생화학4주차

Anaplerotic reaction

Reactions that replenish intermediates in the TCA cycle, allowing it to continue functioning while providing intermediates for biosynthetic reactions.

Pyruvate decarboxylase

The first enzyme (E1) of the PDHC that uses coenzyme TPP to remove carbon dioxide from pyruvate.

Wernicke-Korsakoff syndrome

A serious central nervous system disorder caused by vitamin B1 (Thiamine) deficiency, leading to insufficient ATP supply to brain cells.

Lipoic acid

A cofactor for the PDHC E2 enzyme that, when bound by trivalent arsenic, inhibits enzyme activity.

PDH kinase

A regulatory enzyme that inactivates PDHC by phosphorylating it when ATP levels are high.

Glucokinase

An enzyme with low affinity but high maximum reaction velocity, found in liver parenchymal and pancreatic beta cells, responsible for detecting large glucose influx.

Phosphofructokinase-1 (PFK-1)

The rate-limiting enzyme of glycolysis that is inhibited by high ATP and activated by AMP and fructose 2,6-bisphosphate.

NAD+

The coenzyme that must be continuously regenerated through lactate fermentation to prevent glycolysis from stopping under anaerobic conditions.

Calcium ion (Ca2+)

An ion that stimulates PDH phosphatase, activating PDHC during muscle contraction when its concentration rises.

2 ATP / 36 ATP

The final ATP yield from 1 glucose molecule undergoing anaerobic glycolysis versus aerobic respiration.

Succinyl CoA -> Succinate

The reaction step in the TCA cycle where NADH is not generated.

3 NADH, 1 FADH2, 1 GTP

The total coenzyme and energy yield when 1 Acetyl CoA completes a cycle in the TCA.

Oxidative phosphorylation leads to NAD+ depletion and halts the cycle

The most appropriate description of indirect regulation mechanisms in the TCA cycle.

G-protein activation -> Adenylyl cyclase activation -> cAMP generation -> Protein Kinase A activation

The correct sequence of the second messenger system after glucagon binds to the membrane GPCR.

GLUT-4 is not regulated by insulin in the brain and liver

An incorrect statement about glucose transporters; GLUT-4 is actually regulated by insulin.

Yeast reduces pyruvate to lactate during fermentation

An incorrect statement; yeast actually converts pyruvate to ethanol under anaerobic conditions.

Insulin secretion activates PFK-2, promoting glycolysis

A correct explanation of regulatory factors in glycolysis.

Fructose 6-phosphate -> Fructose 1,6-bisphosphate

Not a substrate-level phosphorylation reaction.

PDHC's oxidative decarboxylation of pyruvate

The major reaction that pyruvate undergoes when entering mitochondria under aerobic conditions.

ADP activates Isocitrate dehydrogenase allosterically under low energy conditions

An accurate description of the regulation of Isocitrate dehydrogenase in the TCA cycle.