Amino Acid Degradation & Urea Cycle

Question 1

Two Sources of Amino Acids:

Answer 1

• diet
• degradation of defective/unnecessary cellular proteins

Question 2

Two Reasons Proteins May Be Defective:

Answer 2

• errors in translation
• oxidative damage

Question 3

First 2 Priority Use of Amino Acids

Answer 3

• protein synthesis
• nucleotide synthesis

Question 4

If the needs for protein synthesis and nucleotide synthesis have been met, what happens to amino acids?

Answer 4

They are degraded into carbon skeletons for metabolism. The nitrogen is removed from the amino acids and excreted as urea.

Question 5

Are amino acids stored for later use?

Answer 5

No.

Question 6

NH4+

Answer 6

ammonium

Question 7

ammonium

Answer 7

NH4+

Question 8

Describe the Basic Structure of an Amino Acid

Answer 8

An Amino Group (NH3+),
a Carboxyl Group (COO-),
and an R Group all attached to a C
(an alpha-H is also attached to the C)

Question 9

What what does Alanine become when the Amino Group is removed?

Answer 9

pyruvate

Question 10

Amino Group

Answer 10

NH3+

Question 11

Carboxyl Group

Answer 11

COO-

Question 12

What does alpha-ketoglutarate become when an alpha-amino group is added?

Answer 12

glutamate

Question 13

What does Asapartate become when the amino group is removed?

Answer 13

oxaloacetate

Question 14

What is formed from the oxidative deamination of glutamate?

Answer 14

alpha-ketoglutarate

Question 15

What is the excreted form of NH4+ called?

Answer 15

Urea

Question 16

What is the significance of glutamate dehydrogenase?

Answer 16

It assists Nitrogen entry and exit from biochemical systems

Question 17

What does glutamate dehydrogenase use for reducing power?

Answer 17

NADH or NADPH

Question 18

What does ATP and GTP do to glutamate dehydrogenase?

Answer 18

alloseterically inhibits it

Question 19

What does ADP and GDP do to glutamate dehydrogenase?

Answer 19

allosterically activates it

Question 20

When is the oxidation of amino acids the fastest?

Answer 20

when the energy charge in the cell is low

Question 21

The amino groups of which two amino acids can be converted directly into ammonium?

Answer 21

serine
threonine

Question 22

What are the 3 Branched Chain Amino Acids?

Answer 22

Valine
Leucine
Isoleucine

Question 23

Which amino acids can the liver not deaminate?

Answer 23

The branched chain amino acids:
valine, leucine, & isoleucine