Sample/practice exam 2019, questions PDF

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TOPIC 11: METABOLIC REGULATION

Multiple Choice Questions

1.

Cellular isozymes of pyruvate kinase are allosterically inhibited by:

a) b) c) d) e)

high concentrations of AMP high concentrations of ATP low concentrations of citrate low concentrations of acetyl-CoA low concentrations of ATP

2.

The glycogen debranching enzyme catalyses:

a) b) c) d) e)

degradation of (α1-4) linkages in glycogen formation of (α1-4) linkages in glycogen formation of (α1-6) linkages during glycogen synthesis degradation of (α1-6) linkages in glycogen removal of unneeded glucose residues at the ends of branches

3.

Which enzyme is NOT involved in the synthesis of glycogen from glucose?

a) b) c ) d) e)

Glycogen synthase Branching enzyme De b r a n c h i n ge nz y me Phosphoglucomutase UDP-glucose pyrophosphorylase

4.

Enzymes involved in glycogen synthesis (including synthesis of both α1-α4 and α1-α6 linkages) are:

a) b) c) d) e)

Glycogen phosphorylase and UDP-glucose pyrophosphorylase Glycogen synthase and debranching enzyme Glycogen phosphorylase and hexokinase Glycogen phosphorylase and phosphofructokinase-1 UDP-glucose pyrophosphorylase, glycogen synthase and branching enzyme

5.

The enzyme glycogen phosphorylase:

a) b) c) d) e)

catalyses a hydrolytic cleavage of β1-4 bonds catalyses a phosphorolytic cleavage of α1-4 bonds uses glucose 1,6-phosphate as a substrate uses glucose 6-phosphate as a substrate uses glucose as a substrate

6.

Glycogen biosynthesis from glucose 6-phosphate in the liver:

a) b) c) d) e)

occurs by a reversal of the degradative (glycogen phosphorylase) pathway requires the participation of coenzyme A requires the participation of uridine diphosphate glucose (UDPG) requires the participation of FADH2 is an energy yielding reaction

7.

The release of insulin in response to high blood glucose levels activates:

a) b) c) d) e)

Phosphofructokinase 1 (PFK-1) and glycogen synthase Glycogen branching and debranching enzymes Phosphoglucomutase FBPase-1 and glycogen phosphorylase Glucagon

8.

In glycogen, glucose molecules are linked together along a linear chain by:

a) b) c) d) e)

α1-2 bonds α1-4 bonds α1-6 bonds α1-8 bonds α1-10 bonds

9.

Phosphofructokinase 1 (PFK-1) is inhibited by which molecule?

a) b) c) d) e)

ATP ADP AMP AQP AYP

10.

When blood glucose levels increase, the following occurs:

a)

Insulin is released, which triggers activation of glycogen phosphorylase and inactivation of glycogen synthase Glucagon is released, which triggers inhibition of glycogen phosphorylase and activation of glycogen synthase Glucagon is released, which triggers activation of glycogen phosphorylase and inactivation of glycogen synthase Glucagon is released, which triggers activation of glycogen phosphorylase and glycogen synthase Insulin is released, which triggers inhibition of glycogen phosphorylase and activation of glycogen synthase

b) c) d) e)

Long Answer Questions 1) Describe how the glycolytic pathway is regulated, with particular reference to allosteric regulation of the enzyme phosphofructokinase-1. 2) Describe details of the reciprocal regulation of glycogen catabolism and synthesis, in terms of the enzymes glycogen phosphorylase and glycogen synthase....