Amino Acid Metabolism

Question 1

Nitrogen cycle

Answer 1

Question 2

Nitrifying bacteria

Answer 2

oxidize NH₄⁺ to NO₃ provides energy for these microbes

Question 3

Denitrifying bacteria

Answer 3

use NO₂ as electron accepts instead of O₂

Question 4

Nitrogen fixing bacteria

Answer 4

reduce N₂ to NH₄⁺ as part of symbiosis with plants

Question 5

Reactions that assimilate NH₃⁺

Answer 5

Carbamoyl-phosphate synthetase I

Glutamate dehydrogenase

Glutamine synthetase

Question 6

Carbamoyl-phosphate synthetase I

Answer 6

Ammonium is converted to carbamoyl-phosphate using 2 ATPs

2 versions of enzyme, one in cytosol and one in mitochondria

Question 7

Glutamate dehydrogenase

Answer 7

Reductive amination of alpha-ketoglutarate to form glutamate

Question 8

Glutamine sythetase

Answer 8

ATP-dependent

Amidation of gamma-carboxyl of glutamate to glutamine

Question 9

Principle route to glutamine

Answer 9

GDH/GS in organisms rich in N

Question 10

Secondary route to glutamine

Answer 10

GS/GOGAT in organisms confronting N limitation

Question 11

Glutamine Synthetase (GS)

Answer 11

Glutamine is the key nitrogen donor

2 step reaction

Highly regulated

Question 12

GS regulation

Answer 12

cumulative feedback

covalent modification

adenylyl transferase

PII (regulated by uridylyl transferase)

Question 13

Alpha-ketoglutarate family amino acids

Answer 13

glutamate

glutamine

proline

arginine

lysine

Question 14

Aspartate family amino acids

Answer 14

aspartate

asparagine

methionine

threonine

isoleucine

lysine

Question 15

Pyruvate family amino acids

Answer 15

alanine

valine

leucine

Question 16

3-phosphoglycerate family amino acids

Answer 16

serine

glycine

cysteine

Question 17

Phosphoenolpyruvate and erythrose-4-phosphate family amino acids

Answer 17

phenylalanine

tyrosine

tryptophan

Question 18

Essential amino acids

Answer 18

arginine

histidine

isoleucine

leucine

lysine

methionine

phenylalanine

threonine

trytophan

valine

Question 19

Non-essential amino acids

Answer 19

alanine

asparagine

aspartate

cysteine

glutamate

glutamine

glycine

proline

serine

tyrosine

Question 20

Carbamoyl phosphate synthase I

Answer 20

1st committed step of urea cycle

2 ATP required

Question 21

Ornithine

Answer 21

precursor to arginine

intermediate in urea cycle

intermediate in arginine degradation

Question 22

Aspartate family- aspartate formation

Answer 22

formed from oxaloacetate by transfer of NH₃ from glutamate

Question 23

Aspartate family- asparagine formation

Answer 23

formed by amidation of beta-carboxyl of aspartate

requires ATP adenylation reaction

Question 24

Pyruvate and 3-phosphoglycerate families- alanine formation

Answer 24

made directly from pyruvate

precursor for valine and leucine

Question 25

Pyruvate and 3-phosphoglycerate families- serine formation

Answer 25

E-PGA to serine one ox to make alpha-keto acrid, transamidation, cleave off PO₄

Question 26

Pyruvate and 3-phosphoglycerate families- glycine formation

Answer 26

made from serine by donating methylene group to tetrahydrofolate

Question 27

Pyruvate and 3-phosphoglycerate familes- cysteine formation

Answer 27

made from homocysteine and serine

Question 28

Ketogenic amino acids

Answer 28

Leucine Lysine Phenylalanine Tyrosine Isoleucine Threonine Tryptophan

Question 29

Amino acids for pyruvate

Answer 29

Ala, Ser, Cys, Gly, Thr, Trp

Question 30

Amino acids for acetoacetate

Answer 30

Leu, Lys, Phe, Tyr

Question 31

Amino acids for acetyl-CoA

Answer 31

Ile, Leu, Thr, Trp

Question 32

Amino acids for alpha-ketoglutarate

Answer 32

Arg, Glu, Gln, Pro, His

Question 33

Amino acids for succinyl-CoA

Answer 33

Ile, Met, Val

Question 34

Amino acids for fumarate

Answer 34

Asp, Phe, Tyr

Question 35

Amino acids for oxaloacetate

Answer 35

Asp, Arg

Question 36

Phenylketonuria

Answer 36

Enzyme- phenylalanine hydroxylase (absence) Result- mental retardation

Question 37

Alkaptonuria

Answer 37

Enzyme- homogenistic acid oxidase (lack) Result- brown/black urine, excrete large amounts of homogenistate