Open Answers (Final) Flashcards
What is the Km difference between Glucokinase and Hexokinase?
Glucokinase: High Km, around 10 mM (low affinity)
Hexokinase: Low Km, less than 1 mM (high affinity)
3 ways to decrease blood cholesterol levels:
- Inhibit cholesterol synthesis via Statins
- Activate LCAT
- Low cholesterol diet
- Increase LDL receptor numbers
Metabolic effects of LXR (its function)
- Bile acid synthesis increased
- Cholesterol Efflux increased
- LDL receptor density decreased (ubiquination of LDLR’s)
What are the enzymes in carbohydrate metabolism that are responsible for insulin secretion from pancreatic beta cells?
Glucokinase and PFK-1
weird question. basically, glycolysis regulating enzymes
What happens to the rate of glycolysis during hypoxia?
What enzyme determines the rate of this state?
What regulates this? What hormones regulate it?
Increases
PFK-1 determines
PFK-2 upregulates PFK-1, and PFK-2 is regulated by insulin (stimulated) and glucagon (inhibited)
Allosteric Activators and Inhibitors of PFK1:
Activators: AMP + Fructose 2,6 Bisphosphate (the most potent activator)
Inhibitors: ATP + Citrate
What enzyme produces GTP in the TCA cycle?
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)
Substrates, products, and coenzymes of Methylmalonyl CoA Racemase
Substrate: D-methylmalonyl-CoA
Product: L-methylmalonyl-CoA
don’t know about coenzymes
(racemases are also called epimerases bc they just convert between epimers)
Substrate, product, coenzymes of Methylmalonyl CoA Mutase
Substrate: L-methylmalonyl-CoA
Product: Succinyl CoA (which can enter TCA cycle)
Coenzyme: Enzyme form of Vitamin B12 (deoxyadenosyl cobalamin)
Substrates and Products of Pyruvate Dehydrogenase
Substrate: Pyruvate, S-CoA, NAD+
Product: Acetyl-CoA, CO2, NADH + H
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)
Red blood cells, testis, brain, adrenal medulla, cornea
What organs will be affected by glycogen storage disease?
Liver, skeletal muscle
Name an inhibitor of mitochondrial ATP synthase
Oligomycin
Substrates, products, cofactors of IMP dehydrogenase
Substrate: IMP, H2O, NAD+
Product: Xanthosine Monophosphate, NADH + H
Don’t know cofactors
What is the major protein for LDL?
B100
Explain the monosaccharide bond between units of glycogen
Elongation: alpha 1-4 bonds
Branching: alpha 1-6 bonds
Explain the monosaccharide unit and bond between them in sucrose:
Glucose: alpha 1 carbon
to Fructose: 2 beta carbon
Explain the monosaccharide unit and bond between them in Lactose
Galactose: beta 1 carbon
Glucose: beta 4 carbon
Position and configuration of the OH group in primary bile acids:
3 alpha, 7 alpha, 12 alpha
all are in alpha configuration
Substrate, Product, and Coenzyme of Threonine Dehydratase:
Substrate: Threonine
Product: alpha ketobutyrate + ammonia
Cofactor: PLP
Substrate, Product, Coenzyme of Glycogen phosphorylase:
Substrate: Glycogen, Pi
Product: Glucose 1-P
Coenzyme: not sure, but debranching enzyme and alpha 1,6 glucosidase are necessary to continue going
Precursors of LDL? Via what enzyme?
LDL comes from IDL (and VLDL before that) via Hepatic Lipase
How many ATP are produced in the TCA cycle?
3 NADH -> 9 ATP
1 FADH2 -> 2 ATP
1 GTP -> 1 ATP
So 12 per acetyl-CoA, 24 per glucose molecule
What is the intermediate in FA synthesis? Prosthetic group?
Intermediate: Malonyl-ACP
Prosthetic Group: ACP (acyl carrier protein)
What enzymes in FA synthesis reduce NADPH?
3 ketoacyl-ACP reductase
Enoyl Reductase
Enzymes responsible for covalent modification of PDH:
Pyruvate Dehydrogenase Kinase: inhibits PDH
Pyruvate Dehydrogenase Phosphatase: activates/removes the inhibiting phosphates of PDH
What is the cofactor of Complex I in oxidative phosphorylation?
NADH
What does PP1 (protein phosphatase 1) do?
- Removes phosphate from glycogen phosphorylase kinase (inhibition)
- Removes phosphate from glycogen phosphorylase (inhibition)
- Removes phosphate from glycogen synthase (activation)
What does phosphoglucomutase do?
Converts 3-phosphoglycerate to 2-phosphoglycerate (reversible)
What enzyme in glucose metabolism is located in the ER membrane?
Glucose 6 Phosphatase
