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NPLEX I > Biochemistry- Amino Acids and Proteins > Flashcards

Biochemistry- Amino Acids and Proteins Flashcards

1
Q

Tryptophan is a precursor for what neurotransmitter?

A

serotonin

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2
Q

The reaction of tryptophan to serotonin requires what vitamin as a cofactor?

A

B6- pyrodoxine

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3
Q

Tryptophan can also be turned into what molecule?

A

Niacin

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4
Q

Phenylkeonturia is a genetic inability (lack of phenylalanine hydroxylase) to convert phenylalanine into what aminoacid?

A

Tyrosine

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5
Q

Tyrosine is the precursor for which 2 neurotransmitters and what is the intermediate substance produced?

A

Norepi, and Epinephrine

Dopamine intermediate

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6
Q

What is the rate-limiting enzyme for the production of L-DOPA (and therefore catecholamines in general) from tyrosine?

A

Tyrosine hydroxylase

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7
Q

What inhibits and promotes the activity of tyrosine hydroxylase?

A

Promotes: cold, stress
Inhibits: Norepi

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8
Q

What vitamin is needed as a cofactor for the production of Norepi from dopamine?

A

Vitamin C

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9
Q

What is the name of the enzyme that breakdown Norepi and epinephrine?

A

Monoamineoxidase (MAO)

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10
Q

What is the breakdown product of MAOs action of norepi and epic?

A

vanillmandelic acid (VMA)

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11
Q

What are the 3 branched chain amino acids?

A

BCAAs: valine, isoleucine, leucine

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12
Q

Post-translational modification of proline and lycine to form hydroxylycine and hydroxyproline in collagen formation requires what vitamin?

A

Vitamin C

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13
Q

Which are the only 3 amino acids that can be posttranvslationally modified by phosphorylation?

A

serine, threonine, tyrosine

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14
Q

Acetylcholine is formed from what amino acid?

A

Serine

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15
Q

GABA (gamma amino butyric acid) is formed from what amino acid?

A

Glutamate/ Glutamic acid

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16
Q

The reaction of glutamic acid to GABA requires what vitamin as a cofactor?

A

B6 (pyrodoxine)

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17
Q

Histamine is formed from what amino acid?

A

Histadine

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18
Q

Which amino acid is the main methyl donor in the body?

A

Methionine

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19
Q

What are the 6 amino acids that can be catabolized by skeletal muscle?

A 
Valine
Leucine
Isoleucine
Aspartic acid
Asparagine
Glutamin Acid
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20
Q

What are the 3 amino acids that make up the tripeptide glutathione?

A

Cysteine, Glycine and glutamic acid

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21
Q

What are the 2 initial precursors for heme synthesis?

A

Glycine and succinyl CoA

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22
Q

What amino acid is the main transporter of nitrogen (ammonia) in the blood?

A

Glutamine

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23
Q

Alanine can be converted into what substance?

A

Pyruvate

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24
Q

What amino acid is a major component of actin and myosin? What form does it take?

A

Histadine in the form of 3-methyl histadine

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25
What type of bond holds together the amino sequence of peptides?
covalent
26
what are the only 2 sulphur containing amino acids?
cysteine, methionine
27
What 2 bonds hold a secondary protein structure?
disulfide, weak covalent bonds
28
3D folding is seen is which level of protein structure?
tertiary
29
2 or more single polypeptide chains bonded by weak bonds is called what?
quaternary structure
30
Heme molecule is an example of what type of protein structure?
quaternary
31
2 cysteine resides can form what type of bond
disulfide
32
a water soluble protein is known as what?
globular, hydrophilic
33
What kinds of bonds make up secondary structure?
salt bridges, hydrophobic interactions, hydrogen bonds...
34
Atoms that share 1 or more electrons are bonded by what type of bond?
covalent
35
What are the 9 essential amino acids?
Threonine, Valine, Tryptophan, Phenylalanine, Isoleucine, Methionine, Histadine, Alanine, Leucine, Lysine (PVT TIM HALL)
36
The removal of an alpha amino group from an amino acid is the first stage in amino acid catabolism and is known as what?
Transamination
37
Catabolism of amino acids uses what 2 types of reaction?
oxidative deamination, transamination
38
The effect of transamination reactions is to collect the amino groups from all the other amino acids in the form of only on amino acid- which one?
glutamate
39
Transaminases require what vitamin as a cofactor?
B6 (pyrodoxine)
40
Alph ketoglutarate in the alphketo acid for what amino acid?
glutamate
41
Oxaloacetate is the alphaketo acid for what amino acid?
aspartate
42
Pyruvate is the alphketo acid for what amino acid?
Alanine
43
Conversion of an amino acid into its alphaketo acid with the release of ammonia is what type of reaction?
oxidative deamination
44
Where does oxidative deamination occur?
in the liver and kidneys
45
In what part of the cell does oxidative deamination occur?
mitochondria
46
What is the main amino acid to undergo oxidative deamination?
glutamate
47
What is the main enzyme in oxidative deamination?
glutamine dehydrogenase
48
Which amino acid is present in the blood in the highest levels?
Glutamine- it is the major carrier of amino groups so toxic nitrogen can be carried in a non-toxic form from extra hepatic tissues to the liver
49
Glutamine synthetase is the enzyme that catalyzes the reaction of glutamate into glutamine. It's levels are especially high in which tissues? Why?
brain- it's especially sensitive to ammonia
50
Which amino acid transfers ammonia from the muscle to the liver?
alanine
51
Urea is formed from what 2 molecules?
CO2 and ammonia
52
Where does the urea cycle take place?
liver
53
How is the urea cycle regulated?
substrate availability ie- dietary protein
54
Where do the 2 nitrogen atoms in urea come from?
ammonia, aspartate
55
Which Krebs cycle intermediate is produced by the urea cycle?
fumarate
56
what are the 4 major constituents of urine?
urea, ammonia, creatinine, uric acid
57
What is the role of HCl in protein digestion?
denatures the protein and provides optimal pH for pepsinogen conversion to active pepsin
58
What enzyme has optimum activity at pH2?
pepsinogen/pepsin
59
What 3 aromatic amino acids have their peptide bonds hydrolyzed by pepsin?
Tyrosine, phenylalanine, tryptophan
60
Enterokinase is the enzyme that activates which zymogen released by the pancreas?
trypsinogen
61
Which enzyme activates all other enzymes released by the pancreas?
trypsin
62
What is the overall fate of proteins that we eat?
form free amino acids and enter the liver via the portal blood system
63
What is the role of brush border enzymes in protein digestion?
break down smaller peptides to release free amino acids that a readily absorbed
64
Which bonds need to be broken for a peptide to become denatured?
weak and disulfide bonds (secondary structure)

NPLEX I (22 decks)

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