Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms . A sub-discipline of both chemistry and biology , biochemistry may be divided into three fields: structural biology , enzymology , and metabolism . Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells, in turn relating greatly to the understanding of tissues and organs as well as organism structure and function. Biochemistry is closely related to molecular biology , the study of the molecular mechanisms of biological phenomena.
93-1118: Nutrition is the biochemical and physiological process by which an organism uses food to support its life . It provides organisms with nutrients , which can be metabolized to create energy and chemical structures. Failure to obtain the required amount of nutrients causes malnutrition . Nutritional science is the study of nutrition, though it typically emphasizes human nutrition . The type of organism determines what nutrients it needs and how it obtains them. Organisms obtain nutrients by consuming organic matter , consuming inorganic matter, absorbing light, or some combination of these. Some can produce nutrients internally by consuming basic elements, while some must consume other organisms to obtain pre-existing nutrients. All forms of life require carbon , energy , and water as well as various other molecules . Animals require complex nutrients such as carbohydrates , lipids , and proteins , obtaining them by consuming other organisms. Humans have developed agriculture and cooking to replace foraging and advance human nutrition. Plants acquire nutrients through
186-628: A biological polymer , they undergo a process called dehydration synthesis . Different macromolecules can assemble in larger complexes, often needed for biological activity . Two of the main functions of carbohydrates are energy storage and providing structure. One of the common sugars known as glucose is a carbohydrate, but not all carbohydrates are sugars. There are more carbohydrates on Earth than any other known type of biomolecule; they are used to store energy and genetic information , as well as play important roles in cell to cell interactions and communications . The simplest type of carbohydrate
279-433: A carboxylic acid group, –COOH (although these exist as –NH 3 and –COO under physiologic conditions), a simple hydrogen atom , and a side chain commonly denoted as "–R". The side chain "R" is different for each amino acid of which there are 20 standard ones . It is this "R" group that makes each amino acid different, and the properties of the side chains greatly influence the overall three-dimensional conformation of
372-916: A flagellum to assist in hunting for food, and some protozoa travel via infectious spores to act as parasites. Many protists are mixotrophic, having both phototrophic and heterotrophic characteristics. Mixotrophic protists will typically depend on one source of nutrients while using the other as a supplemental source or a temporary alternative when its primary source is unavailable. Prokaryotes , including bacteria and archaea , vary greatly in how they obtain nutrients across nutritional groups. Prokaryotes can only transport soluble compounds across their cell envelopes, but they can break down chemical components around them. Some lithotrophic prokaryotes are extremophiles that can survive in nutrient-deprived environments by breaking down inorganic matter. Phototrophic prokaryotes, such as cyanobacteria and Chloroflexia , can engage in photosynthesis to obtain energy from sunlight. This
465-399: A chemical theory of metabolism, or even earlier to the 18th century studies on fermentation and respiration by Antoine Lavoisier . Many other pioneers in the field who helped to uncover the layers of complexity of biochemistry have been proclaimed founders of modern biochemistry. Emil Fischer , who studied the chemistry of proteins , and F. Gowland Hopkins , who studied enzymes and
558-434: A component of DNA . A monosaccharide can switch between acyclic (open-chain) form and a cyclic form. The open-chain form can be turned into a ring of carbon atoms bridged by an oxygen atom created from the carbonyl group of one end and the hydroxyl group of another. The cyclic molecule has a hemiacetal or hemiketal group, depending on whether the linear form was an aldose or a ketose . In these cyclic forms,
651-406: A cyclic [ring] and planar [flat] structure) while others are not. Some are flexible, while others are rigid. Lipids are usually made from one molecule of glycerol combined with other molecules. In triglycerides , the main group of bulk lipids, there is one molecule of glycerol and three fatty acids . Fatty acids are considered the monomer in that case, and maybe saturated (no double bonds in
744-468: A few (around three to six) monosaccharides are joined, it is called an oligosaccharide ( oligo- meaning "few"). These molecules tend to be used as markers and signals , as well as having some other uses. Many monosaccharides joined form a polysaccharide . They can be joined in one long linear chain, or they may be branched . Two of the most common polysaccharides are cellulose and glycogen , both consisting of repeating glucose monomers . Cellulose
837-763: A higher requirement of energy in comparison to plants. The macronutrients essential to animal life are carbohydrates, amino acids , and fatty acids . All macronutrients except water are required by the body for energy, however, this is not their sole physiological function. The energy provided by macronutrients in food is measured in kilocalories, usually called Calories, where 1 Calorie is the amount of energy required to raise 1 kilogram of water by 1 degree Celsius. Carbohydrates are molecules that store significant amounts of energy. Animals digest and metabolize carbohydrates to obtain this energy. Carbohydrates are typically synthesized by plants during metabolism, and animals have to obtain most carbohydrates from nature, as they have only
930-714: A limited ability to generate them. They include sugars , oligosaccharides , and polysaccharides . Glucose is the simplest form of carbohydrate. Carbohydrates are broken down to produce glucose and short-chain fatty acids , and they are the most abundant nutrients for herbivorous land animals. Carbohydrates contain 4 calories per gram. Lipids provide animals with fats and oils. They are not soluble in water, and they can store energy for an extended period of time. They can be obtained from many different plant and animal sources. Most dietary lipids are triglycerides , composed of glycerol and fatty acids. Phospholipids and sterols are found in smaller amounts. An animal's body will reduce
1023-404: A molecule with a 5-membered ring, called glucofuranose . The same reaction can take place between carbons 1 and 5 to form a molecule with a 6-membered ring, called glucopyranose . Cyclic forms with a 7-atom ring called heptoses are rare. Two monosaccharides can be joined by a glycosidic or ester bond into a disaccharide through a dehydration reaction during which a molecule of water
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#17327726543751116-566: A nutrient deficiency. Early human nutrition consisted of foraging for nutrients, like other animals, but it diverged at the beginning of the Holocene with the Neolithic Revolution , in which humans developed agriculture to produce food. The Chemical Revolution in the 18th century allowed humans to study the nutrients in foods and develop more advanced methods of food preparation . Major advances in economics and technology during
1209-414: A protein. Some amino acids have functions by themselves or in a modified form; for instance, glutamate functions as an important neurotransmitter . Amino acids can be joined via a peptide bond . In this dehydration synthesis, a water molecule is removed and the peptide bond connects the nitrogen of one amino acid's amino group to the carbon of the other's carboxylic acid group. The resulting molecule
1302-566: A reducing end because of full acetal formation between the aldehyde carbon of glucose (C1) and the keto carbon of fructose (C2). Lipids comprise a diverse range of molecules and to some extent is a catchall for relatively water-insoluble or nonpolar compounds of biological origin, including waxes , fatty acids , fatty-acid derived phospholipids , sphingolipids , glycolipids , and terpenoids (e.g., retinoids and steroids ). Some lipids are linear, open-chain aliphatic molecules, while others have ring structures. Some are aromatic (with
1395-481: A significant increase in human intake of fats and oils. Humans have developed advanced methods of food processing that prevent contamination of pathogenic microorganisms and simplify the production of food. These include drying, freezing, heating, milling, pressing, packaging, refrigeration, and irradiation. Most cultures add herbs and spices to foods before eating to add flavor, though most do not significantly affect nutrition. Other additives are also used to improve
1488-440: A study of the components and composition of living things and how they come together to become life. In this sense, the history of biochemistry may therefore go back as far as the ancient Greeks . However, biochemistry as a specific scientific discipline began sometime in the 19th century, or a little earlier, depending on which aspect of biochemistry is being focused on. Some argued that the beginning of biochemistry may have been
1581-566: A variety of foods. Cultivation of cereals and production of bread has made up a key component of human nutrition since the beginning of agriculture. Early humans hunted animals for meat, and modern humans domesticate animals to consume their meat and eggs. The development of animal husbandry has also allowed humans in some cultures to consume the milk of other animals and process it into foods such as cheese . Other foods eaten by humans include nuts, seeds, fruits, and vegetables. Access to domesticated animals as well as vegetable oils has caused
1674-431: Is a monosaccharide , which among other properties contains carbon , hydrogen , and oxygen , mostly in a ratio of 1:2:1 (generalized formula C n H 2 n O n , where n is at least 3). Glucose (C 6 H 12 O 6 ) is one of the most important carbohydrates; others include fructose (C 6 H 12 O 6 ), the sugar commonly associated with the sweet taste of fruits , and deoxyribose (C 5 H 10 O 4 ),
1767-412: Is an energy source in most life forms. For instance, polysaccharides are broken down into their monomers by enzymes ( glycogen phosphorylase removes glucose residues from glycogen, a polysaccharide). Disaccharides like lactose or sucrose are cleaved into their two component monosaccharides. Glucose is mainly metabolized by a very important ten-step pathway called glycolysis , the net result of which
1860-407: Is an important structural component of plant's cell walls and glycogen is used as a form of energy storage in animals. Sugar can be characterized by having reducing or non-reducing ends. A reducing end of a carbohydrate is a carbon atom that can be in equilibrium with the open-chain aldehyde ( aldose ) or keto form ( ketose ). If the joining of monomers takes place at such a carbon atom,
1953-424: Is called a dipeptide , and short stretches of amino acids (usually, fewer than thirty) are called peptides or polypeptides . Longer stretches merit the title proteins . As an example, the important blood serum protein albumin contains 585 amino acid residues . Proteins can have structural and/or functional roles. For instance, movements of the proteins actin and myosin ultimately are responsible for
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#17327726543752046-485: Is common among bacteria that form in mats atop geothermal springs. Phototrophic prokaryotes typically obtain carbon from assimilating carbon dioxide through the Calvin cycle . Some prokaryotes, such as Bdellovibrio and Ensifer , are predatory and feed on other single-celled organisms. Predatory prokaryotes seek out other organisms through chemotaxis or random collision, merge with the organism, degrade it, and absorb
2139-489: Is governed by nutrition. Migration patterns and seasonal breeding take place in conjunction with food availability, and courtship displays are used to display an animal's health. Animals develop positive and negative associations with foods that affect their health, and they can instinctively avoid foods that have caused toxic injury or nutritional imbalances through a conditioned food aversion . Some animals, such as rats, do not seek out new types of foods unless they have
2232-850: Is in contrast to phototrophs , which use photons. Chemotrophs can be either autotrophic or heterotrophic . Chemotrophs can be found in areas where electron donors are present in high concentration, for instance around hydrothermal vents . Chemoautotrophs are autotrophic organisms that can rely on chemosynthesis , i.e. deriving biological energy from chemical reactions of environmental inorganic substrates and synthesizing all necessary organic compounds from carbon dioxide . Chemoautotrophs can use inorganic energy sources such as hydrogen sulfide , elemental sulfur , ferrous iron , molecular hydrogen , and ammonia or organic sources to produce energy. Most chemoautotrophs are prokaryotic extremophiles , bacteria , or archaea that live in otherwise hostile environments (such as deep sea vents ) and are
2325-554: Is managed by humans through animal feed . Fodder and forage are provided to livestock. Specialized pet food has been manufactured since 1860, and subsequent research and development have addressed the nutritional needs of pets. Dog food and cat food in particular are heavily studied and typically include all essential nutrients for these animals. Cats are sensitive to some common nutrients, such as taurine , and require additional nutrients derived from meat. Large-breed puppies are susceptible to overnutrition, as small-breed dog food
2418-569: Is more energy dense than they can absorb. Most plants obtain nutrients through inorganic substances absorbed from the soil or the atmosphere. Carbon, hydrogen, oxygen, nitrogen, and sulfur are essential nutrients that make up organic material in a plant and allow enzymic processes. These are absorbed ions in the soil, such as bicarbonate , nitrate , ammonium , and sulfate , or they are absorbed as gases, such as carbon dioxide, water, oxygen gas, and sulfur dioxide . Phosphorus, boron, and silicon are used for esterification . They are obtained through
2511-493: Is needed to carry out the oxidation. Iron has many existing roles in biology not related to redox reactions; examples include iron–sulfur proteins , hemoglobin , and coordination complexes . Iron has a widespread distribution globally and is considered one of the most abundant in the Earth's crust, soil, and sediments. Iron is a trace element in marine environments . Its role as the electron donor for some chemolithotrophs
2604-421: Is not an essential element for plants. Plants need boron and silicon , but animals may not (or may need ultra-small amounts). Just six elements— carbon , hydrogen , nitrogen , oxygen , calcium and phosphorus —make up almost 99% of the mass of living cells, including those in the human body (see composition of the human body for a complete list). In addition to the six major elements that compose most of
2697-508: Is released. The reverse reaction in which the glycosidic bond of a disaccharide is broken into two monosaccharides is termed hydrolysis . The best-known disaccharide is sucrose or ordinary sugar , which consists of a glucose molecule and a fructose molecule joined. Another important disaccharide is lactose found in milk, consisting of a glucose molecule and a galactose molecule. Lactose may be hydrolysed by lactase , and deficiency in this enzyme results in lactose intolerance . When
2790-506: Is the generic name of the family of biopolymers . They are complex, high-molecular-weight biochemical macromolecules that can convey genetic information in all living cells and viruses. The monomers are called nucleotides , and each consists of three components: a nitrogenous heterocyclic base (either a purine or a pyrimidine ), a pentose sugar, and a phosphate group. The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The phosphate group and
2883-492: Is thought to be the reason why complex life appeared only after Earth's atmosphere accumulated large amounts of oxygen. In vertebrates , vigorously contracting skeletal muscles (during weightlifting or sprinting, for example) do not receive enough oxygen to meet the energy demand, and so they shift to anaerobic metabolism , converting glucose to lactate. The combination of glucose from noncarbohydrates origin, such as fat and proteins. This only happens when glycogen supplies in
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2976-409: Is to break down one molecule of glucose into two molecules of pyruvate . This also produces a net two molecules of ATP , the energy currency of cells, along with two reducing equivalents of converting NAD (nicotinamide adenine dinucleotide: oxidized form) to NADH (nicotinamide adenine dinucleotide: reduced form). This does not require oxygen; if no oxygen is available (or the cell cannot use oxygen),
3069-640: The Great Depression and the Second World War. Due to its importance in human health, the study of nutrition has heavily emphasized human nutrition and agriculture, while ecology is a secondary concern. Nutrients are substances that provide energy and physical components to the organism, allowing it to survive, grow, and reproduce. Nutrients can be basic elements or complex macromolecules . Approximately 30 elements are found in organic matter , with nitrogen , carbon , and phosphorus being
3162-438: The carbon cycle , sulfur cycle , nitrogen cycle , water cycle , phosphorus cycle , and oxygen cycle , among others that continually recycle along with other mineral nutrients into productive ecological nutrition. Biogeochemical cycles that are performed by living organisms and natural processes are water , carbon , nitrogen , phosphorus , and sulfur cycles . Nutrient cycles allow these essential elements to return to
3255-567: The chemistry required for biological activity of molecules, molecular biology studies their biological activity, genetics studies their heredity, which happens to be carried by their genome . This is shown in the following schematic that depicts one possible view of the relationships between the fields: Chemotroph A chemotroph is an organism that obtains energy by the oxidation of electron donors in their environments. These molecules can be organic ( chemoorganotrophs ) or inorganic ( chemolithotrophs ). The chemotroph designation
3348-399: The diet of an organism is the sum of the foods it eats. A healthy diet improves the physical and mental health of an organism. This requires ingestion and absorption of vitamins , minerals , essential amino acids from protein and essential fatty acids from fat-containing food. Carbohydrates , protein and fat play major roles in ensuring the quality of life , health and longevity of
3441-416: The essential amino acids . Mammals do possess the enzymes to synthesize alanine , asparagine , aspartate , cysteine , glutamate , glutamine , glycine , proline , serine , and tyrosine , the nonessential amino acids. While they can synthesize arginine and histidine , they cannot produce it in sufficient amounts for young, growing animals, and so these are often considered essential amino acids. If
3534-424: The glutamate residue at position 6 with a valine residue changes the behavior of hemoglobin so much that it results in sickle-cell disease . Finally, quaternary structure is concerned with the structure of a protein with multiple peptide subunits, like hemoglobin with its four subunits. Not all proteins have more than one subunit. Ingested proteins are usually broken up into single amino acids or dipeptides in
3627-479: The primary producers in such ecosystems . Chemoautotrophs generally fall into several groups: methanogens , sulfur oxidizers and reducers , nitrifiers , anammox bacteria, and thermoacidophiles . An example of one of these prokaryotes would be Sulfolobus . Chemolithotrophic growth can be dramatically fast, such as Hydrogenovibrio crunogenus with a doubling time around one hour. The term "chemosynthesis", coined in 1897 by Wilhelm Pfeffer , originally
3720-549: The small intestine and then absorbed. They can then be joined to form new proteins. Intermediate products of glycolysis, the citric acid cycle, and the pentose phosphate pathway can be used to form all twenty amino acids, and most bacteria and plants possess all the necessary enzymes to synthesize them. Humans and other mammals, however, can synthesize only half of them. They cannot synthesize isoleucine , leucine , lysine , methionine , phenylalanine , threonine , tryptophan , and valine . Because they must be ingested, these are
3813-401: The soil and the atmosphere. Fungi absorb nutrients around them by breaking them down and absorbing them through the mycelium . Scientific analysis of food and nutrients began during the chemical revolution in the late 18th century. Chemists in the 18th and 19th centuries experimented with different elements and food sources to develop theories of nutrition. Modern nutrition science began in
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3906-399: The " vital principle ") distinct from any found in non-living matter, and it was thought that only living beings could produce the molecules of life. In 1828, Friedrich Wöhler published a paper on his serendipitous urea synthesis from potassium cyanate and ammonium sulfate ; some regarded that as a direct overthrow of vitalism and the establishment of organic chemistry . However,
3999-403: The 1910s as individual micronutrients began to be identified. The first vitamin to be chemically identified was thiamine in 1926, and vitamin C was identified as a protection against scurvy in 1932. The role of vitamins in nutrition was studied in the following decades. The first recommended dietary allowances for humans were developed to address fears of disease caused by food deficiencies during
4092-417: The 20th century allowed mass production and food fortification to better meet the nutritional needs of humans. Human behavior is closely related to human nutrition, making it a subject of social science in addition to biology. Nutrition in humans is balanced with eating for pleasure, and optimal diet may vary depending on the demographics and health concerns of each person. Humans are omnivores that eat
4185-518: The N-terminal domain. The enzyme-linked immunosorbent assay (ELISA), which uses antibodies, is one of the most sensitive tests modern medicine uses to detect various biomolecules. Probably the most important proteins, however, are the enzymes . Virtually every reaction in a living cell requires an enzyme to lower the activation energy of the reaction. These molecules recognize specific reactant molecules called substrates ; they then catalyze
4278-492: The NAD is restored by converting the pyruvate to lactate (lactic acid) (e.g. in humans) or to ethanol plus carbon dioxide (e.g. in yeast ). Other monosaccharides like galactose and fructose can be converted into intermediates of the glycolytic pathway. In aerobic cells with sufficient oxygen , as in most human cells, the pyruvate is further metabolized. It is irreversibly converted to acetyl-CoA , giving off one carbon atom as
4371-485: The Wöhler synthesis has sparked controversy as some reject the death of vitalism at his hands. Since then, biochemistry has advanced, especially since the mid-20th century, with the development of new techniques such as chromatography , X-ray diffraction , dual polarisation interferometry , NMR spectroscopy , radioisotopic labeling , electron microscopy and molecular dynamics simulations. These techniques allowed for
4464-416: The amino group is removed from an amino acid, it leaves behind a carbon skeleton called an α- keto acid . Enzymes called transaminases can easily transfer the amino group from one amino acid (making it an α-keto acid) to another α-keto acid (making it an amino acid). This is important in the biosynthesis of amino acids, as for many of the pathways, intermediates from other biochemical pathways are converted to
4557-434: The amount of energy gained from glycolysis (six molecules of ATP are used, compared to the two gained in glycolysis). Analogous to the above reactions, the glucose produced can then undergo glycolysis in tissues that need energy, be stored as glycogen (or starch in plants), or be converted to other monosaccharides or joined into di- or oligosaccharides. The combined pathways of glycolysis during exercise, lactate's crossing via
4650-582: The amount of fatty acids it produces as dietary fat intake increases, while it increases the amount of fatty acids it produces as carbohydrate intake increases. Fats contain 9 calories per gram. Protein consumed by animals is broken down to amino acids, which would be later used to synthesize new proteins. Protein is used to form cellular structures, fluids, and enzymes (biological catalysts ). Enzymes are essential to most metabolic processes, as well as DNA replication , repair , and transcription . Protein contains 4 calories per gram. Much of animal behavior
4743-837: The amount of protein in a food. Humans can also obtain energy from ethanol , which is both a food and a drug, but it provides relatively few essential nutrients and is associated with nutritional deficiencies and other health risks. In humans, poor nutrition can cause deficiency-related diseases, such as blindness , anemia , scurvy , preterm birth , stillbirth and cretinism , or nutrient-excess conditions, such as obesity and metabolic syndrome . Other conditions possibly affected by nutrition disorders include cardiovascular diseases , diabetes , and osteoporosis . Undernutrition can lead to wasting in acute cases, and stunting of marasmus in chronic cases of malnutrition. In domesticated animals , such as pets , livestock , and working animals , as well as other animals in captivity , nutrition
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#17327726543754836-475: The amount of time and energy spent foraging. It was created to analyze the foraging habits of animals, but it can also be extended to other organisms. Some organisms are specialists that are adapted to forage for a single food source, while others are generalists that can consume a variety of food sources. Nutrient deficiencies, known as malnutrition , occur when an organism does not have the nutrients that it needs. This may be caused by suddenly losing nutrients or
4929-878: The animals' needs. Unicellular organisms release the ammonia into the environment. Likewise, bony fish can release ammonia into the water where it is quickly diluted. In general, mammals convert ammonia into urea, via the urea cycle . In order to determine whether two proteins are related, or in other words to decide whether they are homologous or not, scientists use sequence-comparison methods. Methods like sequence alignments and structural alignments are powerful tools that help scientists identify homologies between related molecules. The relevance of finding homologies among proteins goes beyond forming an evolutionary pattern of protein families . By finding how similar two protein sequences are, we acquire knowledge about their structure and therefore their function. Nucleic acids , so-called because of their prevalence in cellular nuclei ,
5022-468: The bloodstream to the liver, subsequent gluconeogenesis and release of glucose into the bloodstream is called the Cori cycle . Researchers in biochemistry use specific techniques native to biochemistry, but increasingly combine these with techniques and ideas developed in the fields of genetics , molecular biology , and biophysics . There is not a defined line between these disciplines. Biochemistry studies
5115-513: The body and are broken into fatty acids and glycerol, the final degradation products of fats and lipids. Lipids, especially phospholipids , are also used in various pharmaceutical products , either as co-solubilizers (e.g. in parenteral infusions) or else as drug carrier components (e.g. in a liposome or transfersome ). Proteins are very large molecules—macro-biopolymers—made from monomers called amino acids . An amino acid consists of an alpha carbon atom attached to an amino group, –NH 2 ,
5208-539: The carbon chain) or unsaturated (one or more double bonds in the carbon chain). Most lipids have some polar character and are largely nonpolar. In general, the bulk of their structure is nonpolar or hydrophobic ("water-fearing"), meaning that it does not interact well with polar solvents like water . Another part of their structure is polar or hydrophilic ("water-loving") and will tend to associate with polar solvents like water. This makes them amphiphilic molecules (having both hydrophobic and hydrophilic portions). In
5301-743: The carbon of other organisms, while autotrophs are organisms that produce their own nutrients from the carbon of inorganic substances like carbon dioxide . Mixotrophs are organisms that can be heterotrophs and autotrophs, including some plankton and carnivorous plants . Phototrophs obtain energy from light, while chemotrophs obtain energy by consuming chemical energy from matter. Organotrophs consume other organisms to obtain electrons, while lithotrophs obtain electrons from inorganic substances, such as water , hydrogen sulfide , dihydrogen , iron(II) , sulfur , or ammonium . Prototrophs can create essential nutrients from other compounds, while auxotrophs must consume preexisting nutrients. In nutrition,
5394-490: The case of cholesterol , the polar group is a mere –OH (hydroxyl or alcohol). In the case of phospholipids, the polar groups are considerably larger and more polar, as described below. Lipids are an integral part of our daily diet. Most oils and milk products that we use for cooking and eating like butter , cheese , ghee etc. are composed of fats . Vegetable oils are rich in various polyunsaturated fatty acids (PUFA). Lipid-containing foods undergo digestion within
5487-651: The causes and cures of diseases . Nutrition studies how to maintain health and wellness and also the effects of nutritional deficiencies . In agriculture, biochemists investigate soil and fertilizers with the goal of improving crop cultivation, crop storage, and pest control . In recent decades, biochemical principles and methods have been combined with problem-solving approaches from engineering to manipulate living systems in order to produce useful tools for research, industrial processes, and diagnosis and control of disease—the discipline of biotechnology . At its most comprehensive definition, biochemistry can be seen as
5580-507: The contraction of skeletal muscle. One property many proteins have is that they specifically bind to a certain molecule or class of molecules—they may be extremely selective in what they bind. Antibodies are an example of proteins that attach to one specific type of molecule. Antibodies are composed of heavy and light chains. Two heavy chains would be linked to two light chains through disulfide linkages between their amino acids. Antibodies are specific through variation based on differences in
5673-591: The discovery and detailed analysis of many molecules and metabolic pathways of the cell , such as glycolysis and the Krebs cycle (citric acid cycle), and led to an understanding of biochemistry on a molecular level. Another significant historic event in biochemistry is the discovery of the gene , and its role in the transfer of information in the cell. In the 1950s, James D. Watson , Francis Crick , Rosalind Franklin and Maurice Wilkins were instrumental in solving DNA structure and suggesting its relationship with
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#17327726543755766-492: The discovery of the first enzyme , diastase (now called amylase ), in 1833 by Anselme Payen , while others considered Eduard Buchner 's first demonstration of a complex biochemical process alcoholic fermentation in cell-free extracts in 1897 to be the birth of biochemistry. Some might also point as its beginning to the influential 1842 work by Justus von Liebig , Animal chemistry, or, Organic chemistry in its applications to physiology and pathology , which presented
5859-519: The dynamic nature of biochemistry, represent two examples of early biochemists. The term "biochemistry" was first used when Vinzenz Kletzinsky (1826–1882) had his "Compendium der Biochemie" printed in Vienna in 1858; it derived from a combination of biology and chemistry . In 1877, Felix Hoppe-Seyler used the term ( biochemie in German) as a synonym for physiological chemistry in the foreword to
5952-554: The electrons from high-energy states in NADH and quinol is conserved first as proton gradient and converted to ATP via ATP synthase. This generates an additional 28 molecules of ATP (24 from the 8 NADH + 4 from the 2 quinols), totaling to 32 molecules of ATP conserved per degraded glucose (two from glycolysis + two from the citrate cycle). It is clear that using oxygen to completely oxidize glucose provides an organism with far more energy than any oxygen-independent metabolic feature, and this
6045-490: The environment after being absorbed or consumed. Without proper nutrient cycling, there would be risk of change in oxygen levels, climate, and ecosystem function. Foraging is the process of seeking out nutrients in the environment. It may also be defined to include the subsequent use of the resources. Some organisms, such as animals and bacteria, can navigate to find nutrients, while others, such as plants and fungi, extend outward to find nutrients. Foraging may be random, in which
6138-426: The enzyme can be regulated, enabling control of the biochemistry of the cell as a whole. The structure of proteins is traditionally described in a hierarchy of four levels. The primary structure of a protein consists of its linear sequence of amino acids; for instance, "alanine-glycine-tryptophan-serine-glutamate-asparagine-glycine-lysine-...". Secondary structure is concerned with local morphology (morphology being
6231-469: The enzyme complexes of the respiratory chain, an electron transport system transferring the electrons ultimately to oxygen and conserving the released energy in the form of a proton gradient over a membrane ( inner mitochondrial membrane in eukaryotes). Thus, oxygen is reduced to water and the original electron acceptors NAD and quinone are regenerated. This is why humans breathe in oxygen and breathe out carbon dioxide. The energy released from transferring
6324-448: The first issue of Zeitschrift für Physiologische Chemie (Journal of Physiological Chemistry) where he argued for the setting up of institutes dedicated to this field of study. The German chemist Carl Neuberg however is often cited to have coined the word in 1903, while some credited it to Franz Hofmeister . It was once generally believed that life and its materials had some essential property or substance (often referred to as
6417-467: The free hydroxy group of the pyranose or furanose form is exchanged with an OH-side-chain of another sugar, yielding a full acetal . This prevents opening of the chain to the aldehyde or keto form and renders the modified residue non-reducing. Lactose contains a reducing end at its glucose moiety, whereas the galactose moiety forms a full acetal with the C4-OH group of glucose. Saccharose does not have
6510-531: The genetic material of the cell, nucleic acids often play a role as second messengers , as well as forming the base molecule for adenosine triphosphate (ATP), the primary energy-carrier molecule found in all living organisms. Also, the nitrogenous bases possible in the two nucleic acids are different: adenine, cytosine, and guanine occur in both RNA and DNA, while thymine occurs only in DNA and uracil occurs in RNA. Glucose
6603-526: The genetic transfer of information. In 1958, George Beadle and Edward Tatum received the Nobel Prize for work in fungi showing that one gene produces one enzyme . In 1988, Colin Pitchfork was the first person convicted of murder with DNA evidence, which led to the growth of forensic science . More recently, Andrew Z. Fire and Craig C. Mello received the 2006 Nobel Prize for discovering
6696-448: The human body, humans require smaller amounts of possibly 18 more. The 4 main classes of molecules in biochemistry (often called biomolecules ) are carbohydrates , lipids , proteins , and nucleic acids . Many biological molecules are polymers : in this terminology, monomers are relatively small macromolecules that are linked together to create large macromolecules known as polymers. When monomers are linked together to synthesize
6789-741: The inability to absorb proper nutrients. Not only is malnutrition the result of a lack of necessary nutrients, but it can also be a result of other illnesses and health conditions. When this occurs, an organism will adapt by reducing energy consumption and expenditure to prolong the use of stored nutrients. It will use stored energy reserves until they are depleted, and it will then break down its own body mass for additional energy. A balanced diet includes appropriate amounts of all essential and non-essential nutrients. These can vary by age, weight, sex, physical activity levels, and more. A lack of just one essential nutrient can cause bodily harm, just as an overabundance can cause toxicity. The Daily Reference Values keep
6882-458: The liver are worn out. The pathway is a crucial reversal of glycolysis from pyruvate to glucose and can use many sources like amino acids, glycerol and Krebs Cycle . Large scale protein and fat catabolism usually occur when those suffer from starvation or certain endocrine disorders. The liver regenerates the glucose, using a process called gluconeogenesis . This process is not quite the opposite of glycolysis, and actually requires three times
6975-852: The majority of people from nutrient deficiencies. DRVs are not recommendations but a combination of nutrient references to educate professionals and policymakers on what the maximum and minimum nutrient intakes are for the average person. Food labels also use DRVs as a reference to create safe nutritional guidelines for the average healthy person. Animals are heterotrophs that consume other organisms to obtain nutrients. Herbivores are animals that eat plants, carnivores are animals that eat other animals, and omnivores are animals that eat both plants and other animals. Many herbivores rely on bacterial fermentation to create digestible nutrients from indigestible plant cellulose, while obligate carnivores must eat animal meats to obtain certain vitamins or nutrients their bodies cannot otherwise synthesize. Animals generally have
7068-821: The most important. Macronutrients are the primary substances required by an organism, and micronutrients are substances required by an organism in trace amounts. Organic micronutrients are classified as vitamins , and inorganic micronutrients are classified as minerals . Nutrients are absorbed by the cells and used in metabolic biochemical reactions. These include fueling reactions that create precursor metabolites and energy, biosynthetic reactions that convert precursor metabolites into building block molecules, polymerizations that combine these molecules into macromolecule polymers , and assembly reactions that use these polymers to construct cellular structures. Organisms can be classified by how they obtain carbon and energy. Heterotrophs are organisms that obtain nutrients by consuming
7161-431: The organism seeks nutrients without method, or it may be systematic, in which the organism can go directly to a food source. Organisms are able to detect nutrients through taste or other forms of nutrient sensing , allowing them to regulate nutrient intake. Optimal foraging theory is a model that explains foraging behavior as a cost–benefit analysis in which an animal must maximize the gain of nutrients while minimizing
7254-422: The organism. Some cultures and religions have restrictions on what is acceptable for their diet. A nutrient cycle is a biogeochemical cycle involving the movement of inorganic matter through a combination of soil, organisms, air or water, where they are exchanged in organic matter. Energy flow is a unidirectional and noncyclic pathway, whereas the movement of mineral nutrients is cyclic. Mineral cycles include
7347-410: The reaction between them. By lowering the activation energy , the enzyme speeds up that reaction by a rate of 10 or more; a reaction that would normally take over 3,000 years to complete spontaneously might take less than a second with an enzyme. The enzyme itself is not used up in the process and is free to catalyze the same reaction with a new set of substrates. Using various modifiers, the activity of
7440-553: The released nutrients. Predatory strategies of prokaryotes include attaching to the outer surface of the organism and degrading it externally, entering the cytoplasm of the organism, or by entering the periplasmic space of the organism. Groups of predatory prokaryotes may forgo attachment by collectively producing hydrolytic enzymes. Biochemistry Much of biochemistry deals with the structures, functions, and interactions of biological macromolecules such as proteins , nucleic acids , carbohydrates , and lipids . They provide
7533-413: The ring usually has 5 or 6 atoms. These forms are called furanoses and pyranoses , respectively—by analogy with furan and pyran , the simplest compounds with the same carbon-oxygen ring (although they lack the carbon-carbon double bonds of these two molecules). For example, the aldohexose glucose may form a hemiacetal linkage between the hydroxyl on carbon 1 and the oxygen on carbon 4, yielding
7626-559: The role of RNA interference (RNAi) in the silencing of gene expression . Around two dozen chemical elements are essential to various kinds of biological life . Most rare elements on Earth are not needed by life (exceptions being selenium and iodine ), while a few common ones ( aluminum and titanium ) are not used. Most organisms share element needs, but there are a few differences between plants and animals . For example, ocean algae use bromine , but land plants and animals do not seem to need any. All animals require sodium , but
7719-896: The root-like mycelium, which grows through the organism's source of nutrients and can extend indefinitely. The fungus excretes extracellular enzymes to break down surrounding matter and then absorbs the nutrients through the cell wall. Fungi can be parasitic, saprophytic, or symbiotic. Parasitic fungi attach and feed on living hosts, such as animals, plants, or other fungi. Saprophytic fungi feed on dead and decomposing organisms. Symbiotic fungi grow around other organisms and exchange nutrients with them. Protists include all eukaryotes that are not animals, plants, or fungi, resulting in great diversity between them. Algae are photosynthetic protists that can produce energy from light. Several types of protists use mycelium similar to those of fungi. Protozoa are heterotrophic protists, and different protozoa seek nutrients in different ways. Flagellate protozoa use
7812-430: The safety, quality, flavor, and nutritional content of food. Humans obtain most carbohydrates as starch from cereals, though sugar has grown in importance. Lipids can be found in animal fat , butterfat , vegetable oil, and leaf vegetables , and they are also used to increase flavor in foods. Protein can be found in virtually all foods, as it makes up cellular material, though certain methods of food processing may reduce
7905-472: The soil as phosphates , boric acid , and silicic acid , respectively. Other nutrients used by plants are potassium, sodium, calcium, magnesium, manganese, chlorine, iron, copper, zinc, and molybdenum. Plants uptake essential elements from the soil through their roots and from the air (consisting of mainly nitrogen and oxygen) through their leaves . Nutrient uptake in the soil is achieved by cation exchange , wherein root hairs pump hydrogen ions (H) into
7998-526: The soil in which they grow. This is made possible by the fact that largely inert atmospheric nitrogen is changed in a nitrogen fixation process to biologically usable forms in the soil by bacteria. As these nutrients do not provide the plant with energy, they must obtain energy by other means. Green plants absorb energy from sunlight with chloroplasts and convert it to usable energy through photosynthesis . Fungi are chemoheterotrophs that consume external matter for energy. Most fungi absorb matter through
8091-418: The soil through proton pumps . These hydrogen ions displace cations attached to negatively charged soil particles so that the cations are available for uptake by the root. In the leaves, stomata open to take in carbon dioxide and expel oxygen . Although nitrogen is plentiful in the Earth's atmosphere, very few plants can use this directly. Most plants, therefore, require nitrogen compounds to be present in
8184-585: The structure of cells and perform many of the functions associated with life. The chemistry of the cell also depends upon the reactions of small molecules and ions . These can be inorganic (for example, water and metal ions) or organic (for example, the amino acids , which are used to synthesize proteins ). The mechanisms used by cells to harness energy from their environment via chemical reactions are known as metabolism . The findings of biochemistry are applied primarily in medicine , nutrition and agriculture . In medicine, biochemists investigate
8277-476: The study of structure). Some combinations of amino acids will tend to curl up in a coil called an α-helix or into a sheet called a β-sheet ; some α-helixes can be seen in the hemoglobin schematic above. Tertiary structure is the entire three-dimensional shape of the protein. This shape is determined by the sequence of amino acids. In fact, a single change can change the entire structure. The alpha chain of hemoglobin contains 146 amino acid residues; substitution of
8370-683: The sugar of each nucleotide bond with each other to form the backbone of the nucleic acid, while the sequence of nitrogenous bases stores the information. The most common nitrogenous bases are adenine , cytosine , guanine , thymine , and uracil . The nitrogenous bases of each strand of a nucleic acid will form hydrogen bonds with certain other nitrogenous bases in a complementary strand of nucleic acid. Adenine binds with thymine and uracil, thymine binds only with adenine, and cytosine and guanine can bind only with one another. Adenine, thymine, and uracil contain two hydrogen bonds, while hydrogen bonds formed between cytosine and guanine are three. Aside from
8463-425: The waste product carbon dioxide , generating another reducing equivalent as NADH . The two molecules acetyl-CoA (from one molecule of glucose) then enter the citric acid cycle , producing two molecules of ATP, six more NADH molecules and two reduced (ubi)quinones (via FADH 2 as enzyme-bound cofactor), and releasing the remaining carbon atoms as carbon dioxide. The produced NADH and quinol molecules then feed into
8556-474: The α-keto acid skeleton, and then an amino group is added, often via transamination . The amino acids may then be linked together to form a protein. A similar process is used to break down proteins. It is first hydrolyzed into its component amino acids. Free ammonia (NH3), existing as the ammonium ion (NH4+) in blood, is toxic to life forms. A suitable method for excreting it must therefore exist. Different tactics have evolved in different animals, depending on
8649-997: Was defined as the energy production by oxidation of inorganic substances in association with autotrophy — what would be named today as chemolithoautotrophy . Later, the term would include also the chemoorganoautotrophy , that is, it can be seen as a synonym of chemoautotrophy. Chemoheterotrophs (or chemotrophic heterotrophs) are unable to fix carbon to form their own organic compounds. Chemoheterotrophs can be chemolithoheterotrophs , utilizing inorganic electron sources such as sulfur, or, much more commonly, chemoorganoheterotrophs , utilizing organic electron sources such as carbohydrates , lipids , and proteins . Most animals and fungi are examples of chemoheterotrophs, as are halophiles . Iron-oxidizing bacteria are chemotrophic bacteria that derive energy by oxidizing dissolved ferrous iron . They are known to grow and proliferate in waters containing iron concentrations as low as 0.1 mg/L. However, at least 0.3 ppm of dissolved oxygen
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