the majority of V, D, J, and C exons could be identified in this method. The variable regions are encoded by multiple unique DNA elements that are rearranged and connected during T cell (TCR) differentiation: variable (V), diversity (D), and joining (J) elements for the and polypeptides; and V and J elements for
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