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biochem 2 ex. 2 > amino acids > Flashcards

amino acids Flashcards

1
Q

what are the 3 metabolic circumstances where we break down AA?

A

Protein turnover- breakdown of cellular proteins
Protein rich diet- surplus
Starvation, fasting, uncontrolled diabetes- carbs unavailable or not properly used

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2
Q

when we have a low energy charge, what happens to an amino acid?

A

it oxidized and generates ATP

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3
Q

when we have low blood glucose what happens to an amino acid?

A

it is converted to enter gluconeogenesis = glucose

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4
Q

when we have high energy charge and lots of glucose what happens to an AA?

A

converted in the liver for fat synthesis = fat

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5
Q

where in the body do we find our small pools of free amino acids?

A

cells
blood
extracellular fluid

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6
Q

pools of free AA are supplied by the breakdown of what?

A

endogenous protein
dietary protein
synthesis of non-essential AA

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7
Q

what is the primary site for amino acid catabolism?

A

liver

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8
Q

after a meal, how much AA come from the portal blood to the liver?

A

50-65%

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9
Q

50% of the ATP production in the liver comes from?

A

AA oxidation

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10
Q

what are the 6 amino acids that skeletal muscle can oxidize?

A

LIV GAA

Leucine 
Isoleucine
Valine 
Glutamate
Aspartate 
Asparagine
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11
Q

once we remove the amino group from the amino acid, what is leftover?

A

a-ketoacid

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12
Q

what AA are transferred from the extra hepatic tissues to the liver?

A

glutamine

alanine

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13
Q

a-ketoacids are also know as?

A

carbon skeleton

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14
Q

when we remove an amino group, a-ketoacid is leftover. What happens to the a-ketoacid/carbon skeleton?

A

it is able to enter metabolic pathways

krebs, GNG, fat synthesis etc

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15
Q

transamination is the transfer of an amino group. What enzyme and coenzyme is needed?

A

aminotransferase and pyroxidal phosphate (B6 derivative)

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16
Q

deamination is the removal of an amino group. what enzymes are needed?

A

lyases

dehydratases or dehydrogenases

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17
Q

transfer of an amino group from one amino acid to an a-keto acid is called?

A

transamination

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18
Q

removal of an amino group from an amino acid is called?

A

deamination

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19
Q

transamination occurs in many tissues, most amino acids transfer their amino group to?

A

a-ketoglutarate

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20
Q

the transfer to a-ketoglutarate results in?

A

glutamate and a-ketoacid

-this is reversible

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21
Q

removal of amino group as free ammonia is called?

A

oxidative deamination

22
Q

oxidative deamination of glutamate in the liver provides what?

A

amino group for excretion (urea cycle)

23
Q

glutamate into free ammonia needs what enzyme?

A

glutamate dehydrogenase

oxidative deamination

24
Q

what are the 4 amino acids in nitrogen metabolism that can easily convert to Krebs intermediates?

A

Glutamate- a-ketoglutarate
Glutamine- a-ketoglutarate
Alanine- pyruvate
Aspartate- oxaloacetate

25
what 2 amino acids collect and deliver amino groups?
glutamine | glutamate
26
in the liver, AA transfer their NH2 to a-ketoglutarate to form?
glutamate
27
in the liver, glutamate can enter mitochondria to release amino group and do what?
form NH4+ or donate the amino group to another carbon skeleton
28
amino groups are collected in the liver as?
glutamate
29
what is one job of glutamate?
to provide amino group to urea cycle for excretion
30
where is glutamate transported?
from cytosol to mitochondria
31
ammonia generated in extrahepatic tissues is converted to?
glutamine
32
what 2 amino acids make up the highest concentration of AA in the liver?
glutamine | glutamate
33
free ammonia is combined with glutamate to form?
glutamine
34
what enzyme is needed to convert glutamate into glutamine?
glutamine synthetase
35
muscle is responsible for giving other tissue nitrogen to build what?
amino acids and nitrogenous bases and nucleotides (new cells)
36
how does muscle give other tissues nitrogen?
it steals nitrogen from other AAs and creates glutamine for export
37
which AAs will be the donors of nitrogen to make glutamine?
LIV GAA ``` leucine isoleucine valine glutamate aspartate asparagine ```
38
what is the job of glutamine synthetase?
add nitrogen to glutamate to make glutamine
39
NH3 comes primarily from?
BCAAs
40
how does glutamine turn back into glutamate?
glutaminase- hydrolyzes glutamine into glutamate
41
when a muscle contracts, it produces _____ and ______ from fast glycolysis
pyruvate and lactate
42
when a muscle contracts, what does protein (AA) breakdown produce?
ammonia
43
describe how a muscle makes alanine
1. amino group from AA breakdown is transferred to a-ketoglutarate to form glutamate 2. glutamate gives the amino group to pyruvate 3. pyruvate makes alanine with ALT (alanine aminotransferase)
44
pyruvate + glutamate -> alanine + a-ketoglutarate which reaction is this known as?
muscle ALT exercising muscle produces pyruvate and pushes the reaction toward alanine
45
alanine + a-ketoglutarate -> pyruvate + glutamate what is this reaction known as?
liver ALT lots of alanine arriving from the muscle pushes the reaction toward pyruvate -can be used as substrate for GNG
46
describe the glucose- alanine cycle
1. amino group is transferred from glutamate to pyruvate which makes alanine to be transferred to the liver 2. once in the liver, the alanine is converted back into pyruvate to be used for GNG 3. glucose is then transported back to the muscle to be used during exercise
47
how is aspartate made?
amino group is transferred from glutamate to oxaloacetate to form aspartate glutamate + oxaloacetate -> a-ketoglutarate + aspartate
48
what enzyme is needed to convert glutamate into aspartate?
AST- aspartate aminotransferase
49
where is aspartate more commonly found?
in the heart, but some in the liver as well
50
what are the 3 main uses for aspartate?
donating nitrogen for purine/pyrimidine synthesis donating nitrogen for the urea cycle used for transporting across the mitochondrial membrane

biochem 2 ex. 2 (8 decks)

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