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GBA Biochemistry > Open Answers (Ben and Dustin) > Flashcards

Open Answers (Ben and Dustin) Flashcards

1
Q

What is the Km difference between Glucokinase and Hexokinase?

A

Glucokinase: High Km, around 10 mM (low affinity)

Hexokinase: Low Km, less than 1 mM (high affinity)

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2
Q

3 ways to decrease blood cholesterol levels:

A
  1. Inhibit cholesterol synthesis via Statins
  2. Activate LCAT
  3. Low cholesterol diet
  4. Increase LDL receptor numbers
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3
Q

Metabolic effects of LXR (its function)

A
  1. Bile acid synthesis increased
  2. Cholesterol Efflux increased
  3. LDL receptor density decreased (ubiquination of LDLR’s)
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4
Q

What are the enzymes in carbohydrate metabolism that are responsible for insulin secretion from pancreatic beta cells?

A

Glucokinase and PFK-1

weird question. basically, glycolysis regulating enzymes

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5
Q

What happens to the rate of glycolysis during hypoxia?

What enzyme determines the rate of this state?

What regulates this? What hormones regulate it?

A

Increases

PFK-1 determines

PFK-2 upregulates PFK-1, and PFK-2 is regulated by insulin (stimulated) and glucagon (inhibited)

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6
Q

Allosteric Activators and Inhibitors of PFK1:

A

Activators: AMP + Fructose 2,6 Bisphosphate (the most potent activator)

Inhibitors: ATP + Citrate

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7
Q

What enzyme produces GTP in the TCA cycle?

A

Succinyl-CoA synthetase

(that name describes the reverse reaction to the normal order of the TCA cycle. the enzyme is also known as Succinate Thiokinase)

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8
Q

Substrates, products, and coenzymes of Methylmalonyl CoA Racemase

A

Substrate: D-methylmalonyl-CoA

Product: L-methylmalonyl-CoA

don’t know about coenzymes

(racemases are also called epimerases bc they just convert between epimers)

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9
Q

Substrate, product, coenzymes of Methylmalonyl CoA Mutase

A

Substrate: L-methylmalonyl-CoA

Product: Succinyl CoA (which can enter TCA cycle)

Coenzyme: Enzyme form of Vitamin B12 (deoxyadenosyl cobalamin)

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10
Q

Substrates and Products of Pyruvate Dehydrogenase

A

Substrate: Pyruvate, S-CoA, NAD+

Product: Acetyl-CoA, CO2, NADH + H

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11
Q

Which organs and tissues primarily use glucose from glycolysis for energy?
(I hope this is just worded badly and means which organs depend mostly on glucose for energy and not other substrates)

A

Red blood cells, testis, brain, adrenal medulla, cornea

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12
Q

What organs will be affected by glycogen storage disease?

A

Liver, skeletal muscle

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13
Q

Name an inhibitor of mitochondrial ATP synthase

A

Oligomycin

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14
Q

Substrates, products, cofactors of IMP dehydrogenase

A

Substrate: IMP, H2O, NAD+

Product: Xanthosine Monophosphate, NADH + H

Don’t know cofactors

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15
Q

What is the major protein for LDL?

A

B100

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16
Q

Explain the monosaccharide bond between units of glycogen

A

Elongation: alpha 1-4 bonds
Branching: alpha 1-6 bonds

17
Q

Explain the monosaccharide unit and bond between them in sucrose:

A

Glucose: alpha 1 carbon

to Fructose: 2 beta carbon

18
Q

Explain the monosaccharide unit and bond between them in Lactose

A

Galactose: beta 1 carbon
Glucose: beta 4 carbon

19
Q

Position and configuration of the OH group in primary bile acids:

A

3 alpha, 7 alpha, 12 alpha

all are in alpha configuration

20
Q

Substrate, Product, and Coenzyme of Threonine Dehydratase:

A

Substrate: Threonine

Product: alpha ketobutyrate + ammonia

Cofactor: PLP

21
Q

Substrate, Product, Coenzyme of Glycogen phosphorylase:

A

Substrate: Glycogen, Pi

Product: Glucose 1-P

Coenzyme: not sure, but debranching enzyme and alpha 1,6 glucosidase are necessary to continue going

22
Q

Precursors of LDL? Via what enzyme?

A

LDL comes from IDL (and VLDL before that) via Hepatic Lipase

23
Q

How many ATP are produced in the TCA cycle?

A

3 NADH -> 9 ATP
1 FADH2 -> 2 ATP
1 GTP -> 1 ATP

So 12 per acetyl-CoA, 24 per glucose molecule

24
Q

What is the intermediate in FA synthesis? Prosthetic group?

A

Intermediate: Malonyl-ACP

Prosthetic Group: ACP (acyl carrier protein)

25
Q

What enzymes in FA synthesis reduce NADPH?

A

3 ketoacyl-ACP reductase

Enoyl Reductase

26
Q

Enzymes responsible for covalent modification of PDH:

A

Pyruvate Dehydrogenase Kinase: inhibits PDH

Pyruvate Dehydrogenase Phosphatase: activates/removes the inhibiting phosphates of PDH

27
Q

What is the cofactor of Complex I in oxidative phosphorylation?

A

NADH

28
Q

What does PP1 (protein phosphatase 1) do?

A
  1. Removes phosphate from glycogen phosphorylase kinase (inhibition)
  2. Removes phosphate from glycogen phosphorylase (inhibition)
  3. Removes phosphate from glycogen synthase (activation)
29
Q

What does phosphoglucomutase do?

A

Converts 3-phosphoglycerate to 2-phosphoglycerate (reversible)

30
Q

What enzyme in glucose metabolism is located in the ER membrane?

A

Glucose 6 Phosphatase

GBA Biochemistry (6 decks)

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