Amino Acids

Question 1

Tryptophan

Answer 1

Aromatic

Question 2

Leucine

Answer 2

Branched

Question 3

Isoleucine

Answer 3

Branched

Question 4

Which two amino acids are ketogenic?

Answer 4

Leucine and lysine

Question 5

Which four amino acids are both glucogenic and ketogenic?

Answer 5

Tyrosine, isoleucine, phenylalanine, and tryptophan.

Question 6

What are the two intracellular pathways for protein degradation?

Answer 6

1. Ubiquination and degradation in the proteasome

2. Degradation in lysosomes

Question 7

What are the two nitrogen sources that enter the urea cycle?

Answer 7

Free ammonia from breakdown of an amino acid and from aspartate.

Question 8

Which amino acid produces NO?

Answer 8

Arginine

Question 9

Which AAs contain sulfur?

Answer 9

Cysteine and methionine

Question 10

SAM is a precursor for what?

Answer 10

Homocysteine

Question 11

Which amino acids are aromatic?

Answer 11

Tryptophan, tyrosine, phenylalanine

Question 12

What is the Keq of transamination reactions?

Answer 12

1 - concentration dependent

Question 13

ALT catalyzes which reaction?

Answer 13

Alanine + alphaketoglutarate -> pyruvate + glutamate

Question 14

AST catalyzes which reaction?

Answer 14

Aspartate + alphaketoglutarate -> OAA + glutamate

Question 15

What is PLP’s role in transamination?

Answer 15

Coenzyme to aminotransferases. Holds the N nearby.

Question 16

PLP is a derivative of what?

Answer 16

Vit B6

Question 17

Write out the overall reaction of the urea cycle

Answer 17

3ATP+HCO3+NH4+aspartate -> 2ADP+AMP+2Pi+PPi+fumarate+urea

Question 18

What stimulates glutamate dehydrogenase and what inhibits it?

Answer 18

(+) ADP and GDP

(-) ATP and GTP

Question 19

Write out the overall reaction of the urea cycle

Answer 19

3ATP+HCO3+NH4+aspartate -> 2ADP+AMP+2Pi+PPi+fumarate+urea

Question 20

Which disease is associated with a deficiency in alpha ketoacid dehydrogenase complex?

Answer 20

MSUD

Question 21

Which enzyme decarboxylates branched chain AAs?

Answer 21

alpha ketoacid dehydrogenase complex

Question 22

Which disease is associated with a deficiency in alpha ketoacid dehydrogenase complex?

Answer 22

MSUD

Question 23

Tryptophan metabolism results in the formation of what?

Answer 23

Niacin, serotonin, melotonin

Question 24

Phenylalanine metabolism results in the formation of what?

Answer 24

Tyrosine, L-dopa, dopamine, melanin, NE, and epi

Question 25

Glycine metabolism results in the formation of what?

Answer 25

Porphyrin and heme

Question 26

Glutamate metabolism results in the formation of what?

Answer 26

GABA and glutathione

Question 27

Arginine metabolism results in the formation of what?

Answer 27

NO, creatine phosphate, and urea

Question 28

What can cysteine do?

Answer 28

Form disulfide bridges that change protein conformation

Question 29

How can ammonia be transported to the liver for urea cycle?

Answer 29

Glutamine synthase can convert glutamate to glutamine to be transported to the liver.

Question 30

What does muscle use to transport nitrogen?

Answer 30

Alanine instead of glutamine - due to buildup of pyruvate in muscle which can be converted to alanine with ALT

Question 31

Which amino acid is associated with GSH?

Answer 31

Cysteine

Question 32

SAM is a breakdown product of which AA?

Answer 32

Methionine

Question 33

What are the starting and ending points of purine biosynthesis?

Answer 33

Ribose 5P -> IMP

Question 34

What are the two key steps of purine biosynthesis?

Answer 34

PRPP synthetase and GPPA (glutamine phosphoribosyl pyrophosphate aminotransferase)

Question 35

What are the activators and inhibitors of PRPP synthetase?

Answer 35

(+) Pi | -) purines, AMP, GMP, IMP (end-product inhibition

Question 36

What are the activators and inhibitors of GPPA?

Answer 36

(+) PRPP | (-) AMP, GMP, IMP

Question 37

What are the sources of atoms for purine synthesis?

Answer 37

Glutamine, glycine, aspartate, THF, CO2

Question 38

What are the starting and ending points of pyrimidine synthesis?

Answer 38

2ATP + CO2 + glutamine -> UMP

Question 39

What is the key enzymatic step of pyrimidine synthesis?

Answer 39

CPS II

Question 40

What are the activators and inhibitors of CPS II?

Answer 40

(+) ATP, PRPP | (-) UTP

Question 41

What are the sources of atoms for pyrimidine synthesis?

Answer 41

CO2, glutamine, aspartate, ribose sugar added last

Question 42

What is a major difference between pyrimidine and purine biosynthesis?

Answer 42

In purine synthesis, the base is built onto the sugar. In pyrimidine synthesis, the complete base is added onto the sugar at the end.

Question 43

Which enzyme converts RNA to DNA?

Answer 43

Ribonucleotide reductase

Question 44

What is an inhibitor of ribonucleotide reductase?

Answer 44

dATP

Question 45

On which phosphate form does ribonucleotide reductase act on exclusively?

Answer 45

Di-phosphate form

Question 46

What does thymine break down to?

Answer 46

Succinyl-CoA

Question 47

What does cytosine break down to?

Answer 47

Malonyl-CoA

Question 48

What does uracil break down to?

Answer 48

Acetyl-Coa