Biochem exam 2

glucose is a precursor to

RNA, DNA, fatty acids, amino acids

glucose is an important energy source for

brain, muscle cells, reproductive cells

glycolysis

metabolic pathway where glucose is oxidized to produce energy in the form of ATP

glycolysis has how many enzymatic steps

10

by-products of glycolysis

2 ATP and 2 NADH

NAD+/NADH and NADP+/NADHP are

coenzymes of various oxidoreductases

NAD+

oxidized form

NADH

reduced form

Glycolysis step 1

glucose to glucose 6-phosphate; first priming reaction; irreversible

glycolysis step 1 enzyme

hexokinase

glycolysis step 2 enzyme

phosphohexose isomerase

glycolysis step 3

fructose-6-phosphate to fructose 1,6-biphosphate; second priming reaction; irreversible

glycolysis step 4

fructose-1,6-biphosphate is cleaved to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate; reversible

glycolysis step 4 enzyme

aldolase

glycolysis step 5

glyceraldehyde 3-phosphate and dihydroxyacetone phosphate; reversible between 2 isomers

glycolysis step 5 enzyme

trios phosphate isomerase

glycolysis step 6 enzyme

glyceraldehyde-3-phosphate dehydrogenase

glycolysis step 6 oxidative and phosphorylation

2 inorganic phosphates are put into reaction; 2 NAD+ are made into 2 NADH and H

Glycolysis step 7

1,3-biphosphoglycerate (2) to 3-phosphoglycerate (2); first ATP (2) forming step; irrversible

glycolysis step 7 enzyme

phosphoglycerate kinase

glycolysis step 8

3-phosphoglycerate (2) to 2-phosphoglycerate (2); reversible

glycolysis step 8 enzyme

phosphoglycerate mutase

glycolysis step 9

2-phosphoglycerate (2) to phosphoenolpyruvate (2); reversible; H2O clevage

glycolysis step 9 enzyme

enolase

glycolysis step 10

phosphoenolpyruvate (2) to pyruvate (2); irreversible; second ATP (2) forming reaction

glycolysis step 10 enzyme

pyruvate kinase

2 pyruvate in presence of O2

6 CO2

2 pyruvate in yeast with low or no O2

ethanol + CO2

2 pyruvate in muscles with low or no O2

lactate

fermentation enzymes

pyruvate decarboxylase and acetaldehyde dehydrogenase

for glycolysis, NADH must be deoxidized to

NAD+

deregulation of glucose in solid tumors

glucose uptake is 10x faster, overproduction of hexokinase II, overproduction of GLUT1 and GLUT3; glycolysis is also 10x faster

deregulation of glucose in solid tumors therapeutic opportunity

Gleevec and adding F-18 to it so hexokinase is tricked into thinking it is a sugar which does not let it go any further in glycolysis

Gleevec

anti-cancer drug that inhibits over expression of hexokinase II in cancer cells

anaerobic energetics

1. 2 ATP used, 4 made

2. 2 NAD+ is byproduct

3. product is lactose

anaerobic fermentation or hypoxia energetics

1. 2 ATP used, 30-32 made

2. 10 NAD+ and 2 FAD+ is byproduct

3. product is CO2 and H2O

lactose

glucose and galactose

sucrose

glucose and fructose

maltose

glucose and glucose

glycogen

main storage form of glucose in our body

glycogen (starch) phosphorylase hydrolyzes (a1-4)

glycosidic bonds to produce glycose-2-P from glycogen or starch

enzyme used to convert pyruvate to acetyl CoA

pyruvate dehydrogenase

Pyruvate to acetyl CoA

irreversible oxidative decarboxylation step requires three enzymes and 5 coenzymes

PDH inactive

PDH with phosphate bonded

PDH inactive to active

phosphate is removed with help from PDH phosphatase

PDH active to inactive

ATP is broken down to add phosphate back to PDH

gluconeogensis

synthesis of glucose from non-carbohydrate substrates such as oxaloacetate or pyruvate

gluceogensis first bypass reaction

pyruvate to phosphoenol pyruvate

gluceogensis first bypass reaction enzymes

pyruvate carboxylase (mitochondria) and PEP carboxykinase (cytoplasm)

gluceogensis second bypass reaction

fructose-1,6-biphosphate to fructose 6-P; point of control for gluconeogensis

gluconeogensis second bypass reaction enzymes

fructose 1,6-biphosphate-1

gluconeogensis third bypass reaction

glucose-6-P to glucose

gluconeogensis third bypass reaction enzymes

glucose 6-phosphatase

pentose phosphate pathway functions

generate ribose-5-P and (re) generate NADPH

PPP step 1 enzyme

G-6-P dehydrogenase

PPP step 2 enzyme

6-P-glucolactonase

PPP step 3

6-phosphogluconate to ribulose-5-phosphate, NADP+ is reduced to NADPH + H

PPP step 3 enzyme

6-P-glucolactonate dehydrogenase

PPP step 4

ribulose-5-phosphate to ribose-5P

PPP step 4 enzyme

ribose-5P-isomerase

glycolysis step 2

glucose 6-phosphate to fructose-6-phosphate; reversibleg

glycolysis step 3 enzyme

phosphofructokinase-1

glycolysis step 6

glyceraldehyde 3-phosphate (2) to 1,3-biphosphoglycerate; reversible (2)

production of acetyl CoA: ultimate electron acceptor

NADH

gluconeogensis in humans occurs in

kidney and liver

pentose phosphate pathway

oxidative conversion of a C6 sugar to a C5 sugar

PPP step 1

glucose-6-P to 6-phosphoglucono-delta-lactone; NADP+ is reduced to NADPH +H

PPP step 2

6-phosphoglucono-delta-lactone to 6-phosphogluconate

what is a monosaccharide

carbohydrate with a single unit

how many carbons are in a monosaccharide (min and max)

3 min, 7 max

what is an aldose carbonyl

the end of a chain where the C=O is

what is a ketone carbonyl

any other position on the chain where the C=O is

L entiometric form

OH is left of carbonyl

D enantiomeric form

OH is right of carbonyl

what is a disaccharide

two+ monosaccharides linked via covalent glycosidic bond

examples of sucrose (glucose+fructose)

cane sugar, beet sugar

examples of lactose (glucose+galactose)

mother’s milk

examples of maltose (glucose+glucose)

hydrolyzed starch, fruit juices

what are polysaccharides

150+ units with high molecular weight, occurs in polymer form, and can be natural or synthetic

what is a carbohydrate

carbon and hydration (H2O); (CH2O)n

what are the 4 methods of classifying monosaccharides

carbonyl location (aldose, ketose), L/D enantiomeric forms, carbon count (triodes, tetroses, pentoses, hexoses, heptoses), and functional groups besides C,H,O

what is an aldose

H-C=O at end of carbon chain

what are examples of an aldose

d-erythrose, d-ribose, d-galactose, d-glucose

what is ketoses

C=O at any other position in the molecule

what are examples of ketoses

d-fructose, d-ribulose, d-erytrulose

why is glucose important

main source of energy, principal product of photosynthesis

what are 5 common modified forms of monosaccharides

deoxy sugars, amino sugars, acidic sugars, sugar esters, and sugar alcohols

what is an example of deoxy sugars

deoxyribose

what is the function of deoxy sugars

DNA structure

what is an example of amino sugars

glucosamine, galactosamine

what is the function of amino sugars

glycoprotein, glycolipid structure, and functions

what is an example of acidic sugars

ascorbic acid or vitamin C

what is the function of acidic sugars

oxidation-reduction reactions

what is an example of sugar esters

glucose-6 PO4

what is the function of sugar esters

metabolic reactions

what is an example of sugar alcohols

glycerol, erythritol, galactitol

what is a function of sugar alcohols

metabolic reactions

what is the structure of homo polysaccharides

extensive branching, compact structure, complex, alpha and beta conformations

what are types of homo polysaccharides

cellulose, starch, glycogen

what are types of hetero polysaccharides

peptidoglycan, glycosaminoglycan