Exam 4

Question 1

What protein binds to indogenous proteins through formation of an isopeptide bond?

Answer 1

Ubiquitin

Question 2

Ubiquinated proteins are brought to what multimeric protein for destruction?

Answer 2

Proteasome

Question 3

What is the chemical equation of Aspartate Aminotransferase?

Answer 3

Aspartate + α-Ketoglutarate → Oxaloacetate + Glutamate

Question 4

When the amino acid alanin is deaminated, what alphaketo acid is formed?

Answer 4

Pyruvate

Question 5

What are the 7 major metabolites formed from the carbon skeletons of amino acids during amino acid catabolism?

Answer 5

Pyruvate

Acetyl CoA

Acetoacetyl CoA

α-Ketoglutarate

Succinyl CoA

Fumarate

Oxaloacetate

Question 6

What cofactor that functions in amino acid tranferase reactions to form a protonated Shiff base with the incoming amino acid?

Answer 6

Pyridoxical Phosphate

Question 7

Oxidative Deamination

Answer 7

Enzyme: glutamate dehydrogenase

1. Glutamate is oxidized to form a Shiff-base
2. Amino group is hydrolyzed to yield free ammonium ion and α-Ketoglutarate

Question 8

Explain the glucose-alanine cycle

Answer 8

Branched amino acids are transaminated, with pyruvate as the acceptor to form alanine and carbon skeletons in the muscles. These carbon skeletons can be used as fuel in the muscle. Alanine travels to the liver and transaminated to form pyruvate and the amino group acceptor α-ketoglutarate is converted to glutamate–the amino group can be oxidized to provide nitrogen to urea cycle. Pyruvate can be used to gemerate glucose (gluconeogenesis). Glucose produced by the liver is sent out and can be used by muscles.

Question 9

What are the metabolites that produce carbamoyl phosphate?

Answer 9

2 ATP, CO₂, and Ammonium

Question 10

What intermediate links the TCA and Urea cycles?

Answer 10

Fumarate

Question 11

Protein digestion begins in the…

Answer 11

stomach

Question 12

What zymogen is released in this organ that becomes activated to produce a protease that specifically acts in this environment?

Answer 12

Zymogen: Pepsinogen

Activated Protease: Pepsin

Activated by: Low pH

Question 13

Where is the protease enteropeptidase found?

Answer 13

luminal surfase of enterocytes (lines te surface of the small intestine, faces the interior)

Question 14

Wnteropeptidase activates what zymogen that initiates a protease cascade?

Answer 14

Trypsinogen

Question 15

Where is trypsinogen produced?

Answer 15

Pancreas

Question 16

What is the activated form of trypsinogen?

Answer 16

Trypsin

Question 17

What are the zymogens activated by the protease in 3C?

Answer 17

Proelastase

Chymotrypsinogen

Procarboxypeptidase

Question 18

What is the activated counterpart of Proelastase?

Answer 18

elastase

Question 19

What is the activated counterpart of Chymotrypsinogen?

Answer 19

Chymotrypsin

Question 20

What is the activated counterpart of Procarboxypeptidase?

Answer 20

Carboxypeptidase

Question 21

Dietary oligopeptides are not transported directly into enterocytes. They are hydrolized by which protease found on the luminal surface of enterocytes?

Answer 21

digopeptidase

aminopeptidase

Question 22

What are the essential amino acids?

Answer 22

Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Arginine, Leucine, Lysine

Question 23

Name the 3 branched chain amino acids broken down in muscle for fuel.

Answer 23

Valine

Isoleucine

Leucine

Question 24

What disease is caused by a failure in branched chain catabolism?

Answer 24

Maple Syrup Urine Disease

Question 25

What are the symptoms of maple syrup urine disease?

Answer 25

marked cognitive deficiency and failure to thrive

Question 26

What is the basis for the disease PKU?

Answer 26

Autosomal recessive mutation in the gene encoding phenylalanine hydroxylase

Insufficient concentrations of tetrahydrobiopterin

This results in lack of or reduction in conversio of Phenylalanine to Tyrosine that causes buld up of Phenylalanine and conversion of phenylpyruvate

Question 27

What is the treatment for PKU?

Answer 27

reduction of Phenylalanine in the diet and supplement with Tyrosine

Question 28

If untreated, PKU produces what physiological problems?

Answer 28

marked cognitive deficiency

mousy odor in urine/sweat

albinism

Question 29

What is the basis of Alkaptonuria?

Answer 29

lack of homogentisate oxygenase

Question 30

What is the symptoms of Alkaptonuria?

Answer 30

black urine

Question 31

Which amino acids are ketogenic only?

Answer 31

Leucine

Lycine

Question 32

Which amino acids are both ketogenic and glucogenic?

Answer 32

Phenylalanine

Tryptophan

Isoleucine

Tyrosine

Question 33

What are the main sources of Nitrogen for biologic systems?

Answer 33

Nitrogen fixation from N₂ by bacteria and archea

splitting of N₂ by lightning

industrial sources

Question 34

What are the two major classes of metabolites which require nitrogen for their synthesis?

Answer 34

Amino Acids

Nucleotides

Question 35

What enzyme splits and reduces atmospheric oxygen in bacteria?

Answer 35

Nitrogenase

Question 36

Which enzyme is the prime regulator of nitrogen flow in the cell?

Answer 36

Glutamine Synthetase

Question 37

What is the benefits of a neuron specific isoform of the enzyme in Q15?

Answer 37

reduction in ammonia

regulation of levels of glutamate

Question 38

What is the function of SAM?

Answer 38

a source of activated methyl groups for methyl transfer

Question 39

Build up of homocysteine of methionine synthesis results in…

Answer 39

higher risk for coronary heart disease

Question 40

Which of the following is NOT an amino acid derivative?

Serotonin

Beta-Carotene

Glutathione

Norepinephrine

Answer 40

Beta-Carotene