Term
carbohydrates
cellular functions of carbs |
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Definition
compounds associated with polyhydroxy aldehydes and ketones.
they are the most abundant biomolecules in nature.
functions: energy, structure (as cellulose), communication adn precursors for other biomolecules. are a direct link between solar energy and chemical bond energy. |
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Definition
| the storage of carbs in animals is glycogen. it is a branched chain polymer like amylopectin but it has more frequent branching (about every 10 residiues). glycogen is stored in liver and muscle cells. |
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Definition
| enzyme that forces CO2 and h20 to catalyze. found in plants. uses photosynthesis energy to bond CO2 and h2o. very slow. |
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Definition
1. monosaccharides glucose and fructore serve as fuel molecules.
2. polysac starch and glycogen serve as chemical energy stores.
3. polysac such as cellulose, chitin, petidoglycan, etc serve as structural and protective structures.
4. monosacc ribose and deoxyribose are used in nucleotides and nucleic acids in RNA and DNA
5. glycoproteins are used for recognition. (proteins modified with glycan) |
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Definition
cars are classified by the number of carbon atoms they contain: trioses, tetroses, petoses and hexoses.
msot abundant are hexoes and pentoses
class names often compbine info about carbon number and functional group. |
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Definition
is an aldotriose.
exists in two stereoisomeric forms because the central carbon is a stereocenter: it has 4 different groups attatched. |
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Term
| designation of steroisomers |
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Definition
D isomer has OH on the sterocenter to the right. L isomer has the OH on the left.
they are designated according to the chiral carbon distal to the carbonyl. |
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Term
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Definition
naturally occuring monosaccs contain between 3 to 7 carbons.
trioses include glyceraldehyde and dihydroxyacetone.
monosaccs contain chiral centers and exist as stereoisomers called enantiomers. |
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Definition
stereoisomers that are NOT enantiomers (mirror images).
diastereomers that differ at a single chiral carbon are EPIMERS.
go over slide for examples. |
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Definition
| enzyme that is used to convert between diastereomers and epimers (a specific type of diastereomer) |
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Definition
| the msot simple sugars of 4 or more carbons exist in the cyclic form. if OH faces down it is hemiacetal. Hemiketal face upward. |
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Definition
| A hydroxyl group reacts with an alcohol. The new OH bearing carbon is not a stereocenter and is called an anomerica carbon. |
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Term
| Alpha v. Beta Carbons in cyclic sugars |
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Definition
If the OH on the ring is up the carbon is Beta. In fisher projections it is on the Left.
If the OH group is down, it is Alpha. Fischer group it is on the Right.
This applies only the the C closest to the O found in the sugar ring. |
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Term
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Definition
Pyranose resembles pyran in that it is a 6 membered ring, one of them being an O.
Furanose resembles Furan as a 5 membered ring, one of which is O.
ex: ribose yields ricofuranose.
fructore yields fructofuranose. |
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Term
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Definition
| the alpha and beta forms of cyclic sugars are said to be anomers. They differ in configuration about the hemiacetal or hemiketal carbon. when dissolved in water, alpha and beta forms are in equilibrium. this is known as mutarotation. |
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Term
| conformational v. hawthorne structures |
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Definition
| confirmational are more accurate than hawthorne because they show puckered rings. |
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Term
| 5 types of monosaccharide reactions |
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Definition
1. oxidation/reduction
2. isomerization
3. esterification
4. amino derivatives
5. glycoside formation and disaccharides. |
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Term
| Oxidation reduction of monosaccharaides |
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Definition
| oxidation is loss of H and reduction is addition of O. |
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Term
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Definition
carboxylic carbonyl groups in aldonic and uronic acids can react with OH groups to form a cyclic ester called Lacton.
Lactons are readily produced in nature, for example L-ascorbic acid (Vitamin C). Vit C is a powerful reducing agent that protects cells from reactive oxygen and nitrogen species (ROS,NOS) |
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Definition
| Sugars that can be oxidized by weak oxidizing agents such as Benedict's reagent are called reducing sugars. Needs open chain so all monosaccs are reducing sugars. all monosaccs with anameric C are reducing sugars. |
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Term
| Reduction of Monosaccs (alditols) |
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Definition
| the most imporant reduced sugar is deoxyribose. when the carbonyl of a sugar is reduced to an alcohol, Alditols are produced. |
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Term
| Isomerizatin of Monosaccs |
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Definition
| occurs through an enediol |
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Definition
| the O groups of sugars can react with phsophoric acid to give phosphate esters. major player in glycolysis. |
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Definition
free OH groups of carbohydrates can be converted to esters by reactions with acids.
esterification often dramatically changes a sugar's chemical and physical properties. |
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Definition
| sulfate esters of carbohydrate molecules are found predominantly in the proteoglycan components of connective tissue. they aprticipate in forming salt bridges between carbohydrate chain. creates very stable gel like structures. |
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Term
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Definition
attach sugars or glycans (sugar polymers) to proteins or lipids. occur because lots of glucose in blood.
catalyzed by glycosyl transferases, glycosidic bonds are formed between anomeric carbons in certain glycans and O and N or other types of molcules. resulting in N- or O- glycosidic bonds |
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Term
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Definition
smaller glycans made of 10-15 monomers called oligosaccharaides, most often attached to polypeptides as glycoproteins. 2 types are N and O.
N linkages form between oligosaccharaides and the side chain amide nitrogen Asparagine.
O linkages attach glycans to hydroxyl groups of serine or threonine residues or the hydroxyl oxygens of membrane lipids. |
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Term
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Definition
the reactions of reducing sugars with nucleophilic nitrogen atoms in a nonenzymatic reaction, eg the nonenzymatic glycation of protein.
olysaccs (glycans) are composed of monosacc monomers connected by glycosidic linkages. |
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Term
| Amadori Product and AGEs (glycations) |
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Definition
the schiff base that forms rearranges to stable ketoamine, called the Amadori product, causes proteins to cross link together.
can further react to form Advanced Glycation End (AGE) products that promote inflammatory processes. in diabetics |
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Term
| 3 sugars that make up 90% |
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Definition
alpha-D-glucose
alpha-D-galactose
beta-D-fructose |
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Term
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Definition
| D-glucose, originally called dextorse, found in large quantities throughout the natural world. primary fuel for living cells. preferred energy source for brain cells and cells without mitochondria (erythrocytes). |
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Term
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Definition
| D-fructose, often referred to as fruit sugar because of its high concentration in fruit. on a per gram basis it is twice as sweet as sucrose therefore it is often used as a sweetening agent in processed food. sperm use sugar as energy source. |
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Term
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Definition
galactos is necessary to synthesize a variety of limportant biomolecules; Lactose, glycolipics, phospholipids, proetoglycan, and glycoproteins.
Epimerase can interconvert glucose and galactose. Galactosemia is a genetic diroder resulting from a missing enzyme in galactose metabolism |
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Term
| Monosaccharide Derivatives |
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Definition
Uronic Acids- alpha D glucuronate and its epimer beta L are important in animals.
D glucuronic acid is used in the liver to improve water solutbility to remove waste molecules.
Amino sugars- a hydroxyl group (usually on c2) is replaced with an amine group.
D-glucosamine and D-glactosamine are most common, often attached to proteins or lipids. |
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Term
| monosacc derivatives cont'd |
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Definition
deoxy sugars are monosaccs that have an OH replaced by an H or CH3
2-deoxy-D-ribose is the pentose sugar of DNA and fucose is part of ABO blood group |
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Definition
| the anomeric carbon in a carbohydrate can react with an alcohol to form a glycosidic bond. if the bond is formed between 2 monosacc, a disacc is formed. linkage to the anomeric carbon can be either alpha or b, creating ISomers! |
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Term
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Definition
maltose is formed by linking two alpha D glucose molecules to give an alpha 1,4 glycosidic link.
maltose is an intermediate product of starch hydrolysis. |
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Term
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Definition
larger glycans may be hundreds or thousands of subunits, called polysaccharides. can be linear or branched.
divided into 2 classes: homoglycans and heteroglycans.
homoglycans have 1 types of monosacc, are found in starch glycogen cellulose and chiting.
1 and 2 are storage molecules while 3 and 4 are structural |
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Term
| disaccharaides: Cellubiose and Sucrose |
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Definition
cellubiose is formed by linking two beta D glucose molecules to give a beta 1,4 glycosidic link.
it comes from hydrolized cellulose.
sucrose is formed by linking alpha D glucose with beta D fructose to give a 1,2 glycosidic link. glycosidic bond occurs between both anomeric carbons, thus nonreducing. becuase no free anameric Carbons. |
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Term
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Definition
formed by joining beta D galactose to alpha D glucose to give a beta 1,4 glycoside.
mutarotation gives alpha and beta isomers. lactose is milk sugar. lactase deficiency is common. lactose is a reducing sugar. |
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Term
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Definition
cellulose is the major structural polymer in plants. it is linear homopolymer composed of beta D glucose units linked beta 1,4. the repeating disacc of cellullose if beta cellobiase. bacteria in ruminants can digest cellulose so that they can eat grass, etc.
pairs of unbranched cellulose molecules (12,000 units each) are help together by hydrogen bonding to form sheet like strips, or microfibrils. each microfibril bundle may contain 40 pairs. |
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Term
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Definition
| a lineat homopolysacc of N-acetyl-beta-D-glucosamine and provides structural support for the exoskeleton of invertebrates. the polymer is linked as beta 1,4 unites. |
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Term
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Definition
| high molecular weight carb polymers that contain more than one type of monosac. major types: N and O linked glycosaminoglycans, glycan parts of lycolipids and GPI anchors (glycosylphosphatidylinositol). |
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Term
| GAGs or mucopolysaccharides |
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Definition
| glycosaminoglycans are linear polymers with a disaccharide repeating units. ex: chondroitin sulfate, a component of cartilage. |
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Definition
are compounds that covalently link carbs to proteins and lipids.
proteoglycans and glycoproteins are two kinds that contain protein. |
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Definition
have a very high carb to protein ratio, often 95:5. found in extracellular matrix. GAG chains are linked to core proteins by N and O glycosidic links.
have roles in organzing extracellular matrix and are involved in signal transduction.
metabolism of prteoglycans involved in many genetic disorders (hurler's syndrome) |
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Term
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Definition
| these materials contain carb residues on protein chains. very important examples of these materials are antibodies- chemicals which bind to antigens and immobilize them. the carb part of the glycoproteins plays a role in determining the aprt of the antigen molecule to which the antibody binds. |
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Term
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Definition
living organisms require large coding capacities for info transer. profound complexity of functioning systems.
to succeed as a coding mechanism, a class of molecules must have a large capacity for variation. glycosylation is the most important posttranslational modification in terms of coding capacity.
GP120 - HIV receptor. |
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Term
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Definition
or carb binding proteins, are involved in translating the sugar code.
bind specifically to the carb via hydrogen bonding, van der waals forces, and hydrophoic interactions.
functions: binding to bacteria, viruses, toxins, leukocyte rolling, and many others. |
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Term
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Definition
the total set of sugars and glycans in a cell or organism.
constantly in flux depending on the cell's response to environment.
there is no template for glycan biosynthesis; it is done in a stepwise process.
glycoforms can result based upon slight varioations in glycan composition of each glycoprotein. |
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Term
| stage 1 glocuse to dihydroxyacetone phophate + glyceraldehyde-3-phosphate |
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Definition
glucoe --> glucose-6-phosphate --> fructose-6-phosphate --> fructose-1,6-bisphosphate --> dihydroxyacetone phophate + glyceraldehyde-3-phosphate
is run twice. in 1st step, energy released, used to create phos bond.
Inorganic phosphate requires energy input to create phosphate bond |
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Term
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Definition
1- energy investment (uses atp, activates glucose, thermo unstability) steps 1-5
2- ATP production. steps 6-10 |
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Term
| the anaerobic aoxidation of glucose (G) to give molucules of pyruvate |
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Definition
Glucose + 2ADP + 2Pi + 2NAD+ --> 2 Pyruvate + 2ATP + 2NADH + 2H+ + 2h2o
overall ATP production is 2. but use 2 in process and create 4. |
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Term
| stage 2 glyceraldehyde-3-phosphate to pyrvuate |
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Definition
| glyceraldehyde-3-phosphate --> glycerate-1,3-bisphosphate --> glycerate-3-phosphate --? glycerate-2-phosphate --> phosphoenolpyruvate --> pyruvate |
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Term
| individiual steps of glycolysis #1 |
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Definition
synthesis of glucose into glucose-6-phosphate: phosphorylation of glucose (hexokinase, Mg2+) prevents transport out of the cell and increases reactivity.
Mg2+ is a cofactor because ATP is onvolved. is divalent cation which can bridge between 2- bonds of atp, therefor it is stabilized. |
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Term
| individiual step of glycolysis #2 |
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Definition
conversion of glucose-6-phosphate to fructose-6-phosphate, via phosphoglucose isomerase. (conversion of aldose to ketose)
does not require atp, deltaG is +. fructose is consumed therefore equilibrium is shifted so deltaG is - in cell. |
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Term
| individiual step of glycolysis #3 |
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Definition
phosphorylation of fructose-6-phosphate. this step is irreversible due to a large decrease in free energy and commits molecule to glycolysis. done via phosphofructokinase-1 (PFK-1). this is irreversible hydrolayses of atp. a major regulatory enzyme.
the commited step (irreversible). PFK-1 is a tetrameric enzyme as M4 in muscle or L4 in liver.
Allosteric effectors: high atp concentration ddepresses rate fructose-2,6-bisP activates (PFK-1) |
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Term
| individiual step of glycolysis #4 |
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Definition
cleavage of fructose-1,6-bisP to dihydroxyacetone phosphate and D-glyeraldehyde-3-phosphate. aldol cleavage giving an aldose and ketose product. done via aldolase.
very little energy transferred, practically in equilibrium. |
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Term
| individiual step of glycolysis #5 |
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Definition
| interconversion of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. conversion of aldose to ketose enables all carbons to continue through glycolysis. done via triosephophate isomerase. |
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Term
| individiual step of glycolysis #6 |
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Definition
oxidation of glyceraldehyde-3-P to glycerate-1,3-bisphosphate. done in 2 steps. creates high energy phosphoanhydride bond for atp formation of NADH.
done via glyceraldehyde-3-phosphate dehydrogenase.
a phosphorylation and a 2 electron oxidation by NAD+ occur.
2 steps. 1. glyceraldehyde --> 3-P-glycerate. -43.1kJ step 2. 3-P-glycerate + HPO4 --> glycerate-1,3-bidP at +49.3kJ
its +deltaG but ok because product is used up to change the deltaG, dragging reaction forward. |
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Term
| oxidation in step 6 of glycolysis |
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Definition
oxidation of glyceraldehyde-3-P is a 2 step process. 1 G-3-P undergoes oxidation and phosphorylation. 2. G-3-P interacts with sulfhydral group in the enzyme's active site, forms thioester. high energy bond that can be used to drive reaction forward.
highly unstable, increases phosphate transfer. |
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Term
| individiual step of glycolysis #7 |
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Definition
phophoryl group transfer. prudction of atp via substrate-level phosphorylation (aka atp production). energy of oxidation in step 6-7 is conserved in ATP.
phosphoglycerate kinase, Mg2+ creates glycerate-3-phosphate and atp from g-1,3,-p and adp. |
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Term
| individiual step of glycolysis #8 |
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Definition
| interconversion of 3-phosphoglycerate and 2-phosphoglycerate. first step in formation od phosphoenolpyruvate (PEP). done via phosphoglycerate mutase and Mg2+ (stabilizes enzyme). this step is considered unstable. |
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Term
| individiual step of glycolysis #9 |
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Definition
dehydration of 2-phosphoglycerate. production of PEP, which has a high phosphoryl group transfer potential (tautomerization), locks it into the highest energy form. done via enolase, Mg2+. highly unstable, lots of phosphate group transfer potential.
step 8 and 9 boost energy in order to form more atp. |
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Term
| individiual step of glycolysis #10 |
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Definition
formatin of pyruvate and atp. produces a net of 2 atp, 2 nadh and 2 pyruvate.
done via pyruvate kinase, Mg2+.
irreversible, makes very good site for ___ |
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