Amino Acid Metabolism Flashcards

1
Q

Amino Acids

A

small organic compounds with an amino and carbohydrate terminus

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2
Q

Essential Amino Acids

A

mammals can’t make but need must get from diet
His, Ile, Leu, Lys, Met, Phe, Thr, Trp, Val

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3
Q

Nonessential Amino Acids

A

mammals can make
Ala, Asp, Asn, Glu, Ser

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4
Q

Conditionally Essential

A

can make most of what need
may require during illness/certain growth stages
Arg, Cys, Gln, Gly, Pro Tyr

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5
Q

What are the 20 amino acids used in?

A

Protein synthesis

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6
Q

What are the excitatory amino acids?

A

Glutamate and Aspartate

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7
Q

What are the inhibitory amino acids?

A

Glycine and GABA

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8
Q

How any amino acids can bacteria and plants make? What about mammals?

A

bacteria and plants make all 20
mammals can make about half

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9
Q

What is glutamate formed from?

A

alpha-ketoglutarate

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10
Q

Which two reactions does glutamine synthetase facilitate?

A

Phosphorylation and amination

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11
Q

What is glutamine important for?

A

removable of excess nitrogen
donates nitrogen into other biosynthetic pathways

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12
Q

How can mammals interconvert Pro and Arg?

A

the urea cycle and ornithine aminotransferase

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13
Q

How can bacteria make Pro and Arg?

A

directly from glutamate

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14
Q

What is Ser formed from?

A

3-phosphoglycerate from glycolysis
gets oxidized into 3-phosphohydroxypyruvate
a transamination forms phosphoserine
the phosphate is cleaved

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15
Q

The amination of pyruvate forms?

A

Alanine

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16
Q

The amination of oxaloacetate forms?

A

Aspartate

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17
Q

The amination of aspartate forms?

A

Asparagine

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18
Q

What helps in treatment of childhood acute lymphoblastic leukemia, acute, myeloid leukemia, and non-hodgkins lymphoma?

A

Asparaginase

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19
Q

What do malignant lymphocytes all require?

A

Serum Asn

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20
Q

Treatment of patients with Asparaginase in combo with other chemotherapy results in about what percentage of remission rates?

A

95%

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21
Q

What amino acids are derived from shikimate found in bacteria and plants?

A

aromatic amino acids

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22
Q

What two pathways does aromatic acid formation use?

A

glycolysis and pentose phosphate pathway

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23
Q

What is Histidine’s pathway similar to?

A

purine biosynthesis

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24
Q

What is histidine being studied as a drug target for?

A

tuberculosis, no approved drugs yet

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25
Q

What does GABA come from?

A

Glu

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26
Q

What does serotonin come from?

A

Trp

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27
Q

What does dopamine come from?

A

Phe or Tyr

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28
Q

What does Epinephrine/norepinephrine come from

A

Phe or Tyr

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29
Q

What does histamine come from?

A

His

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30
Q

What are the 3 possible states of amino acid degradation?

A

normal synthesis and degredation
diet high in protein
starvation/uncontrolled diabetes

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31
Q

Amino acid degradation converts amino acids to?

A

alpha-ketoacids first
then CO2 or water OR taken into gluconeogenesis to make glucose

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32
Q

Amino acid degradation process

A

lose nitrogen first
nitrogen enters the urea cycle/ is used in other pathways
carbon skeleton goes to the citric acid cycle to get broken down
breakdown products can be totally oxidized or used as intermediates

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33
Q

How much energy (percentage) comes from the amino acid degradation in the citric acid cycle?

A

10%

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34
Q

Acetyl Coa converts to acetoacetyl-CoA which breaks down what?

A

ketone bodies

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35
Q

Strictly ketogenic amino acids

A

Leu and Lys

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36
Q

Mixed Amino Acids

A

Phe
Tyr
Trp
Ile
Thr

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37
Q

Strictly Gluconeogenic

A

Asp and Asn
Glu, Gln, Arg, His, Pro
Met and Val
Ala, Cys, Gly, Ser

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38
Q

Where do Leu and Lys enter in the citric acid cycle?

A

Acetoacetyl-CoA or Acetyl-CoA

39
Q

Where do Asp and Asn enter the citric acid cycle?

A

oxaloacetate

40
Q

Where does Glu, Gln, Arg, His, Pro enter the citric acid cycle?

A

Glutamate ->alpha-ketoglutarate

41
Q

Where does Met and Val enter the citric acid cycle?

A

Succinyl-CoA

42
Q

Where does Ala, Cys, Gly, and Ser enter the citric acid cycle?

A

Pyruvate ->oxaloacetate

43
Q

Starting from Acetyl-CoA how much energy is produced by the citric acid cycle?

A

10 ATP

44
Q

Starting from alpha-ketoglutarate, how much energy is produced by the citric acid cycle?

A

7.5 ATP

45
Q

Starting from Succinyl CoA, how much energy is produced by the citric acid cycle?

A

5 ATP

46
Q

Starting from Fumarate, how much energy is produces by the citric acid cycle?

A

2.5 ATP

47
Q

Starting from pyruvate or oxaloacetate, how much energy is produced by the citric acid cycle?

A

0 ATP
these are the entry points into gluconeogenesis

48
Q

Starting from pyruvate how much does it cost to make glyceraldehyde-3-phosphate?

A

cost 5.5 ATP

49
Q

Starting from oxaloacetate how much does it cost to make glyceraldehyde-3-phosphate?

A

4.5 ATP

50
Q

Starting from phosphoenolpyruvate, how much does it cost to make glyceraldehyde-3-phosphate?

A

3.5 ATP

51
Q

Which entry points of the citric acid cycle provide energy?

A

Alpha-ketoglutarate (3 ATP gain)
Succinyl-CoA (0.5 ATP gain)

52
Q

Which entry points into glycolysis result in energy loss?

A

Fumarate (-2 ATP loss)
Oxaloacetate (-4.5 ATP loss)
Pyruvate (-5.5 ATP loss)

53
Q

If it costs energy why would we run gluconeogenesis?

A

2 pyruvate to make glucose
we get 7 ATP from glucose

54
Q

Where are branched chain amino acids broken down?

A

brain and muscle

55
Q

What are branched chain amino acids converted to in order to be used for energy?

A

AcylCoA

56
Q

How is amino acid degradation activated?

A

high concentration of branched chain amino acids

57
Q

How is amino acid degradation regulated?

A

phosphorylation of dehydrogenase complex

58
Q

What happens if the dehydrogenase is defective in amino acid degradation?

A

Alpha-ketoacids will build up and are excreted in urine

59
Q

Is nitrogen stable as N2?

A

no

60
Q

Which amino acids play central roles in nitrogen metabolism?

A

Glu, Gln, Asp, Ala

61
Q

Which amino acids collects nitrogen and allows it to be pooled, reused, and recycled?

A

Glu

62
Q

The conversion of alpha-ketoglutarate to Glu takes nitrogen from other amino acids and takes it where?

A

The mitochondria

63
Q

Which amino acid transports excess nitrogen from other organs to the liver?

A

Gln

64
Q

Which amino acid converts from oxaloacetate to allow delivery of nitrogen from the mitochondria into the urea cycle?

A

Asp

65
Q

Which amino acid transports excess nitrogen from the muscle after the amination of pyruvate?

A

Ala

66
Q

What is dietary protein broken down by?

A

peptidases

67
Q

How do peptidases get to the GI without harming the rest of your body?

A

It turns on at the site of action

68
Q

Where do the amino acids travel to from the GI for further metabolism?

A

the liver

69
Q

Pyridoxal phosphate

A

responsible for transferring the amino group from amino acids on to alpha-ketoglutarate

allows nitrogen to flow through a single point for efficiency and control

70
Q

What is a Schiff base?

A

is an aldimine functional group
formed by the reaction between a primary amine and a carbonyl

71
Q

Nitrogen Excretion process

A
  1. Glu brings excess nitrogen to the liver
  2. Glutamate dehydrogenase removes Glu
  3. Alpha-ketoglutarate can then be recycled and used by the cells
72
Q

If a tissue makes ammonia which amino acid transports it?

A

Gln

73
Q

Gln is a xxx source in other biosynthetic pathways

A

nitrogen

74
Q

Ala transports ammonia from muscle to the?

A

liver to not use gluconeogenesis in the muscle

75
Q

How much ammonia do all plants recycle?

A

nearly all

76
Q

Aquatic animals can excrete ammonia directly into?

A

water

77
Q

Reptiles and birds excrete ammonia as

A

uric acid

78
Q

Land animals excrete ammonia as ?

A

urea

79
Q

Where does urea synthesis occur?

A

in the liver, across the mitochondria and cytosol

80
Q

Free nitrogen is what to cells?

A

toxic

81
Q

Urea Cycle

A
  1. forms carbanoyl phosphate from CO2, ammonia and ATP
  2. Pass carbomoyl phosphate on to ornithine to make citrulline
  3. citrulline passed to the cytosol and adenylation occurs
  4. Asp forms arginosuccinate
  5. breakdown into fumarate and arginine; cleaves to form urea and ornithine
82
Q

The urea cycle is energetically expensive because it costs?

A

3 ATP

83
Q

What happens to the energy cost when the urea cycle is connected to other cycles?

A

decreases

84
Q

The fumarate produced from the urea cycle can enter where?

A

the citric acid cycle

85
Q

A high protein diet or starvation leads to ?

A

breakdown and use of amino acid for fuel

86
Q

What are the two regulation points of the urea cycle?

A

N-Acetyl glutamate
- incr carbamoyl-phosphate synthesis
- incr with increasing [Arg]

Feedback regulation

87
Q

Defects in the urea cycle lead to?

A

ammonia buildup which is toxic

88
Q

What are ways to get rid of ammonia?

A

Ammonul
-mix of sodium benzoate and sodium phenyl acetate

React with and remove glycine and glutamine

89
Q

Can carbs be converted to fats?

A

Yes
glucose -> pyruvate -> AcetylCoa -> Fatty Acid

90
Q

Can carbs be converted to protein?

A

Yes
glucose -> citric acid cycle intermediates -> amino acid -> protein

91
Q

Can protein be converted to fat?

A

Amino Acid -> AcetylCoA -> Fatty Acid

ketogenic amino acids

92
Q

Can proteins be converted to carbs?

A

Amino acid -> citric acid cycle -> glucose
glucogenic amino acids

93
Q

Can fats be converted to proteins?

A

no

94
Q

Can fats be converted to carbs?

A

no