biochemistry carbohydrates: exam 3

what is the difference between aldose and ketose?

an aldose has an aldehyde group and a ketose has a keto group

what are isomers?

they both have the same formula, but the location is different on each molecule

what is the difference between a D and L configuration?

a D configuration has an OH group on the right side of the fisher projection while an L configuration has an OH group on the left side of the fisher projection

what is an epimer

there is a difference between configurations around only one specific chiral carbon atom (ex. glucose and galactose are C-4 epimers)

what is cyclization of glucose?

the OH bond on C5 bonds with C1

what is the difference between alpha and beta

they refer to the locations of the OH group relative to the ring

how do you know if a monosaccharide is alpha or beta

if the monosaccharide is alpha the OH group will be on the bottom, and if it’s beta the OH group will be on the top

what makes up lactose

galactose and glucose

what makes up sucrose

glucose and fructose

what are the different polysaccharide formations

1-4 glycosidic bond and 1-6 glycosidic bond

what is catabolism

breaking down carbohydrates, fats, and proteins, produces ATP and NADH, poor products: water, CO2 and ammonia

what is anabolism

buildup of complex molecules: proteins, polysaccharides, lipids, nucleic acids, it uses ATP and NADH, produces precursor molecules: AAs, sugars, fatty acids, and nitrogenous bases

what is the first stage of catabolism

break down by enzymes in digestion of food

what is the second stage of catabolism

convert building blocks: AAs, monosaccharides, glycerol, and fatty acids into acetyl-CoA

what is the third step of catabolism

TCA cycle

where does aerobic respiration take place

it starts from glycolysis

what are the aerobic conditions for glucose

glucose is oxidized to CO2 and H2O

what is the overall reaction for glycolysis

glucose (6C) + 2NAD⁺ + 2ADP + 2Pi → 2 pyruvate (3C) + 2NADH + 2H + 2 net ATP

what is part of the energy investment phase

glucose → 2 ATP → 2ADP

what is part of the energy generation phase

4ADP -> 4ATP -> 2NAD+ -> 2NADH -> 2 pyruvate

what is the first step of glycolysis

hexokinase catalyzation: catalyzes glucose into glucose-6-phosphate using ATP by adding a phosphate group

what is the second step of glycolysis

isomerization of glucose: converts glucose-6-phosphate into fructose-6-phosphate

what is the third step of glycolysis

phosphofructokinase reaction: converts fructose-6-phosphate into fructose-1,6-bisphosphate by adding a phosphate group from ATP

what is the fourth step of glycolysis

fructose-1,6-bisphosphate is cleaved by aldolase into dihydroxyacetone phosphate and D-glyeraldehyde-3-phosphate

what is the fifth step of glycolysis

triose phosphate isomerase reaction: moves the location of the C=O bond

what is the rate limiting step of glucose

fructose-6-phosphate → fructose-1,6-bisphosphate

what is step 6 of glycolysis

glyceraldehyde phosphate (GAP) dehydrogenase reaction: ketotriose G3P gets further phosphorylated into 1,3-bisphosphateand oxidized and reduced NAD+ to NADH

what is step 7 of glycolysis

phosphoglycerate kinase reaction: converts 1,3-bisphosphoglycerate into 3-phosphoglycerate by removing a phosphate group

what is step 9 of glycolysis

2-phosphoglycerate is converted into phosphoenolpyruvate through enolase which combines the H and OH group from 2-phosphoglycerate into H2O

what is step 8 of glycolysis

3-phosphoglycerate is converted into 2-phosphoglycerate by moving a phosphate group from the third C-O bond to the second

what is step 10 of glycolysis

a phosphate group from phosphoenolpyruvate is given to ADP and is converted into pyruvate by pyruvate kinase and produces ATP

where does transporter GLUT-1 and GLUT-3 bring glucose and the function

brings it to most tissues for basal glucose uptake

where does transporter GLUT-4 bring glucose and the function

brings it to muscle and fat to remove excess glucose from blood

what are the points of regulation in glycolysis and why

hexokinase step and phosphofurctokinase-1 because they have irreversible catalyzation and are highly exergonic reactions

does glucokinase have a high or low vmax

high vmax

does hexokinase have a high or low vmax

low vmax

what happens to your glucagon and hepatic fructose-2,6-bisphosphate when you eat

glucagon levels decrease when insulin levels are increased, hepatic fructose-2,6-bisphosphate also increase

what happens glucagon and hepatic fructose-2,6-bisphosphate when you fast

glucagon levels increase when insulin levels are low which causes a decrease in hepatic fructose-2,6-bisphosphate which inhibits glycolysis and activation of gluconeogenesis

what happens when blood glucose levels are low

elevated glucagon levels increase cAMP which phosphorylates pyruvate kinase in the liver which leads to glycolysis stopping and gluconeogenesis starting

how is pyruvate kinase inactivated

phosphorylation by cAMP dependent PKA

what happens during anaerobic glycolysis

pyruvate is reduced to lactate in the muscles, the NADH/NAD+ ratio is very high with no net NADH, 5 less ATP are produced and 2 molecules of lactate are produced

how is pyruvate converted into acetyl-CoA

the molecule goes from 3 carbons to 2 carbons and NAD+ is reduced to NADH

what does coenzyme E1 do

it decarboxylates pyruvate into hydroxyl derivative

what does coenzyme E2 do

it oxidized hydroxyethyl intermediate into dihydrolipoly transacetylase

what does coenzyme E3 do

oxidizes sulfhydryl from lipoic acid by FAD-dependent dihydrolipoly dehydrogenase (E3)

what does E1 require

thiamine pyrophosphate

what does E2 require

lipoic acid and CoA

what does E3 require

FAD and NAD+

what is vitamin folic acids coenzyme product

tetrahydrofolate

what is vitamin lipoic acids coenzyme product

lipoamide

what is vitamin nicotinamides coenzyme product (B3)

nicotinamide coenzymes (NAD+ and NADH)

what is vitamin pantothermic acids coenzyme product (B5)

coenzyme A

what is vitamin riboflavin (B2) coenzyme product

flavin coenzymes (FAD and FMN)

what is vitamin thiamine (B1) coenzyme product

thiamine pyrophosphate

what deactivates E1

PDH kinase when it’s phosphorylated

what activates E1

when PDH phosphatase dephosphorylates

what is the goal of the citric acid cycle

produce 3NADH and 1 FADH2 to feed the ETC to produce ATP

how much ATP is produced in the TCA cycle

10 ATP/Acetyl-CoA oxidized

what enzymes regulate the citric acid cycle

citrate synthase, isocitrate dehydrogenase, and alpha-ketoglutarate dehydrogenase

true or false: citric acid cycle is exergonic

true

what molecules from food are oxidized

• acetyl-CoA→ fatty acids, AAs

• pyruvate→ carbohydrates and AAs

what are the amino acids in the TCA cycle

• alpha-ketoglutarate

• succinyl-CoA

• pyruvate

• fumarate

• oxaloacetate

is the citric acid cycle catabolic or anabolic

it is both which is called amphibolic

what is the difference between alanine and pyruvate

alanine has an NH3+ group attached to the second carbon while pyruvate has an oxygen double bonded to the second carbon

how are the A and B chains of insulin linked

linked through three cys-cys bonds

what are the different ways GLP-1 agonists works

• triggers insulin release from your pancreas and blocks secretion of glucagon

• prevents more glucose from going into your bloodstream

• slowing down digestion which leads to less glucose being released

• increase how full you feel after eating

what happens when blood glucose is low

• glucagon (hormone) is released to raise blood sugar

• glycogen (stored glucose) is released, stimulate gluconeogenesis

• stop glucose consumption

• glycolysis stops/slows down

what happens when blood glucose is high

• insulin (hormone) is released

• liver uses glucose as fuel

• glycolysis starts

• insulin triggers formation of fructose-2,6-bisphosphate and activation of PFK-1 and glycolysis

what all triggers the release of insulin from beta cells

glucose, amino acids, and fatty acids

what do oxidized compounds have

they have more bonds with oxygen such as carbon dioxide O=C=O

what do reduced compounds have

they have more bonds with hydrogens such as an alkane -CH2-CH3