Lecture 9 - Pyruvate Metabolism

Question 1

Anaerobic glycolysis produces lactate as the end product of glycolysis. In what two locations of the body does this occur?

Answer 1

1. Skeletal muscle

2. Red blood cells

Question 2

The pyruvate dehydrogenase complex (PDH) links glycolysis to what two processes?

Answer 2

1. TCA cycle

2. Fatty acid synthesis

Question 3

Pyruvate dehydrogenase complex is localized in what part of the cell?

Answer 3

The mitochondrial matrix

Question 4

Pyruvate dehydrogenase complex is subject to regulation by its products. Which two products (of the reaction catalyzed by PDH) inhibit PDH?

Answer 4

1. Acetyl CoA

2. NADH

Question 5

How does PDH kinase act on PDH? What effect does this have?

Answer 5

PDH kinase PHOSPHORYLATES PDH.

This inactivates the PDH enzyme.

Question 6

PDH phosphatase is activated by what two molecules?

Answer 6

1. Insulin

2. Ca2+ in muscle (especially upon contraction)

Question 7

Lactate is a substrate for gluconeogenesis by what organ?

Answer 7

Liver

Question 8

Pyruvate carboxylase is localized in the mitochondrial matrix and catalyzes the reaction from pyruvate –> ________.

Answer 8

oxaloacetate

Question 9

Oxaloacetate is the first intermediate in the pathway of _________.

Answer 9

gluconeogenesis

Question 10

___________ is an allosteric ACTIVATOR of pyruvate carboxylase.

Answer 10

Acetyl CoA

Question 11

Acetyl CoA is an allosteric ________ of pyruvate dehydrogenase.

Answer 11

inhibitor

Question 12

A defect in either of the major pathways of pyruvate utilization - conversion to acetyl-CoA or to oxaloacetate - usually leads to an accumulation of what two substrates?

Answer 12

1. Lactate

2. Alanine

Question 13

______ is a deficiency in thiamine because polished rice is consumed instead of unpolished rice.

Answer 13

Beri beri

Question 14

____________ converts pyruvate to Acetyl-CoA.

A. Lactate dehydrogenase
B. Alanine aminotransferase
C. Pyruvate dehydrogenase complex
D. Pyruvate carboxylase

Answer 14

C - this occurs in the mitochondrial matrix

Question 15

________ converts pyruvate to oxaloacetate.

A. Lactate dehydrogenase
B. Alanine aminotransferase
C. Pyruvate dehydrogenase complex
D. Pyruvate carboxylase

Answer 15

D - this occurs in the mitochondrial matrix

Question 16

Acetyl CoA is an allosteric activator of ____________.

A. Lactate dehydrogenase
B. Alanine aminotransferase
C. Pyruvate dehydrogenase complex
D. Pyruvate carboxylase

Answer 16

D

Question 17

Acetyl CoA is an allosteric inhibitor of _____________.

A. Lactate dehydrogenase
B. Alanine aminotransferase
C. Pyruvate dehydrogenase complex
D. Pyruvate carboxylase

Answer 17

C

Question 18

In the fed state in the liver, pyruvate (from glucose) is converted to ________, which drives both the TCA cycle and FA synthesis.

Answer 18

acetyl CoA.

Question 19

In the fasted state in the liver, pyruvate will be converted to ____________ to run gluconeogenesis.

Answer 19

Oxaloacetate

Question 20

In the fed state in the skeletal muscle, pyruvate will be channeled into the _________ to make energy.

Answer 20

TCA cycle

Question 21

In the fasted state in the skeletal muscle, there is not much glucose to make energy. ______ are converted to acetyl-CoA to make energy via the TCA cycle.

Answer 21

Fatty acids