Biochemistry- Amino Acids and Proteins Flashcards Preview

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Flashcards in Biochemistry- Amino Acids and Proteins Deck (64)
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1
Q

Tryptophan is a precursor for what neurotransmitter?

A

serotonin

2
Q

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

A

B6- pyrodoxine

3
Q

Tryptophan can also be turned into what molecule?

A

Niacin

4
Q

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

A

Tyrosine

5
Q

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

A

Norepi, and Epinephrine

Dopamine intermediate

6
Q

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

A

Tyrosine hydroxylase

7
Q

What inhibits and promotes the activity of tyrosine hydroxylase?

A

Promotes: cold, stress
Inhibits: Norepi

8
Q

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

A

Vitamin C

9
Q

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

A

Monoamineoxidase (MAO)

10
Q

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

A

vanillmandelic acid (VMA)

11
Q

What are the 3 branched chain amino acids?

A

BCAAs: valine, isoleucine, leucine

12
Q

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

A

Vitamin C

13
Q

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

A

serine, threonine, tyrosine

14
Q

Acetylcholine is formed from what amino acid?

A

Serine

15
Q

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

A

Glutamate/ Glutamic acid

16
Q

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

A

B6 (pyrodoxine)

17
Q

Histamine is formed from what amino acid?

A

Histadine

18
Q

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

A

Methionine

19
Q

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

A
Valine
Leucine
Isoleucine
Aspartic acid
Asparagine
Glutamin Acid
20
Q

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

A

Cysteine, Glycine and glutamic acid

21
Q

What are the 2 initial precursors for heme synthesis?

A

Glycine and succinyl CoA

22
Q

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

A

Glutamine

23
Q

Alanine can be converted into what substance?

A

Pyruvate

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

25
Q

What type of bond holds together the amino sequence of peptides?

A

covalent

26
Q

what are the only 2 sulphur containing amino acids?

A

cysteine, methionine

27
Q

What 2 bonds hold a secondary protein structure?

A

disulfide, weak covalent bonds

28
Q

3D folding is seen is which level of protein structure?

A

tertiary

29
Q

2 or more single polypeptide chains bonded by weak bonds is called what?

A

quaternary structure

30
Q

Heme molecule is an example of what type of protein structure?

A

quaternary

31
Q

2 cysteine resides can form what type of bond

A

disulfide

32
Q

a water soluble protein is known as what?

A

globular, hydrophilic

33
Q

What kinds of bonds make up secondary structure?

A

salt bridges, hydrophobic interactions, hydrogen bonds…

34
Q

Atoms that share 1 or more electrons are bonded by what type of bond?

A

covalent

35
Q

What are the 9 essential amino acids?

A

Threonine, Valine, Tryptophan, Phenylalanine, Isoleucine, Methionine, Histadine, Alanine, Leucine, Lysine
(PVT TIM HALL)

36
Q

The removal of an alpha amino group from an amino acid is the first stage in amino acid catabolism and is known as what?

A

Transamination

37
Q

Catabolism of amino acids uses what 2 types of reaction?

A

oxidative deamination, transamination

38
Q

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?

A

glutamate

39
Q

Transaminases require what vitamin as a cofactor?

A

B6 (pyrodoxine)

40
Q

Alph ketoglutarate in the alphketo acid for what amino acid?

A

glutamate

41
Q

Oxaloacetate is the alphaketo acid for what amino acid?

A

aspartate

42
Q

Pyruvate is the alphketo acid for what amino acid?

A

Alanine

43
Q

Conversion of an amino acid into its alphaketo acid with the release of ammonia is what type of reaction?

A

oxidative deamination

44
Q

Where does oxidative deamination occur?

A

in the liver and kidneys

45
Q

In what part of the cell does oxidative deamination occur?

A

mitochondria

46
Q

What is the main amino acid to undergo oxidative deamination?

A

glutamate

47
Q

What is the main enzyme in oxidative deamination?

A

glutamine dehydrogenase

48
Q

Which amino acid is present in the blood in the highest levels?

A

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
Q

Glutamine synthetase is the enzyme that catalyzes the reaction of glutamate into glutamine. It’s levels are especially high in which tissues? Why?

A

brain- it’s especially sensitive to ammonia

50
Q

Which amino acid transfers ammonia from the muscle to the liver?

A

alanine

51
Q

Urea is formed from what 2 molecules?

A

CO2 and ammonia

52
Q

Where does the urea cycle take place?

A

liver

53
Q

How is the urea cycle regulated?

A

substrate availability ie- dietary protein

54
Q

Where do the 2 nitrogen atoms in urea come from?

A

ammonia, aspartate

55
Q

Which Krebs cycle intermediate is produced by the urea cycle?

A

fumarate

56
Q

what are the 4 major constituents of urine?

A

urea, ammonia, creatinine, uric acid

57
Q

What is the role of HCl in protein digestion?

A

denatures the protein and provides optimal pH for pepsinogen conversion to active pepsin

58
Q

What enzyme has optimum activity at pH2?

A

pepsinogen/pepsin

59
Q

What 3 aromatic amino acids have their peptide bonds hydrolyzed by pepsin?

A

Tyrosine, phenylalanine, tryptophan

60
Q

Enterokinase is the enzyme that activates which zymogen released by the pancreas?

A

trypsinogen

61
Q

Which enzyme activates all other enzymes released by the pancreas?

A

trypsin

62
Q

What is the overall fate of proteins that we eat?

A

form free amino acids and enter the liver via the portal blood system

63
Q

What is the role of brush border enzymes in protein digestion?

A

break down smaller peptides to release free amino acids that a readily absorbed

64
Q

Which bonds need to be broken for a peptide to become denatured?

A

weak and disulfide bonds (secondary structure)