Protein Metabolism (Lab) Flashcards

1
Q

T/F - Amino acids are not stored by the body (unlike fats and carbohydrates)

A

T

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2
Q

T/F - Amino acids must be obtained from the diet, synthesized de novo or produced from normal protein degradation

A

T

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3
Q

1st phase of AA catabolism

A

Removal of α-amino groups

Formation of ammonia and corresponding α-keto acid

Ammonia excreted in the urine or used to synthesize urea

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4
Q

2nd phase of AA catabolism

A

α-keto acids

common intermediates of energy producing metabolic pathways
(can be metabolized to CO2 and water, glucose, fatty acids, or ketone bodies)

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5
Q

Protein digestion starts in the ___

A

stomach

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6
Q

Dietary protein present in the stomach
stimulates the release of ___

A

gastrin

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7
Q

promotes secretion of pepsinogen and HCl/hydrochloric acid (has 3 functions)

A

Gastrin

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8
Q

FUNCTIONS OF HCL

A
  1. Antiseptic properties kill most bacteria
  2. Denaturing action “unwinds” globular
    proteins
  3. Acidic property leads to activation of
    pepsinogen
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9
Q

affects the hydrolysis of 10% peptide bonds

A

Pepsin

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10
Q

Production of ____ is stimulated by the passage
of small amounts of acidic protein content into the
small intestine

A

secretin

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11
Q

Secretin stimulates ____ production, which in turn helps neutralize acidified gastric content

A

bicarbonate (HCO3-)

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12
Q

Promotes secretion of pancreatic digestive
enzymes trypsin, chymotrypsin, and
carboxypeptidase in their inactive forms

A

secretin

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13
Q

also have their zymogen forms

A

Proteolytic Enzymes

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14
Q

Specific to N- and C-terminal cleavage of Phe and Leu

A

Pepsin (pH 1.3)

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15
Q

Specific to C-terminal cleavage of Lys and Arg

A

Trypsin

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16
Q

Specific to C-terminal cleavage of aromatic amino acids

A

Chymotrypsin

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17
Q

T/F - N terminal side - <amino> - C-terminal side</amino>

A

T

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18
Q

are transported into the bloodstream via active transport process

A

Liberated amino acids

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19
Q

The passage of polypeptides and small proteins across the ____ is uncommon in adults

A

intestinal wall

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20
Q

In _____, the transport of polypeptides allows the passage of proteins such as antibodies in
colostrum milk from a mother to a nursing infant to build up immunologic protection in the
infant

A

infants

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21
Q

Protein Digestion and Absorption Pathway

A
  1. Mouth - Saliva (No effect on digestion)
  2. Stomach - HCl (denatures protein; Pepsin (Hydrolyzes peptide bonds)
    –> Large Polypeptides
  3. Small Intestine - Trypsin, Chymotrypsin, Carboxypeptidase, Aminopeptidase (all hydrolyzes peptide bonds)
  4. Intestinal Lining - Active transport
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22
Q

total supply of free amino acids available for use in
the human body

A

The Amino Acid Pool

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23
Q

Amino Acid Utilization

SOURCES

A
  1. Amino acid degraded of body
    proteins
  2. Amino acids derived from dietary
    protein
  3. Synthesis of non-essential AA from
    intermediates of metabolism
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24
Q

Amino Acid Utilization

ROUTES OF DEPLETION

A
  1. Synthesis of body protein
  2. AA consumed for the synthesis of
    essential nitrogen-containing
    molecules
  3. Conversion of AA to glucose,
    glycogen, fatty acids, ketone
    bodies, or H2O + CO2
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25
Q

The repetitive process in which proteins are degraded and
resynthesized.

A

Protein Turnover

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26
Q

T/F - The rate of protein synthesis is just sufficient to replace the protein being degraded

A

T (Leads to hydrolysis and resynthesis of 300-400 g of body protein each day)

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27
Q

Biosynthesis of non-essential amino acids in the liver

the state that results when the amount of nitrogen taken into the
human body as protein equals the amount of nitrogen excreted from the body in waste
materials

A

Nitrogen balance

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28
Q

Protein degradation exceeds protein synthesis; Amount of nitrogen in urine exceeds consumed amount; Results in tissue wasting

A

Negative nitrogen imbalance

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29
Q

Rate of protein synthesis (anabolism) is more than
protein degradation (catabolism); Indicated by the synthesis of large amounts of tissue

A

Positive nitrogen imbalance

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30
Q

Uses for Amino Acids (4)

A

Protein synthesis

Synthesis of non-protein nitrogen-containing compounds

Synthesis of non-essential amino acids

Production of energy

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31
Q

Uses approximately 75% of free amino acids

A

Protein synthesis

32
Q

Synthesis of purines and pyrimidines; Synthesis of heme for
hemoglobin

A

Synthesis of non-protein nitrogen-containing compounds

33
Q

Essential amino acids
cannot be synthesized
due to the lack of an
appropriate carbon
chain

A

Synthesis of
non-essential amino
acids

34
Q

Amino acids are not
stored in the body
(excess are degraded)

A

Production of energy

35
Q

T/F - Each amino acid has a unique degradation pathway

A

T

36
Q

T/F - The amino nitrogen atom is removed and excreted from the body as urea

A

T

37
Q

T/F - The remaining carbon skeleton is converted to pyruvate, acetyl CoA, or a citric acid cycle intermediate

A

T

38
Q

Two stages of amino acid degradation:

A
  • Removal of the α-amino group
  • Degradation of the remaining carbon skeleton
39
Q

produced through transamination when α-ketoglutarate is
the amino group acceptor

A

Glutamate (Glutamate Production via Transamination)

40
Q

always utilized glutamine in its amino
transfers, as many amino acids have their respective keto-acid
equivalent which are derived from or are themselves Krebs cycle
intermediates

A

Aminotransferase

41
Q

Aminotransferase reaction uses
_____ as the amino group
acceptor.

A

α-ketoglutarate

42
Q

Reactions catalyzed during
amino acid catabolism: (2)

A

A. Alanine aminotransferase
(ALT) – transfers an amino
group from alanine

B. Aspartate aminotransferase
(AST) – transfers an amino
group from aspartate

43
Q

a biochemical reaction in which an
α-amino acid is converted to an α-keto acid with
release of an ammonium ion that occurs in the
mitochondria of the liver and kidney

A

Deamination

44
Q

Oxidative Deamination (2):

A

a. Disposal of amino acids
b. Synthesis of amino acids

45
Q

Transport of Ammonia to the Liver

  1. Tissues use ______ to combine ammonia with
    glutamate to form glutamine
A

glutamine synthase

46
Q

Transport of Ammonia to the Liver

  1. _____is then transported in the blood to the liver
A

Glutamine

47
Q

Transport of Ammonia to the Liver

  1. Cleavage is then done by ______ to produce glutamate
    and free ammonia
A

glutaminase

48
Q

Transport of Ammonia to the Liver (In the muscle)

Alanine is transported by the blood to the liver where it is
converted to _____

A

pyruvate

49
Q

the body’s only way to SAFELY remove ammonia
(NH3) from the body

A

Urea Cycle

50
Q

can be toxic, hence the need for its
removal

A

Ammonia build up

51
Q

mainly described as a series of biochemical reactions
in which urea is produced from ammonium ions and
aspartate as nitrogen sources

A

The Urea Cycle

52
Q

produced in the liver is transported via blood to
the kidneys and eliminated from the body in urine

A

Urea

53
Q

The Urea Cycle Processes (4):

A
  1. CARBOMOYL GROUP TRANSFER
  2. CITRULLINE-ASPARTATE CONDENSATION
  3. ARGININOSUCCINATE CLEAVAGE
  4. UREA FROM ARGININE HYDROLYSIS
54
Q
  1. CARBOMOYL GROUP TRANSFER

one of the sources
of fuel for the urea cycle

A

Carbamoyl Phosphate

55
Q

CARBOMOYL GROUP TRANSFER

How many ATP molecules are expended in
the formation of one carbamoyl
phosphate molecule?

A

2 (contains a
high-energy phosphate bond and is
formed in the mitochondrial matrix.)

56
Q

CARBOMOYL GROUP TRANSFER

The carbamoyl group of carbamoyl
phosphate is transferred to ornithine to
form ____

A

citrulline

57
Q
  1. CITRULLINE-ASPARTATE CONDENSATION

Citrulline is transported into the _____and reacts with _____to produce _______, utilizing ATP

A

cytosol, aspartate, argininosuccinate synthetase

58
Q
  1. ARGININOSUCCINATE CLEAVAGE

Argininosuccinate is cleaved to arginine and fumarate by the enzyme _______

A

argininosuccinate lyase

59
Q
  1. UREA FROM ARGININE HYDROLYSIS (3):
A

a) Hydrolysis of arginine produces urea
and regenerates ornithine under the
influence of arginase

b) The oxygen atom present in urea
comes from water

c) Ornithine is transported back to
mitochondria to be used in the urea
cycle

60
Q

Net Reaction

How many ATP molecules used in
the production of one urea molecule

A

4

61
Q

How many are consumed in the production of
carbamoyl phosphate

A

2

62
Q

The equivalent of two ATP
molecules is consumed in step
two of the urea cycle to give ___ and the ___

A

AMP and the PPi

63
Q

Relationship of the Urea Cycle and Krebs Cycle

A

Fumarate produced is
ultimately converted to
aspartate

  • Aspartate re-enters the
    urea cycle at step two
64
Q

Glucogenic and Ketogenic Amino Acids

____ removes the amino group
from an amino acid

A

Transamination/oxidative deamination

65
Q

An ______ that contains the skeleton of the amino acid is produced

A

α-keto acid

66
Q

Products formed are among a group of ____

A

seven intermediates (Four products are intermediates in the citric acid cycle; Three products are pyruvate, acetyl CoA, and acetoacetyl CoA

67
Q

Glucogenic and Ketogenic Amino Acids

The amino acids converted to citric acid cycle intermediates can serve as ______

A

glucose precursors

68
Q

Glucogenic and Ketogenic Amino Acids

The amino acids converted to acetyl CoA or acetoacetyl-CoA can contribute to the formation of ______

A

fatty acids

69
Q

An amino acid that has a
carbon-containing degradation product
that can be used to produce glucose via
gluconeogenesis

A

Glucogenic amino acids

70
Q

An amino acid that has a
carbon-containing degradation product
that can be used to produce ketone
bodies (only Leu and Lys are purely
ketogenic)

A

Ketogenic amino acids

71
Q

Glucogenic Nonessential Amino Acids (11):

A

Alanine
Arginine*
Asparagine
Aspartate
Cysteine
Glutamate
Glutamine
Glycine
Histidine*
Proline
Serine

72
Q

Glucogenic Essential Amino Acids (3):

A

Methionine
Threonine
Valine

73
Q

Glucogenic and ketogenic Nonessential amino acid (1):

A

Tyrosine

74
Q

Glucogenic and ketogenic Essential amino acid (3):

A

Isoleucine
Phenylalanine
Tryptophan

75
Q

Ketogenic Essential Amino Acids (2)

A

Leucine
Lysine