Chapter 21: Amino Acid Metabolsim

Question 1

How does nutritional deprevation affect rate of protein degradation?

Answer 1

it increases the rate of protein degradation as proteins are broken down for fuel

Question 2

What proteins are in lysosomes that allow them to break down proteins?

Answer 2

cathespins

Question 3

What kinds of muscles do lysosomes break down in order to release proteins during periods of starvation?

Answer 3

muscles that atrophy: like liver and kidneys, but not the ones that don’t atrophy, like brain.

Question 4

What label is assigned to proteins that can be degraded? Where are they sent to?

Answer 4

they are marked with ubiquitin. marked proteins are then sent to proteosome for degradation.

Question 5

T/F ubiquitin labelling requires ATP

Answer 5

true.

Question 6

the ___ converts amino acids’ amino groups into ___

Answer 6

the liver converts amino groups into urea

Question 7

What is transamination?

Answer 7

the transfer of amino acids’ amino groups to an ALPHA KETOacid (usually alpha keto glutarate) to yield the alphaketoacid of the original amino acid and a new amino acid.

Question 8

When amino acids get burned in the muscle, what compound to they get added to? what does this yield?

Answer 8

when the N’s from AA’s get added to pyruvate, which is used to make alanine, which is then sent to the liver.

Question 9

When amino acids get burned in other tissues besides muscle, what are they turned into?

Answer 9

all amino acids are turned into glutamine before they get sent to the liver.

Question 10

Where does deamination of glutamate occur? Why is this necessary?

Answer 10

in the mitochondria of the LIVER ONLY. Deamination is necessary in order for alpha keto glutarate to be regenerated, allowing for further breakdown of amino acids.

Question 11

What molecule must glutamate transfer its amino group to in order to create aspartate?

Answer 11

oxaloacetate

Question 12

what organ is the urea cycle facilitated in?

Answer 12

the liver

Question 13

How is carbamoyl phosphate synthetase allosterically regulated?

Answer 13

via acetyl glutamate, which accumulates when urea cycle is too slow, ACTIVATING Carbamoyl phosphatase to go faster

Question 14

what are glucogenic amino acids

Answer 14

amino acides that are degraded into pyruvate or krebs cycle intermediates (alpha kg, oxa, fumarate) and can MAKE GLUCOSE

Question 15

What are ketogenic amino acids

Answer 15

amino acids that are degraded into acetyl coA or acetoacetate and thus can be converted into FATTY ACIDS or KETONE BODIES.

Question 16

Which amino acid is both glucogenic and ketogenic?

Answer 16

tryptophan.

Question 17

Name the essential amino acids

Answer 17

arginine
histidine
isoleucine
leucine
methionine
phenylalanine
threonine
tryptophan 
valine

Question 18

Examples of glucogenic amino acids

Answer 18

alanine, serine, cysteine

Question 19

examples of ketogenic amino acids

Answer 19

lysine

Question 20

What happens to the carbon skeletons of the degraded amino acids?

Answer 20

form krebs intermediates (glucogenic) or fatty acid/ ketone body intermediates (ketogenic)

Question 21

draw carbomyl phosphate

Answer 21

see notes

Question 22

Draw arginosuccinate

Answer 22

see notes

Question 23

draw urea

Answer 23

see notes

Question 24

draw ornithine

Answer 24

see notes

Question 25

draw citrulline

Answer 25

see notes

Question 26

alternative method to convert glutamate into alphaketoglutarate without oxaloacetate? what enzyme is involved? where does this happen?

Answer 26

glutamate into alphaketoglutarate via glutamate dehydrogenase.this happens in the liver mitochondria

Question 27

How many atps can a liver cell make from the complete catabolism of Alanine? Draw diagram

Answer 27

16atp per alanine. You need two Alanines to make urea though to begin with. see diagram in notes.

Question 28

the reduction of NADP+ to NADPH requires ____

Answer 28

a hydride ion

Question 29

how many ATP equivalents are burned when a cell os undergoing gluconeogenesis

Answer 29

6

Question 30

What is the key regulated step in the catabolism of free fatty acids in the liver?

Answer 30

trying to transport the fatty acids into the mitochondrial matrix using the carnitine transporter.

Question 31

describe the metabolic path that oxaloacetate can be metabolized into Co2 and H2o

Answer 31

oxa –> pyr –> acetyl coA —> Krebs.

Question 32

Where does the oxidative deamination of aspartic acid occur?

Answer 32

no where, only glutamic acid (glutamate) gets oxidatively deaminated. the rest of the amino acids get transaminated to their alpha keto acids, and their nitrogen groups are given to glutmate, which is then deaminated.

Question 33

what is the redox state for the second carbon in dihydroxyacetone phosphate

Answer 33

2

Question 34

why are amino acids burned during the early stages of starvation?

Answer 34

because they contain glucogenic amino acids that can be made into glucose.

Question 35

what does uncoupling of mitochondrial oxidative phosphoyrlation result in?

Answer 35

no atp synthesis, but continued O2 usage.