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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
Q

what 2 amino acids collect and deliver amino groups?

A

glutamine

glutamate

26
Q

in the liver, AA transfer their NH2 to a-ketoglutarate to form?

A

glutamate

27
Q

in the liver, glutamate can enter mitochondria to release amino group and do what?

A

form NH4+ or donate the amino group to another carbon skeleton

28
Q

amino groups are collected in the liver as?

A

glutamate

29
Q

what is one job of glutamate?

A

to provide amino group to urea cycle for excretion

30
Q

where is glutamate transported?

A

from cytosol to mitochondria

31
Q

ammonia generated in extrahepatic tissues is converted to?

A

glutamine

32
Q

what 2 amino acids make up the highest concentration of AA in the liver?

A

glutamine

glutamate

33
Q

free ammonia is combined with glutamate to form?

A

glutamine

34
Q

what enzyme is needed to convert glutamate into glutamine?

A

glutamine synthetase

35
Q

muscle is responsible for giving other tissue nitrogen to build what?

A

amino acids and nitrogenous bases and nucleotides (new cells)

36
Q

how does muscle give other tissues nitrogen?

A

it steals nitrogen from other AAs and creates glutamine for export

37
Q

which AAs will be the donors of nitrogen to make glutamine?

A

LIV GAA

leucine
isoleucine 
valine 
glutamate
aspartate
asparagine
38
Q

what is the job of glutamine synthetase?

A

add nitrogen to glutamate to make glutamine

39
Q

NH3 comes primarily from?

A

BCAAs

40
Q

how does glutamine turn back into glutamate?

A

glutaminase- hydrolyzes glutamine into glutamate

41
Q

when a muscle contracts, it produces _____ and ______ from fast glycolysis

A

pyruvate and lactate

42
Q

when a muscle contracts, what does protein (AA) breakdown produce?

A

ammonia

43
Q

describe how a muscle makes alanine

A
  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
Q

pyruvate + glutamate -> alanine + a-ketoglutarate

which reaction is this known as?

A

muscle ALT

exercising muscle produces pyruvate and pushes the reaction toward alanine

45
Q

alanine + a-ketoglutarate -> pyruvate + glutamate

what is this reaction known as?

A

liver ALT

lots of alanine arriving from the muscle pushes the reaction toward pyruvate
-can be used as substrate for GNG

46
Q

describe the glucose- alanine cycle

A
  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
Q

how is aspartate made?

A

amino group is transferred from glutamate to oxaloacetate to form aspartate

glutamate + oxaloacetate -> a-ketoglutarate + aspartate

48
Q

what enzyme is needed to convert glutamate into aspartate?

A

AST- aspartate aminotransferase

49
Q

where is aspartate more commonly found?

A

in the heart, but some in the liver as well

50
Q

what are the 3 main uses for aspartate?

A

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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