BMB 401 Exam 3

What is the main purpose of the Citric Acid Cycle?

To produce NADH and FADH₂ for the Electron Transport Chain

What enters the Citric Acid Cycle?

Acetyl-CoA.

What is the first enzyme of the CAC?

Citrate Synthase.

What is the rate-limiting enzyme of the CAC?

Isocitrate Dehydrogenase.

Which CAC enzyme uses the same cofactors as Pyruvate Dehydrogenase?

α-Ketoglutarate Dehydrogenase.

What are the five cofactors shared by PDH and α-Ketoglutarate Dehydrogenase?

TPP, Lipoamide, CoA, FAD, NAD⁺.

Which CAC enzyme produces ATP (or GTP)?

Succinyl-CoA Synthetase.

Which CAC enzyme produces FADH₂?

Succinate Dehydrogenase.

Which ETC complex is also Succinate Dehydrogenase?

Complex II.

How many NADH are produced per turn of the CAC?

3

How many FADH₂ are produced?

1

How much ATP (GTP) is produced?

1 ATP

Which CAC steps are irreversible?

Citrate Synthase, Isocitrate Dehydrogenase, α-Ketoglutarate Dehydrogenase.

What activates the CAC?

ADP

What inhibits the CAC?

ATP and NADH

What is the purpose of the ETC?

To create a proton gradient

What is the final electron acceptor?

Oxygen

What is produced when oxygen accepts electrons?

Water

Which complexes pump protons?

Complexes I, III, and IV

Which complex does NOT pump protons?

Complex II does not pump protons

Where does NADH donate electrons?

Complex I

Where does FADH₂ donate electrons?

Donates to Complex II

ATP yield from one NADH?

2.5 ATP

ATP yield from one FADH₂?

1.5 ATP

What are ROS?

Reactive Oxygen Species.

Which enzyme converts superoxide into hydrogen peroxide?

Superoxide Dismutase

Which enzyme converts hydrogen peroxide into water?

Catalase

Which enzyme actually makes ATP?

ATP Synthase

What powers ATP Synthase?

Proton flow (H⁺ gradient).

What does the F₀ portion do?

Allows protons to flow.

What does the F₁ portion do?

Synthesizes ATP.

Which ATP synthase conformation binds ADP and Pi?

Loose

Which conformation makes ATP?

Tight

Which conformation releases ATP?

Open.

What is IF1?

Prevents ATP synthase from running backward

What does UCP1 do?

Produces heat instead of ATP.

Which poison blocks ATP Synthase?

Oligomycin.

Which poison blocks Complex IV?

Cyanide

Where is glycogen stored?

Liver and skeletal muscle

Liver glycogen is used for what?

Maintaining blood glucose.

Muscle glycogen is used for what?

Muscle energy.

What enzyme breaks glycogen apart?

Glycogen Phosphorylase.

What enzyme removes branches?

Debranching Enzyme.

What enzyme builds glycogen?

Glycogen Synthase.

What starts glycogen synthesis?

Glycogenin.

What activates Glycogen Phosphorylase?

Phosphorylation.

What happens to Glycogen Synthase when phosphorylated?

It becomes inactive

What hormone stimulates glycogen breakdown?

Glucagon

Which hormone stimulates glycogen synthesis?

Insulin

What does PP1 do?

Removes phosphates

McArdle Disease results from deficiency of which enzyme?

Muscle Glycogen Phosphorylase

What are the two major products of PPP?

NADPH and Ribose-5-Phosphate.

What is the rate-limiting enzyme?

G6PD

Why is NADPH important?

Protects against oxidative damage and supports fatty acid synthesis.

Why do RBCs need PPP?

They rely on NADPH to prevent oxidative damage

G6PD deficiency causes what?

Hemolytic anemia

Which vitamin does Transketolase require?

Thiamine (Vitamin B₁/TPP)

Oxidative phase produces what?

NADPH

Nonoxidative phase produces what?

Ribose-5-phosphate and glycolysis intermediates

What hormone stimulates lipolysis?

Glucagon

What carries fatty acids through blood?

Albumin.

What transports long-chain fatty acids into mitochondria?

Carnitine Shuttle.

Which enzyme loads fatty acids onto carnitine?

CPT I

Which enzyme removes carnitine?

CPT II

What is the purpose of β-oxidation?

Produce Acetyl-CoA

What is the order of β-oxidation

Oxidation → Hydration → Oxidation → Thiolysis

Every round of β-oxidation produces what?

1 NADH, 1 FADH₂, 1 Acetyl-CoA

What is the final product of odd-chain fatty acids?

Propionyl-CoA

Which vitamin converts Propionyl-CoA to Methylmalonyl-CoA?

Biotin

Which vitamin converts Methylmalonyl-CoA to Succinyl-CoA?

Vitamin B₁₂

What are ketone bodies made from?

Excess Acetyl-CoA

Which organ makes ketone bodies?

Liver

Which organ cannot use ketone bodies?

Liver.

Where does fatty acid synthesis occur?

Cytoplasm

What carries acetyl-CoA out of mitochondria?

Citrate

What is the rate-limiting enzyme?

Acetyl-CoA Carboxylase (ACC1)

ACC1 converts acetyl-CoA into what?

Malonyl-CoA.

Which vitamin does ACC1 require?

ACC1 requires Biotin

What activates ACC1?

Citrate and insulin

What inhibits ACC1?

Glucagon, epinephrine, and AMPK

What enzyme builds fatty acids

Fatty Acid Synthase

What is the main product of Fatty Acid Synthase?

Palmitate (16 carbons)

Where are fatty acids longer than 16 carbons made?

Endoplasmic Reticulum

Which fatty acids are essential?

Linoleic acid and Linolenic acid

Arachidonic acid is the precursor for what?

Prostaglandins.

Where is cholesterol mainly synthesized

Liver

What is the rate-limiting enzyme?

HMG-CoA Reductase

HMG-CoA Reductase converts HMG-CoA into what?

Mevalonate

What are four major functions of cholesterol?

Cell membranes, steroid hormones, vitamin D, bile salts

Which lipoprotein carries dietary fat?

Chylomicrons.

Which lipoprotein transports triglycerides from the liver?

VLDL

Which lipoprotein delivers cholesterol to tissues

LDL

Which lipoprotein returns cholesterol to the liver?

HDL

Why is LDL considered "bad" cholesterol?

It deposits cholesterol in arteries

Why is HDL considered "good" cholesterol?

It removes excess cholesterol from tissues.

Familial Hypercholesterolemia is caused by defects in what?

LDL receptors

What drug class inhibits HMG-CoA Reductase?

Statins