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Biochemistry I > Chapter 31: Amino Acid Biosynthesis > Flashcards

Chapter 31: Amino Acid Biosynthesis Flashcards

1
Q

Essential amino acids

A

-

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2
Q

Non-essential amino acids

A

-

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3
Q

Root nodule of the pea plant protects

A
  • The nitrogenase enzyme form degradation by oxygen
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4
Q

There is an obligate requirement for nitrogen to

A
  • Synthesize mino acids
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5
Q

Nitrogen, nitrites, and nitrates are used by bacteria and plants, then

A
  • We assimilate them into our diet
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6
Q

The liver is the major organ responsible for

A
  • Nitrogen metabolism

- Amino acid biosynthesis

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7
Q

Amino acids synthesized in the liver

A
  • Glutamate
  • Glutamine
  • Alanine
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8
Q

The most significant reactions in the pathways of amino acids are

A
  • Glutamate dehydrogenase (reversible)
  • Transamination reactions
  • One-carbon transfers
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9
Q

Glutamate dehydrogenase

A
  • Mitochondrial enzyme

- NH3 donated to alpha-ketoglutarate (forms AA glutamate at high livels of NH3)

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10
Q

One-carbon transfers are mediated by either

A
  • Tetrahydrofolate

- S-adenosylmethionine

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11
Q

One 10 of the amino acids required are synthesized

A
  • de novo (non-essential amino acids)
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12
Q

Non-essential amino acids are made

A
  • By the body
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13
Q

Biosynthesis achieved by

A
  • Simple reaction sequences
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14
Q

Essential amino acids must be provided

A
  • In the diet
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15
Q

In infants (+ve N balance) with high urea cycle activity,

A
  • Arginine becomes essential in the diet
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16
Q

Tyrosine is really misclassified since its made from

A
  • The essential amino acid phenylalanine
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17
Q

Although mammals synthesize arginine,

A
  • They cleave most of it to form urea
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18
Q

Phenylalanine hydroxase

A
  • Allows us to convert tyrosine to phenylalanine
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19
Q

Amino acids can also be made with a wide range of

A
  • Synthetic pathways

- 6 basic groups

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20
Q

Oxaloacetate (also in CAC and gluconeogenesis) can be used to make

A
  • Aspartate

- Aspartate can then make arginine, methionine, threonine (then isoleucine), lysine

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21
Q

Pyruvate can be used to make

A
  • Alanine
  • Valine
  • Leucine
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22
Q

Riobse-5-phopshate can by synthetically converted to

A
  • Histidine
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23
Q

3-phosphoglycerate can be used to make

A
  • Serine (AA)

- Serine can then make cysteine and glycine

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24
Q

Pyruvate (also in …) can be used to make

A
  • Alanine
  • Valine
  • Leucine
25
Q

Riobse-5-phopshate (also in …) can by synthetically converted to

A
  • Histidine
26
Q

3-phosphoglycerate (also in …) can be used to make

A
  • Serine (AA)

- Serine can then make cysteine and glycine

27
Q

Alpha-ketoglutarate (also in …) can be used to make

A
  • Glutamate

- Glutamate can then make glutamine, proline, arginine

28
Q

Phosphoenolpyruvate (also in …) + Erythrose-4-phosphate (also in …) can be used to make

A
  • Phenylalanine (then tyrosine)
  • Tyrosine
  • Tryptophan
29
Q

Cysteine is formed from

A
  • Carbons from serine

- Sulfur from methionene

30
Q

Glysine is formed from

A
  • Serine by a serine hydroxymethyl transferase
31
Q

Reversible transfer of the side chain carbon atom of serine to tetrahydrofolate forms

A

-glycine

Glycine is a pyridoxical phpsphate

32
Q

Alanine is formed by

A
  • Transamination of pyruvate

- Made from pyruvate in a single step

33
Q

Alanine is the 2nd most abundant

A
  • Amino acid in circulation

- (Number 1 is glutamine)

34
Q

Alanine is important in the glucose-alanine cycle because it links

A
  • Carbohydrate and amino acid metabolism
35
Q

Alanine transaminase (ALT) serum levels are measured to

A
  • Evaluate liver function
36
Q

Alanine is a common substrate for gluconeogenesis by

A
  • Reversal of this alanine formation via transamination of pyruvate reaction
37
Q

Alanine transaminase (ALT) requires

A
  • Pyridoxical cofactor
38
Q

Alanine transaminase (ALT) requires

A
  • Pyridoxical cofactor
39
Q

Aspartate transaminas (AST) catalyzes

A
  • Transamination of oxaloacetate to form aspartate

- Requires pyridoxical phopshate as a cofactor

40
Q

Glutamate (alpha-ketoglutarate) participates in the aspartate transaminase reaction as the

A
  • Amino group donor
41
Q

Serum levels of AST are also utilized in

A
  • Clinical evaluation of liver function
42
Q

The amidation of aspartate is catalyzed by

A
  • Asparagine synthetase

- Requires ATP

43
Q

Nitrogen donor of aspartate amidation reaction

A
  • Glutamine in eukaryotes

- Ammonium in bacteria

44
Q

Glutamate dehydrogenase forms

A
  • Glutamate from alpha ketoglutarate
  • Reductive amination
  • Reversible reaction
45
Q

Hydroxyproline is formed from

A
  • Proline catalyzed by a hydroxylase
  • Requires molecular O2 and vitamin C
  • Can be post-translationally modified
  • Involved with collagen
46
Q

Tyrosine (nonessential) is produced by

A
  • Hydroxylation of phenylalanine (essential - from diet)
47
Q

Tyrosine is not usually considered to be an essential amino acid when

A
  • Phenylalanine is present in diet
48
Q

Synthesized form ingested phenylalanine that is converted to tyrosine by

A
  • Phenylalaine hydroxylase
49
Q

Impossible to synthesize phenylalanine

A
  • In the reverse direction
50
Q

In PKU, a deficiency of the enzyme leads to

A
  • Elevated phenylalanine levels in the blood

- Accumulation of

51
Q

In the case of PKU, infants can be placed on

A
  • Special diet
  • Infants can alter diet again at 3-4 years of age and live a regular life
  • Diagnosis must be made early
52
Q

Phenylalanine is found in

A
  • Aspartame

- Found in many artificial sweeteners

53
Q

Interconversion of C1 units carried by

A
  • Tetrahydrofolate in amino acid metabolism
54
Q

Methyl-derivative is used to make

A
  • Methionine (methionine synthase) is the most reduced
55
Q

With vitamin B12 deficiency,

A
  • Most THF is trapped in the methyl-derivative/form

- Manifests in pernicious anemia

56
Q

Formyl derivative of THF is the most

A
  • Oxidized form
57
Q

When trapped in the methyl-form, there is a requirement for

A
  • Vitamin B12

- Absorbtion requires intrinsic factor that is coming from parietal cells

58
Q

In the absence of vitamin B12

A
  • Methyl-form of THF cannot be removed or reused

- Causes circulation problems

Biochemistry I (34 decks)

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