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2C MIDTERMS > BIOCHEM AMINO ACID > Flashcards

BIOCHEM AMINO ACID Flashcards

1
Q
  1. Which among the following is the 21st amino
    acid?
    A. Selenagomesteine
    B. Selenococysteine
    C. Selenocysteine
    D. Selenoprotein C
A

C. Selenocysteine

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2
Q
  1. Which among the following a.a. is
    hydrophobic?
    A. Arginine
    B. Alanine
    C. Asparagine
    D. Aspartic acid
A

B. Alanine

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3
Q
  1. This is the nucleotide triplet that encodes
    the 20 sets of L-α-amino acid?
    A. Post-translational modification
    B. Codon
    C. Genetic code
    D. UGA
A

B. Codon

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4
Q
  1. The condition is a result of a starchy rich
    poor protein diet:
    A. Kwashiorkor
    B. Scurvy
    C. Marasmus
    D. Menkes syndrome
A

A. Kwashiorkor

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5
Q
  1. This condition is the result of both caloric
    and specific amino acid intake is deficient:
    A. Kwashiorkor B. Scurvy
    C. Menkes Syndrome D. Marasmus
A

D. Marasmus

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6
Q
  1. Which of the following amino acid is the
    smallest:
    A. Alanine B. Aspartic acid
    C. Glycine D. Leucine
A

C. Glycine

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7
Q
  1. Which of the following enzyme catalyzes
    the transfer of the carbamoyl group of
    carbamoyl phosphate to ornithine?
    A. L-Ornithine transcarbamoylase
    B. D-Ornithine transcarbamoylase
    C. L-Transcarbamoyl ornithase
    D. D-Transcarbamoyl ornithase
A

A. L-Ornithine transcarbamoylase

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8
Q
  1. Proline does not participate in
    transamination:
    A. True B. False
A

A. True

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9
Q
  1. The condition is characterized by a urine
    sample that smells like burnt sugar:
    A. Maple syrup urine disease
    B. Burnt sugar urine syndrome
    C. Syrup accumulation urine syndrome
    D. Metabolic alkalosis
A

A. Maple syrup urine disease

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10
Q

_____________________ provide monomer units of the long polypeptide chains of proteins

A

L-α-Amino acids

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11
Q

________________ participate in the biosynthesis of porphyrins, purines, pyrimidines, and urea

A

L-α-Amino acids

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12
Q

therapeutic value of D-amino
acids

A
  • antibiotics bacitracin and gramicidin A
  • antitumor agent bleomycin
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13
Q

more than ______ amino acids occur in nature. Proteins are synthesized almost exclusively from the set of ______________________ encoded by nucleotide triplets called codons

A

300, 20 L-α-amino acids

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14
Q

All hydrophobic Amino Acids

A

Alanine
Isoleucine
Leucine
Methionine
Phenylalanine
Proline
Tryptophan
Tyrosine
Valine

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15
Q

*With the sole exception of glycine, the α-carbon of every amino acid is _______

A

chiral

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16
Q

all AA share the absolute configuration of ____________________ and thus are defined as L-α-amino acids

A

L- glyceraldehyde

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17
Q

*in mammals, the biochemical reactions of L-α-amino acids are catalyzed by enzymes that act exclusively on ___________

A

L-isomers

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18
Q

precursor of thyroid hormone

A

*Tyrosine

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19
Q

metabolized to
epinephrine, norepinephrine, and
dihydroxyphenylalanine (DOPA)

A

*Tyrosine and phenylalanine

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20
Q

neurotransmitter, precursor of γ-
aminobutyric acid (GABA)

A

*Glutamate

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21
Q

AA involved in urea biosynthesis

A

*Ornithine and citrulline

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22
Q

*Free __________ and __________ are found in human brain tissue

A

D-serine, D-aspartate

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23
Q

__________ and __________ are found in the cell walls of gram- positive bacteria

A

D-alanine, d-glutamate

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24
Q

an amino acid bears no net
charge

A

Isoelectric pH (pI)

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25
Q

solubility of amino acids reflects their _____________________

A

Ionic character

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26
Q

In aqueous solution, charged and uncharged forms of the ionizable weak acid groups ______________ and
__________ exist in dynamic protonic equilibrium:

A

—COOH, —NH3

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27
Q

both R—COOH and R—NH3 are ________ acids

A

weak

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28
Q

R—COOH is a far ________ acid than R—NH3

A

stronger

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29
Q

at ________________ (______), carboxyl groups exist almost entirely as R—COO- and amino groups predominantly as R—NH3

A

physiologic pH, pH 7.4

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30
Q

smallest amino acid; occurs where peptides bend sharply

A

glycine

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31
Q

The hydrophobic R groups

A

alanine, valine, leucine, and
isoleucine

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32
Q

The aromatic R groups

A

phenylalanine,
tyrosine, and tryptophan

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33
Q

number and order of the amino acid
residues in a polypeptide constitute its _________________________

A

primary structure

34
Q

derivatives of the carboxy terminal aminoacyl residue

A

peptides

35
Q

Nutritionally Essential Amino Acid

A

Arginine
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Proline
Threonine
Tryptophan
Valine

36
Q

Nutritionally Nonessential

A

Alanine
Asparagine
Aspartate
Cysteine
Glutamate
Glutamine
Glycine
Hydroxyproline
Hydroxylysine
Proline
Serine
Tyrosine

37
Q

AA that are tissue aminotransferases and can reversibly interconvert all three amino acids and their corresponding α-keto acids

A

Valine, Leucine, & Isoleucine

38
Q

present at the active site of several
human enzymes that catalyze redox
reactions

A

Selenocysteine

39
Q

Impairments in human ___________
have been implicated in tumorigenesis and atherosclerosis

A

selenoproteins

40
Q

The _________________ occupies a central position in protein and amino acid metabolism.

A

amino acid pool

41
Q

→Each amino acid is ________________ via its own unique pathway, but the general scheme is the same for each
one.

A

degraded

42
Q

General scheme for amino acid catabolism

A

→Removal of the amino group
→Use of nitrogen in synthesis of new nitrogen compounds
→Passage of nitrogen into the urea cycle
→Incorporation of the carbon atoms into compounds that
can enter the citric acid cycle

43
Q

→Our bodies do not store __________________ compounds and
_______________ is toxic to cells.

A

nitrogen-containing, ammonia

44
Q

→Amino nitrogen must either be incorporated into _____ and excreted,
or used in the synthesis of new ________________ compounds

A

urea, nitrogen-containing

45
Q

→The ___________ atoms of amino acids are converted to compounds that can enter the citric acid cycle.

A

carbon

46
Q

carbon atoms continue through the citric acid cycle to give ____ and _______ stored in ATP. About _________ of our energy is produced in this way.

A

CO2, energy, 10–20%

47
Q

→If not needed immediately for energy, the carbon- carrying intermediates enter storage as ___________, _______, or _____________.

A

triacylglycerols, glycogen, ketone bodies

48
Q

→In ____________________, the amino group of the amino
acid and the keto group of an α-keto acid
change.

A

transamination

49
Q

→A number of ___________ enzymes are responsible for “transporting” an amino group from one molecule to another.
→Most are specific for ______________ as the amino group acceptor and work with several amino acids.
→The α-ketoglutarate is converted to ___________, and the amino acid is converted to an ______________________.

A

transaminase, α-ketoglutarate, glutamate, α-keto acid

50
Q

is a key reaction in many
biochemical pathways.

A

→Transamination

51
Q

→Transamination reactions are _____________ and go easily in
either direction, depending on the
concentrations of the reactants.

A

reversible

52
Q

Conversion of an amino acid —NH2 group to an α-keto group, with removal of NH4
+.

A

→Oxidative deamination:

53
Q

_____________________ is highly toxic to living things and must be eliminated in a way that does no harm.

A

→Ammonia

54
Q

_______________ are able to excrete ammonia through their
gills directly into their watery surroundings.

A

→Fish

55
Q

→Mammals must find other ways to get rid of ammonia, and must first convert ammonia, in solution as ammonium ion, to nontoxic urea via
the _______________

A

urea cycle.

56
Q

→The conversion of ammonium ion to urea takes place in the _______________

A

liver.

57
Q

→From the Liver, urea is transported to the ___________ and transferred to _______ for excretion.

A

kidneys, urine

58
Q

→Ammonium ion, bicarbonate ion, and ATP combine to form ___________________ in the
mitochondrial matrix.

A

carbamoyl phosphate

59
Q

The Urea Cycle
→The first step of the urea cycle transfers the carbamoyl group, H2NC=O, from carbamoyl phosphate to ___________, an amino acid not found in proteins, to give ___________, another nonprotein amino acid.

A

ornithine, citrulline

60
Q

The Urea Cycle
→Both nitrogen atoms destined for elimination as urea are now bonded to the same carbon atom in ____________

A

argininosuccinate.

61
Q

The Urea Cycle
→Step 3 cleaves argininosuccinate into two pieces: _________, an amino acid, and ______________, which is an
intermediate in the citric acid cycle.
→In Step 4 the hydrolysis of _________ takes place to give urea and regenerate the reactant in Step 1 of the cycle,
____________

A

arginine, fumarate, arginine, ornithine.

62
Q

→Amino acids that are converted to acetoacetyl- CoA or acetyl-CoA enter the ________________ pathway, and are called __________________________

A

ketogenesis, ketogenic amino acids.

63
Q

→Those amino acids that proceed by way of oxaloacetate to the _____________________ pathway
are known as ______________________

A

gluconeogenesis, glucogenic amino acids.

64
Q

amino acids Post-translation allows them to perform _________________

A

specific functions

65
Q

Carrier of ammonia and of the carbons of pyruvate from skeletal
muscle to liver via the Cori Cycle

A

Alanine

66
Q

Constitutes a major fraction of free amino acids in plasma (together
with glycine)

A

Alanine

67
Q

Carrier of nitrogen atoms in urea biosynthesis
Guanidino group is incorporated into creatinine

A

Arginine

68
Q

Following conversion to ornithine, the carbon skeleton serves as a
precursor of the polyamines putrescine and spermine

A

 Arginine

69
Q

biosynthesis of coenzyme A 🡪
reacting with pantothenate to form
4-phosphopantothenoylcysteine

A

CYSTEINE

70
Q

incorporated into creatine

A

GLYCINE

71
Q

entire glycine molecule becomes atoms
4, 5, and 7 of the __________

A

purines

72
Q

biogenic amine; functions in allergic
reactions and gastric secretion

A

histamine

73
Q

Catalyzed by histidine decarboxylase

A

HISTIDINE

74
Q

principal source of methyl
groups in the body

A

S-adenosylmethionine

75
Q

catalyzed by methionine
adenosyltransferase (MAT)

A

METHIONINE

76
Q

precursor of peptidyl selenocysteine

A

SERINE

77
Q

genetic defects in cystathionine β-
synthase (PLP dependent)

A

homocystinuria

78
Q

potent vasoconstrictor and
stimulator of smooth muscle
contraction

A

serotonin

79
Q

■ regulate the activity of
certain enzymes of lipid
and carbohydrate
metabolism and proteins
■ signal transduction
cascades

A

Phosphoserine, Phosphothreonine,
and Phosphotyrosine

80
Q

■ occur in mitochondria
■ catalyzed by dimethyl
glycine dehydrogenase
■ may also arise from
methylation of glycine
(GNMT)
■ important sources of one-
carbon units

A

SARCOSINE

81
Q

inhibitory neurotransmitter

A

γ-Aminobutyrate

2C MIDTERMS (14 decks)

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