Week 14

Question 1

What is the role of HCl in protein digestion?

Answer 1

Denatures proteins and activates pepsinogen to pepsin.

Question 2

What is the role of pepsin in protein digestion?

Answer 2

Endopeptidase that breaks proteins into peptides.

Question 3

What pancreatic enzymes digest proteins?

Answer 3

Trypsin, chymotrypsin, elastase, and carboxypeptidases.

Question 4

What pancreatic zymogens are involved in protein digestion?

Answer 4

Trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidase A and B.

Question 5

Role of glutamine in ammonia transport?

Answer 5

Transports ammonia safely from tissues to liver and kidney.

Question 6

Role of alanine in ammonia transport?

Answer 6

Transports ammonia from muscle to liver.

Question 7

What is transamination?

Answer 7

Transfer of amino group from an amino acid to a keto acid.

Question 8

What is deamination?

Answer 8

Removal of amino group as free ammonia (NH₃).

Question 9

What are the most common transaminases?

Answer 9

ALT and AST.

Question 10

What does elevated ALT and AST indicate clinically?

Answer 10

Liver cell damage (e.g., hepatitis, cirrhosis).

Question 11

What is the glucose-alanine cycle?

Answer 11

Cycle where alanine transports nitrogen from muscle to liver and glucose returns to muscle.

Question 12

What is nitrogen balance?

Answer 12

Difference between nitrogen intake and nitrogen excretion.

Question 13

What is positive nitrogen balance?

Answer 13

Intake exceeds loss (growth, pregnancy).

Question 14

What is negative nitrogen balance?

Answer 14

Loss exceeds intake (starvation, illness).

Question 15

Where does the urea cycle occur?

Answer 15

In the liver.

Question 16

Subcellular location of the urea cycle?

Answer 16

First two steps in mitochondria, remaining steps in cytosol.

Question 17

Rate-limiting enzyme of the urea cycle?

Answer 17

Carbamoyl phosphate synthetase I (CPS I).

Question 18

Why is the urea pathway called a cycle?

Answer 18

Ornithine is regenerated and reused.

Question 19

What activates CPS I?

Answer 19

N-acetylglutamate.

Question 20

When does urea cycle activity increase?

Answer 20

High protein intake and starvation.

Question 21

How is ammonia toxic to the brain?

Answer 21

Causes glutamine accumulation, cerebral edema, and ATP depletion.

Question 22

Causes of congenital hyperammonemia?

Answer 22

Urea cycle enzyme deficiencies.

Question 23

Causes of acquired hyperammonemia?

Answer 23

Liver failure, cirrhosis, hepatitis, drugs (e.g., valproate).

Question 24

General features of congenital hyperammonemia?

Answer 24

Vomiting, lethargy, poor feeding, developmental delay, high ammonia.

Question 25

Most common urea cycle disorder?

Answer 25

Ornithine transcarbamylase (OTC) deficiency.

Question 26

Inheritance pattern of OTC deficiency?

Answer 26

X-linked recessive.