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90-520: It can be found in red wine, in barley , in beer , in peach or in Jatropha macrantha , the Huanarpo Macho. It has been identified as a hair-growth stimulant . Molar equivalents of synthetic (2R,3S,4R or S)- leucocyanidin and (+)- catechin condense with exceptional rapidity at pH 5 under ambient conditions to give the all-trans-[4,8]- and [4,6]-bi-[(+)-catechins] (procyanidins B3, B6 )

180-474: A sheaf ") and his son Beow ("Barley") are associated with the grain, or are possibly corn-gods; J. R. R. Tolkien wrote a poem "King Sheave" about them, and based a major element of his legendarium , the Old Straight Road from Middle-earth to the earthly paradise of Valinor , on their story. William of Malmesbury 's 12th century Chronicle tells the story of the related figure Sceafa as

270-470: A brittle spike ; upon maturity, the spikelets separate, facilitating seed dispersal . Domesticated barley has nonshattering spikelets, making it much easier to harvest the mature ears. The nonshattering condition is caused by a mutation in one of two tightly linked genes known as Bt 1 and Bt 2 ; many cultivars possess both mutations. The nonshattering condition is recessive , so varieties of barley that exhibit this condition are homozygous for

360-528: A circular structure, but some evidence suggests that chloroplast DNA more commonly takes a linear shape. Over 95% of the chloroplast DNA in corn chloroplasts has been observed to be in branched linear form rather than individual circles. Many chloroplast DNAs contain two inverted repeats , which separate a long single copy section (LSC) from a short single copy section (SSC). The inverted repeats vary wildly in length, ranging from 4,000 to 25,000 base pairs long each. Inverted repeats in plants tend to be at

450-504: A contour length of around 30–60 micrometers, and have a mass of about 80–130 million daltons . Most chloroplasts have their entire chloroplast genome combined into a single large ring, though those of dinophyte algae are a notable exception—their genome is broken up into about forty small plasmids , each 2,000–10,000 base pairs long. Each minicircle contains one to three genes, but blank plasmids, with no coding DNA , have also been found. Chloroplast DNA has long been thought to have

540-477: A cytosolic guidance complex that makes it easier for the chloroplast polypeptide to get imported into the chloroplast. Alternatively, if a chloroplast preprotein's transit peptide is not phosphorylated, a chloroplast preprotein can still attach to a heat shock protein or Toc159 . These complexes can bind to the TOC complex on the outer chloroplast membrane using GTP energy. The TOC complex , or t ranslocon on

630-485: A different protein kinase than the one that phosphorylates Toc34. Its M-domain forms part of the tunnel that chloroplast preproteins travel through, and seems to provide the force that pushes preproteins through, using the energy from GTP . Toc159 is not always found as part of the TOC complex—it has also been found dissolved in the cytosol . This suggests that it might act as a shuttle that finds chloroplast preproteins in

720-440: A disk 13 nanometers across. The whole core complex weighs about 500 kilodaltons . The other two proteins, Toc64 and Toc12, are associated with the core complex but are not part of it. Toc34 is an integral protein in the outer chloroplast membrane that's anchored into it by its hydrophobic C-terminal tail. Most of the protein, however, including its large guanosine triphosphate (GTP)-binding domain projects out into

810-627: A double displacement loop (D-loop). As the D-loop moves through the circular DNA, it adopts a theta intermediary form, also known as a Cairns replication intermediate, and completes replication with a rolling circle mechanism. Replication starts at specific points of origin. Multiple replication forks open up, allowing replication machinery to replicate the DNA. As replication continues, the forks grow and eventually converge. The new cpDNA structures separate, creating daughter cpDNA chromosomes. In addition to

900-433: A few tRNA genes still work in the mitochondrion . Some transferred chloroplast DNA protein products get directed to the secretory pathway (though many secondary plastids are bounded by an outermost membrane derived from the host's cell membrane , and therefore topologically outside of the cell, because to reach the chloroplast from the cytosol , you have to cross the cell membrane , just like if you were headed for

990-416: A loss of RNA editing resulting in a loss of function for photosynthesis genes. The mechanism for chloroplast DNA (cpDNA) replication has not been conclusively determined, but two main models have been proposed. Scientists have attempted to observe chloroplast replication via electron microscopy since the 1970s. The results of the microscopy experiments led to the idea that chloroplast DNA replicates using

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1080-435: A meal). Consuming breakfast cereals containing barley over weeks to months improves cholesterol levels and glucose regulation. Barley contains gluten , which makes it an unsuitable grain for consumption by people with gluten-related disorders , such as coeliac disease , non-coeliac gluten sensitivity and wheat allergy sufferers. Nevertheless, some wheat allergy patients can tolerate barley. Barley, made into malt ,

1170-403: A mix), and there are important differences in enzyme content, kernel shape, and other factors that malters and brewers must take into consideration. In traditional taxonomy, different forms of barley were classified as different species based on morphological differences. Two-row barley with shattering spikes (wild barley) was named Hordeum spontaneum . Two-row barley with nonshattering spikes

1260-606: A simple inheritance-based tree. Bambusoideae (bamboos)  ( fescue , ryegrass ) Hordeum (barley) Triticum (wheat) Secale (rye) Oryza (rice) other grasses Sorghum (sorghum) Zea (maize) Barley was one of the first grains to be domesticated in the Fertile Crescent , an area of relatively abundant water in Western Asia, around 9,000 BC. Wild barley ( H. vulgare ssp. spontaneum ) ranges from North Africa and Crete in

1350-525: A sleeping child in a boat without oars with a sheaf of corn at his head. Axel Olrik identified Peko , a parallel "barley-figure" in Finnish culture, in turn connected by R.D. Fulk with the Eddaic Bergelmir . In English folklore , the figure of John Barleycorn in the folksong of the same name is a personification of barley, and of the alcoholic beverages made from it: beer and whisky. In

1440-571: A total of 5000 Mbp. Details of the genome are freely available in several barley databases. The barley genus Hordeum is relatively closely related to wheat and rye within the Triticeae , and more distantly to rice within the BOP clade of grasses ( Poaceae ). The phylogeny of the Triticeae is complicated by hybridization between species, so there is a network of relationships rather than

1530-401: Is a form of domesticated barley with an easier-to-remove hull . Naked barley is an ancient food crop, but a new industry has developed around uses of selected hulless barley to increase the digestibility of the grain, especially for pigs and poultry. Hulless barley has been investigated for several potential new applications as whole grain, bran, and flour. In 2022, world production of barley

1620-523: Is a key ingredient in beer and whisky production. Two-row barley is traditionally used in German and English beers. Six-row barley was traditionally used in US beers , but both varieties are in common usage now. Distilled from green beer, Scottish and Irish whisky are made primarily from barley. About 25% of American barley is used for malting, for which barley is the best-suited grain. Accordingly, barley

1710-479: Is a lot worse at this than Toc34 or Toc159. Arabidopsis thaliana has multiple isoforms of Toc75 that are named by the chromosomal positions of the genes that code for them. AtToc75 III is the most abundant of these. The TIC translocon , or t ranslocon on the i nner c hloroplast membrane translocon is another protein complex that imports proteins across the inner chloroplast envelope . Chloroplast polypeptide chains probably often travel through

1800-508: Is a traditional Jewish stew often eaten on the Sabbath , in numerous recipes by both Mizrachi and Ashkenazi Jews ; its original form was a barley porridge. In Eastern and Central Europe, barley is used in soups and stews such as ričet . In Africa, where it is a traditional food plant, it has the potential to improve nutrition, boost food security, foster rural development, and support sustainable landcare. The six-row variety bere

1890-548: Is an integral protein thought to have four transmembrane α-helices . It is found in the 1 million dalton TIC complex. Because it is similar to bacterial amino acid transporters and the mitochondrial import protein Tim17 ( t ranslocase on the i nner m itochondrial m embrane ), it has been proposed to be part of the TIC import channel. There is no in vitro evidence for this though. In Arabidopsis thaliana , it

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1980-636: Is at best mixed. Barley grains were once used for measurement in England, there being nominally three or four barleycorns to the inch. By the 19th century, this had been superseded by standard inch measures. In ancient Mesopotamia , barley was used as a form of money, the standard unit of weight for barley, and hence of value, being the shekel . In the Old English poem Beowulf , and in Norse mythology , Scyld Scefing (the second name meaning "with

2070-599: Is cultivated in Orkney , Shetland, Caithness and the Western Isles of the Scottish Highlands and Islands . When milled into beremeal , it is used locally in bread , biscuits , and the traditional beremeal bannock . In Japanese cuisine, barley is mixed with rice and steamed as mugimeshi . The naval surgeon Takaki Kanehiro introduced it into institutional cooking to combat beriberi , endemic in

2160-653: Is grown around the world in temperate areas. It grows best in well-drained soil in full sunshine. In the tropics and subtropics, it is grown for food and straw in South Asia, North and East Africa, and in the Andes of South America. In dry regions it requires irrigation. It has a short growing season and is relatively drought-tolerant . Barley is more tolerant of soil salinity than other cereals, varying in different cultivars. It has less winter-hardiness than winter wheat and far less than rye. Like other cereals, barley

2250-430: Is heavily reduced compared to that of free-living cyanobacteria. Chloroplasts may contain 60–100 genes whereas cyanobacteria often have more than 1500 genes in their genome. The parasitic Pilostyles have even lost their plastid genes for tRNA . Contrarily, there are only a few known instances where genes have been transferred to the chloroplast from various donors, including bacteria. Endosymbiotic gene transfer

2340-418: Is how we know about the lost chloroplasts in many chromalveolate lineages. Even if a chloroplast is eventually lost, the genes it donated to the former host's nucleus persist, providing evidence for the lost chloroplast's existence. For example, while diatoms (a heterokontophyte ) now have a red algal derived chloroplast , the presence of many green algal genes in the diatom nucleus provide evidence that

2430-401: Is mostly under nuclear control, though chloroplasts can also give out signals regulating gene expression in the nucleus, called retrograde signaling . Protein synthesis within chloroplasts relies on an RNA polymerase coded by the chloroplast's own genome, which is related to RNA polymerases found in bacteria. Chloroplasts also contain a mysterious second RNA polymerase that is encoded by

2520-486: Is not associated with true histones , in red algae , a histone-like chloroplast protein (HC) coded by the chloroplast DNA that tightly packs each chloroplast DNA ring into a nucleoid has been found. In primitive red algae , the chloroplast DNA nucleoids are clustered in the center of a chloroplast, while in green plants and green algae , the nucleoids are dispersed throughout the stroma . More than 5000 chloroplast genomes have been sequenced and are accessible via

2610-565: Is often cleaved off, leaving an 86 kilodalton fragment called Toc86 . In the middle is its GTP binding domain, which is very similar to the homologous GTP-binding domain in Toc34. At the C-terminal end is the hydrophilic M-domain, which anchors the protein to the outer chloroplast membrane. Toc159 probably works a lot like Toc34, recognizing proteins in the cytosol using GTP . It can be regulated through phosphorylation , but by

2700-578: Is often assessed by its malting enzyme content. Barley wine is a style of strong beer from the English brewing tradition. An 18th-century alcoholic drink of the same name was made by boiling barley in water, then mixing the barley water with white wine, borage , lemon and sugar. In the 19th century, a different barley wine was prepared from recipes of ancient Greek origin. Nonalcoholic drinks such as barley water and roasted barley tea have been made by boiling barley in water. In Italy, roasted barley

2790-414: Is single stranded. When replication forks form, the strand not being copied is single stranded, and thus at risk for A → G deamination. Therefore, gradients in deamination indicate that replication forks were most likely present and the direction that they initially opened (the highest gradient is most likely nearest the start site because it was single stranded for the longest amount of time). This mechanism

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2880-535: Is sometimes used as coffee substitute, caffè d'orzo (barley coffee). Some 70% of the world's barley production is used as livestock feed, for example for cattle feeding in western Canada. In 2014, an enzymatic process was devised to make a high-protein fish feed from barley, suitable for carnivorous fish such as trout and salmon . Barley straw has been placed in mesh bags and floated in fish ponds or water gardens to help prevent algal growth without harming pond plants and animals. The technique's effectiveness

2970-675: Is still the leading theory today; however, a second theory suggests that most cpDNA is actually linear and replicates through homologous recombination. It further contends that only a minority of the genetic material is kept in circular chromosomes while the rest is in branched, linear, or other complex structures. One of the main competing models for cpDNA asserts that most cpDNA is linear and participates in homologous recombination and replication structures similar to bacteriophage T4 . It has been established that some plants have linear cpDNA, such as maize, and that more still contain complex structures that scientists do not yet understand; however,

3060-630: Is susceptible to several viral diseases, such as barley mild mosaic bymovirus . Some viruses, such as barley yellow dwarf virus , vectored by the rice root aphid , can cause serious crop injury. For durable disease resistance, quantitative resistance is more important than qualitative resistance . The most important foliar diseases have corresponding resistance gene regions on all chromosomes of barley. A large number of molecular markers are available for breeding of resistance to leaf rust, powdery mildew, Rhynchosporium secalis , Pyrenophora teres f. teres , Barley yellow dwarf virus , and

3150-454: Is the DNA located in chloroplasts, which are photosynthetic organelles located within the cells of some eukaryotic organisms. Chloroplasts, like other types of plastid , contain a genome separate from that in the cell nucleus . The existence of chloroplast DNA was identified biochemically in 1959, and confirmed by electron microscopy in 1962. The discoveries that the chloroplast contains ribosomes and performs protein synthesis revealed that

3240-466: Is the most abundant protein on the outer chloroplast envelope. It is a transmembrane tube that forms most of the TOC pore itself. Toc75 is a β-barrel channel lined by 16 β-pleated sheets . The hole it forms is about 2.5 nanometers wide at the ends, and shrinks to about 1.4–1.6 nanometers in diameter at its narrowest point—wide enough to allow partially folded chloroplast preproteins to pass through. Toc75 can also bind to chloroplast preproteins, but

3330-589: Is the most common in Arabidopsis , and it is the functional analogue of Toc34 because it can be turned off by phosphorylation. AtToc34 on the other hand cannot be phosphorylated. Toc159 is another GTP binding TOC subunit , like Toc34 . Toc159 has three domains . At the N-terminal end is the A-domain, which is rich in acidic amino acids and takes up about half the protein length. The A-domain

3420-425: Is typically planted on tilled land. Seed was traditionally scattered , but in developed countries is usually drilled . As it grows it requires soil nutrients (nitrogen, phosphorus, potassium), often supplied as fertilizers. It needs to be monitored for pests and diseases, and if necessary treated before these become serious. The stems and ears turn yellow when ripe, and the ears begin to droop. Traditional harvesting

3510-403: Is used as animal feed , while 30% is used as a source of fermentable material for beer , or further distilled into whisky , and as a component of various foods. It is used in soups and stews and in barley bread of various cultures. Barley grains are commonly made into malt using a traditional and ancient method of preparation. In English folklore, John Barleycorn personifies the grain and

3600-631: Is used in gruel . This gruel is known as سويق : sawīq in the Arab world . With a long history of cultivation in the Middle East , barley is used in a wide range of traditional Arabic , Assyrian , Israelite , Kurdish , and Persian foodstuffs including keşkek , kashk , and murri . Barley soup is traditionally eaten during Ramadan in Saudi Arabia. Cholent or hamin (in Hebrew)

3690-453: The Barley yellow mosaic virus complex . Hulled barley (or covered barley) is eaten after removing the inedible, fibrous, outer husk or hull. Once removed, it is called dehulled barley (or pot barley or scotch barley). Pearl barley (or pearled barley) is dehulled to remove most of the bran, and polished. Barley meal, a wholemeal barley flour lighter than wheat meal but darker in colour,

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3780-508: The Fertile Crescent around 9000 BC, giving it nonshattering spikelets and making it much easier to harvest . Its use then spread throughout Eurasia by 2000 BC. Barley prefers relatively low temperatures and well-drained soil to grow. It is relatively tolerant of drought and soil salinity but is less winter-hardy than wheat or rye . In 2022, barley was fourth among grains in quantity produced, 155 million tonnes , behind maize , wheat, and rice . Globally, 70% of barley production

3870-422: The extracellular space . In those cases, chloroplast-targeted proteins do initially travel along the secretory pathway). Because the cell acquiring a chloroplast already had mitochondria (and peroxisomes , and a cell membrane for secretion), the new chloroplast host had to develop a unique protein targeting system to avoid having chloroplast proteins being sent to the wrong organelle . Polypeptides ,

3960-490: The genus is from Latin hordeum , barley, likely related to Latin horrere , to bristle. Barley is a cereal , a member of the grass family with edible grains. Its flowers are clusters of spikelets arranged in a distinctive herringbone pattern . Each spikelet has a long thin awn (to 160 mm (6.3 in) long), making the ears look tufted. The spikelets are in clusters of three. In six-row barley, all three spikelets in each cluster are fertile; in two-row barley, only

4050-401: The inner chloroplast membrane . After a chloroplast polypeptide is synthesized on a ribosome in the cytosol , ATP energy can be used to phosphorylate , or add a phosphate group to many (but not all) of them in their transit sequences. Serine and threonine (both very common in chloroplast transit sequences—making up 20–30% of the sequence) are often the amino acids that accept

4140-448: The o uter c hloroplast membrane , is a collection of proteins that imports preproteins across the outer chloroplast envelope . Five subunits of the TOC complex have been identified—two GTP -binding proteins Toc34 and Toc159 , the protein import tunnel Toc75 , plus the proteins Toc64 and Toc12 . The first three proteins form a core complex that consists of one Toc159, four to five Toc34s, and four Toc75s that form four holes in

4230-490: The phosphate group . The enzyme that carries out the phosphorylation is specific for chloroplast polypeptides, and ignores ones meant for mitochondria or peroxisomes . Phosphorylation changes the polypeptide's shape, making it easier for 14-3-3 proteins to attach to the polypeptide. In plants, 14-3-3 proteins only bind to chloroplast preproteins. It is also bound by the h eat s hock p rotein Hsp70 that keeps

4320-660: The rachis . In wild barley (and other Old World species of Hordeum ), only the central spikelet is fertile, while the other two are reduced. This condition is retained in certain cultivars known as two-row barleys. A pair of mutations (one dominant, the other recessive) result in fertile lateral spikelets to produce six-row barleys. A mutation in one gene, vrs1 , is responsible for the transition from two-row to six-row barley. Brewers in Europe tend to use two-row cultivars and breweries in North America use six-row barley (or

4410-721: The "front" end of a polypeptide— ribosomes synthesize polypeptides from the N-terminus to the C-terminus. Chloroplast transit peptides exhibit huge variation in length and amino acid sequence . They can be from 20 to 150 amino acids long —an unusually long length, suggesting that transit peptides are actually collections of domains with different functions. Transit peptides tend to be positively charged , rich in hydroxylated amino acids such as serine , threonine , and proline , and poor in acidic amino acids like aspartic acid and glutamic acid . In an aqueous solution ,

4500-516: The B vitamin niacin (14% DV), and dietary minerals , including iron (10% DV) and manganese (12% DV) (table). According to Health Canada and the US Food and Drug Administration , consuming at least 3 grams per day of barley beta-glucan can lower levels of blood cholesterol , a risk factor for cardiovascular diseases . Eating whole-grain barley, a high-fibre grain, improves regulation of blood sugar (i.e., reduces blood glucose response to

4590-704: The Korean Peninsula since the Early Mumun Pottery Period ( circa 1500–850 BC). Barley ( Yava in Sanskrit ) is mentioned many times in the Rigveda and other Indian scriptures as a principal grain in ancient India. Traces of barley cultivation have been found in post-Neolithic Bronze Age Harappan civilization 5,700–3,300 years ago. Barley beer was probably one of the first alcoholic drinks developed by Neolithic humans; later it

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4680-483: The NCBI organelle genome database. The first chloroplast genomes were sequenced in 1986, from tobacco ( Nicotiana tabacum ) and liverwort ( Marchantia polymorpha ). Comparison of the gene sequences of the cyanobacteria Synechocystis to those of the chloroplast genome of Arabidopsis provided confirmation of the endosymbiotic origin of the chloroplast. It also demonstrated the significant extent of gene transfer from

4770-512: The Toc34 protein release the chloroplast preprotein, handing it off to the next TOC protein. Toc34 then releases the depleted GDP molecule, probably with the help of an unknown GDP exchange factor . A domain of Toc159 might be the exchange factor that carry out the GDP removal. The Toc34 protein can then take up another molecule of GTP and begin the cycle again. Toc34 can be turned off through phosphorylation . A protein kinase drifting around on

4860-476: The alcoholic beverages made from it. English pub names such as The Barley Mow allude to its role in the production of beer. The Old English word for barley was bere . This survives in the north of Scotland as bere ; it is used for a strain of six-row barley grown there. Modern English barley derives from the Old English adjective bærlic , meaning "of barley". The word barn derives from Old English bere-aern meaning "barley-store". The name of

4950-464: The all-trans-[4,8:4,8]- and [4,8:4,6]-tri-[(+)-catechins] ( procyanidin C2 and isomer). This article about an aromatic compound is a stub . You can help Misplaced Pages by expanding it . Barley Barley ( Hordeum vulgare ), a member of the grass family , is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains ; it was domesticated in

5040-583: The armed forces in the 19th century. It became standard prison fare, and remains a staple in the Japan Self-Defense Forces . Cooked barley is 69% water, 28% carbohydrates , 2% protein , and 0.4% fat (table). In a 100-gram (3.5 oz) reference serving, cooked barley provides 515 kilojoules (123 kcal) of food energy and is a good source (10% or more of the Daily Value , DV) of essential nutrients , including, dietary fibre ,

5130-434: The barley, honey". The antiquary Cuthbert Sharp records that Elsie Marley was "a handsome, buxom, bustling landlady, and brought good custom to the [ale] house by her civility and attention." English pub names such as The Barley Mow, John Barleycorn, Malt Shovel, and Mash Tun allude to barley's role in the production of beer. Chloroplast DNA Chloroplast DNA ( cpDNA ), also known as plastid DNA ( ptDNA )

5220-629: The central one is fertile. It is a self-pollinating , diploid species with 14 chromosomes . The genome of barley was sequenced in 2012 by the International Barley Genome Sequencing Consortium and the UK Barley Sequencing Consortium. The genome is organised into seven pairs of nuclear chromosomes (recommended designations: 1H, 2H, 3H, 4H, 5H, 6H and 7H), and one mitochondrial and one chloroplast chromosome , with

5310-413: The chloroplast DNA to the nuclear genome in land plants. Of the approximately three-thousand proteins found in chloroplasts, some 95% of them are encoded by nuclear genes. Many of the chloroplast's protein complexes consist of subunits from both the chloroplast genome and the host's nuclear genome. As a result, protein synthesis must be coordinated between the chloroplast and the nucleus. The chloroplast

5400-441: The chloroplast is genetically semi-autonomous. The first complete chloroplast genome sequences were published in 1986, Nicotiana tabacum (tobacco) by Sugiura and colleagues and Marchantia polymorpha (liverwort) by Ozeki et al. Since then, tens of thousands of chloroplast genomes from various species have been sequenced . Chloroplast DNAs are circular, and are typically 120,000–170,000 base pairs long. They can have

5490-448: The chloroplast, and imported through at least two chloroplast membranes. Curiously, around half of the protein products of transferred genes aren't even targeted back to the chloroplast. Many became exaptations , taking on new functions like participating in cell division , protein routing , and even disease resistance . A few chloroplast genes found new homes in the mitochondrial genome —most became nonfunctional pseudogenes , though

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5580-473: The cyanobacterial ancestor to the nuclear genome. In most plant species, the chloroplast genome encodes approximately 120 genes. The genes primarily encode core components of the photosynthetic machinery and factors involved in their expression and assembly. Across species of land plants, the set of genes encoded by the chloroplast genome is fairly conserved. This includes four ribosomal RNAs , approximately 30 tRNAs , 21 ribosomal proteins , and 4 subunits of

5670-576: The cytosol and carries them back to the TOC complex. There isn't a lot of direct evidence for this behavior though. A family of Toc159 proteins, Toc159 , Toc132 , Toc120 , and Toc90 have been found in Arabidopsis thaliana . They vary in the length of their A-domains, which is completely gone in Toc90. Toc132, Toc120, and Toc90 seem to have specialized functions in importing stuff like nonphotosynthetic preproteins, and can't replace Toc159. Toc75

5760-414: The diatom ancestor (probably the ancestor of all chromalveolates too) had a green algal derived chloroplast at some point, which was subsequently replaced by the red chloroplast. In land plants, some 11–14% of the DNA in their nuclei can be traced back to the chloroplast, up to 18% in Arabidopsis , corresponding to about 4,500 protein-coding genes. There have been a few recent transfers of genes from

5850-595: The domestication of barley, in the form of cultivars that cannot reproduce without human assistance, comes from Mesopotamia, specifically the Jarmo region of modern-day Iraq, around 9,000–7,000 BC. Domestication changed the morphology of the barley grain substantially, from an elongated shape to a more rounded spherical one. Wild barley has distinctive genes , alleles , and regulators with potential for resistance to abiotic or biotic stresses ; these may help cultivated barley to adapt to climatic changes. Wild barley has

5940-561: The early microscopy experiments, this model is also supported by the amounts of deamination seen in cpDNA. Deamination occurs when an amino group is lost and is a mutation that often results in base changes. When adenine is deaminated, it becomes hypoxanthine (H). Hypoxanthine can bind to cytosine , and when the HC base pair is replicated, it becomes a GC (thus, an A → G base change). In cpDNA, there are several A → G deamination gradients. DNA becomes susceptible to deamination events when it

6030-631: The editing site. The distance between the binding site and editing site varies by gene and proteins involved in the editosome. Hundreds of different PPR proteins from the nuclear genome are involved in the RNA editing process. These proteins consist of 35-mer repeated amino acids, the sequence of which determines the cis binding site for the edited transcript. Basal land plants such as liverworts, mosses and ferns have hundreds of different editing sites while flowering plants typically have between thirty and forty. Parasitic plants such as Epifagus virginiana show

6120-470: The fifth century AD. This grain, along with a cool climate that permitted storage, produced a civilization that was able to raise great armies. It is made into a flour product called tsampa that is still a staple in Tibet. In medieval Europe, bread made from barley and rye was peasant food, while wheat products were consumed by the upper classes. Spikelets are arranged in triplets which alternate along

6210-424: The genomes of cyanobacteria and the other two chloroplast lineages ( glaucophyta and rhodophyceæ ), suggesting that they predate the chloroplast, though some chloroplast DNAs like those of peas and a few red algae have since lost the inverted repeats. Others, like the red alga Porphyra flipped one of its inverted repeats (making them direct repeats). It is possible that the inverted repeats help stabilize

6300-582: The initiates, prepared from barley and herbs, mentioned in the Homeric hymn to Demeter . The goddess's name may have meant "barley-mother", incorporating the ancient Cretan word δηαί (dēai), "barley". The practice was to dry the barley groats and roast them before preparing the porridge, according to Pliny the Elder 's Natural History . Tibetan barley has been a staple food in Tibetan cuisine since

6390-667: The mutant allele . Domestication in barley is followed by the change of key phenotypic traits at the genetic level. The wild barley found currently in the Fertile Crescent may not be the progenitor of the barley cultivated in Eritrea and Ethiopia , indicating that it may have been domesticated separately in eastern Africa. Archaeobotanical evidence shows that barley had spread throughout Eurasia by 2,000 BC. Genetic analysis demonstrates that cultivated barley followed several different routes over time. By 4200 BC domesticated barley had reached Eastern Finland. Barley has been grown in

6480-508: The outer chloroplast membrane can use ATP to add a phosphate group to the Toc34 protein, preventing it from being able to receive another GTP molecule, inhibiting the protein's activity. This might provide a way to regulate protein import into chloroplasts. Arabidopsis thaliana has two homologous proteins, AtToc33 and AtToc34 (The At stands for A rabidopsis t haliana ), which are each about 60% identical in amino acid sequence to Toc34 in peas (called ps Toc34). AtToc33

6570-402: The plant's nuclear genome. The two RNA polymerases may recognize and bind to different kinds of promoters within the chloroplast genome. The ribosomes in chloroplasts are similar to bacterial ribosomes. RNA editing is the insertion, deletion, and substitution of nucleotides in a mRNA transcript prior to translation to protein. The highly oxidative environment inside chloroplasts increases

6660-399: The plastid-encoded RNA polymerase complex that are involved in plastid gene expression. The large Rubisco subunit and 28 photosynthetic thylakoid proteins are encoded within the chloroplast genome. Over time, many parts of the chloroplast genome were transferred to the nuclear genome of the host, a process called endosymbiotic gene transfer . As a result, the chloroplast genome

6750-400: The polypeptide from folding prematurely. This is important because it prevents chloroplast proteins from assuming their active form and carrying out their chloroplast functions in the wrong place—the cytosol . At the same time, they have to keep just enough shape so that they can be recognized and imported into the chloroplast. The heat shock protein and the 14-3-3 proteins together form

6840-760: The precursors of proteins , are chains of amino acids . The two ends of a polypeptide are called the N-terminus , or amino end , and the C-terminus , or carboxyl end . For many (but not all) chloroplast proteins encoded by nuclear genes, cleavable transit peptides are added to the N-termini of the polypeptides, which are used to help direct the polypeptide to the chloroplast for import (N-terminal transit peptides are also used to direct polypeptides to plant mitochondria ). N-terminal transit sequences are also called presequences because they are located at

6930-466: The predominant view today is that most cpDNA is circular. When the original experiments on cpDNA were performed, scientists did notice linear structures; however, they attributed these linear forms to broken circles. If the branched and complex structures seen in cpDNA experiments are real and not artifacts of concatenated circular DNA or broken circles, then a D-loop mechanism of replication is insufficient to explain how those structures would replicate. At

7020-421: The rate of mutation so post-transcription repairs are needed to conserve functional sequences. The chloroplast editosome substitutes C -> U and U -> C at very specific locations on the transcript. This can change the codon for an amino acid or restore a non-functional pseudogene by adding an AUG start codon or removing a premature UAA stop codon. The editosome recognizes and binds to cis sequence upstream of

7110-431: The rest of the chloroplast genome, as chloroplast DNAs which have lost some of the inverted repeat segments tend to get rearranged more. Each chloroplast contains around 100 copies of its DNA in young leaves, declining to 15–20 copies in older leaves. They are usually packed into nucleoids which can contain several identical chloroplast DNA rings. Many nucleoids can be found in each chloroplast. Though chloroplast DNA

7200-426: The same time, homologous recombination does not explain the multiple A → G gradients seen in plastomes. This shortcoming is one of the biggest for the linear structure theory. The movement of so many chloroplast genes to the nucleus means that many chloroplast proteins that were supposed to be translated in the chloroplast are now synthesized in the cytoplasm. This means that these proteins must be directed back to

7290-454: The song, John Barleycorn is represented as suffering attacks, death, and indignities that correspond to the various stages of barley cultivation, such as reaping and malting; but he is revenged by getting the men drunk: "And little Sir John and the nut-brown bowl / Proved the strongest man at last." The folksong " Elsie Marley " celebrates an alewife of County Durham with lines such as "And do you ken Elsie Marley, honey? / The wife that sells

7380-447: The stroma. Toc34's job is to catch some chloroplast preproteins in the cytosol and hand them off to the rest of the TOC complex. When GTP , an energy molecule similar to ATP attaches to Toc34, the protein becomes much more able to bind to many chloroplast preproteins in the cytosol . The chloroplast preprotein's presence causes Toc34 to break GTP into guanosine diphosphate (GDP) and inorganic phosphate . This loss of GTP makes

7470-447: The transit sequence forms a random coil. Not all chloroplast proteins include a N-terminal cleavable transit peptide though. Some include the transit sequence within the functional part of the protein itself. A few have their transit sequence appended to their C-terminus instead. Most of the polypeptides that lack N-terminal targeting sequences are the ones that are sent to the outer chloroplast membrane , plus at least one sent to

7560-435: The two complexes at the same time, but the TIC complex can also retrieve preproteins lost in the intermembrane space . Like the TOC translocon , the TIC translocon has a large core complex surrounded by some loosely associated peripheral proteins like Tic110 , Tic40 , and Tic21 . The core complex weighs about one million daltons and contains Tic214 , Tic100 , Tic56 , and Tic20 I , possibly three of each. Tic20

7650-559: The upper end of this range, each being 20,000–25,000 base pairs long. The inverted repeat regions usually contain three ribosomal RNA and two tRNA genes, but they can be expanded or reduced to contain as few as four or as many as over 150 genes. While a given pair of inverted repeats are rarely completely identical, they are always very similar to each other, apparently resulting from concerted evolution . The inverted repeat regions are highly conserved among land plants, and accumulate few mutations. Similar inverted repeats exist in

7740-584: The west to Tibet in the east. A study of genome-wide diversity markers found Tibet to be an additional center of domestication of cultivated barley. The earliest archaeological evidence of the consumption of wild barley , Hordeum spontaneum , comes from the Epipaleolithic at Ohalo II at the southern end of the Sea of Galilee , where grinding stones with traces of starch were found. The remains were dated to about 23,000 BC. The earliest evidence for

7830-412: Was 155 million tonnes, led by Russia accounting for 15% of the world total (table). France, Germany, and Canada were secondary producers. Worldwide barley production was fourth among grains, following maize (1.2 billion tonnes), wheat (808 million tonnes), and rice (776 million tonnes). Barley is a crop that prefers relatively low temperatures, 15 to 20 °C (59 to 68 °F) in the growing season; it

7920-940: Was by hand with sickles or scythes ; in developed countries, harvesting is mechanised with combine harvesters . Among the insect pests of barley are aphids such as Russian wheat aphid , caterpillars such as of the armyworm moth , barley mealybug , and wireworm larvae of click beetle genera such as Aeolus . Aphid damage can often be tolerated, whereas armyworms can eat whole leaves. Wireworms kill seedlings, and require seed or preplanting treatment. Serious fungal diseases of barley include powdery mildew caused by Blumeria graminis , leaf scald caused by Rhynchosporium secalis , barley rust caused by Puccinia hordei , crown rust caused by Puccinia coronata , various diseases caused by Cochliobolus sativus , Fusarium ear blight , and stem rust ( Puccinia graminis ). Bacterial diseases of barley include bacterial blight caused by Xanthomonas campestris pv. translucens . Barley

8010-428: Was named as H. distichon , six-row barley with nonshattering spikes as H. vulgare (or H. hexastichum ), and six-row with shattering spikes as H. agriocrithon . Because these differences were driven by single-gene mutations, coupled with cytological and molecular evidence, most recent classifications treat these forms as a single species, H. vulgare . Hulless or "naked" barley ( Hordeum vulgare var. nudum )

8100-646: Was used as currency. The Sumerian language had a word for barley, akiti . In ancient Mesopotamia , a stalk of barley was the primary symbol of the goddess Shala . Rations of barley for workers appear in Linear B tablets in Mycenaean contexts at Knossos and at Mycenaean Pylos . In mainland Greece, the ritual significance of barley possibly dates back to the earliest stages of the Eleusinian Mysteries . The preparatory kykeon or mixed drink of

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