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BIOCHEMISTRY S.Y. 2022-2023 (LAB&LEC) FLASHCARDS > Protein Metabolism (Lab) > Flashcards

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
The repetitive process in which proteins are degraded and resynthesized.
Protein Turnover
26
T/F - The rate of protein synthesis is just sufficient to replace the protein being degraded
T (Leads to hydrolysis and resynthesis of 300-400 g of body protein each day)
27
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
Nitrogen balance
28
Protein degradation exceeds protein synthesis; Amount of nitrogen in urine exceeds consumed amount; Results in tissue wasting
Negative nitrogen imbalance
29
Rate of protein synthesis (anabolism) is more than protein degradation (catabolism); Indicated by the synthesis of large amounts of tissue
Positive nitrogen imbalance
30
Uses for Amino Acids (4)
Protein synthesis Synthesis of non-protein nitrogen-containing compounds Synthesis of non-essential amino acids Production of energy
31
Uses approximately 75% of free amino acids
Protein synthesis
32
Synthesis of purines and pyrimidines; Synthesis of heme for hemoglobin
Synthesis of non-protein nitrogen-containing compounds
33
Essential amino acids cannot be synthesized due to the lack of an appropriate carbon chain
Synthesis of non-essential amino acids
34
Amino acids are not stored in the body (excess are degraded)
Production of energy
35
T/F - Each amino acid has a unique degradation pathway
T
36
T/F - The amino nitrogen atom is removed and excreted from the body as urea
T
37
T/F - The remaining carbon skeleton is converted to pyruvate, acetyl CoA, or a citric acid cycle intermediate
T
38
Two stages of amino acid degradation:
* Removal of the α-amino group * Degradation of the remaining carbon skeleton
39
produced through transamination when α-ketoglutarate is the amino group acceptor
Glutamate (Glutamate Production via Transamination)
40
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
Aminotransferase
41
Aminotransferase reaction uses _____ as the amino group acceptor.
α-ketoglutarate
42
Reactions catalyzed during amino acid catabolism: (2)
A. Alanine aminotransferase (ALT) – transfers an amino group from alanine B. Aspartate aminotransferase (AST) – transfers an amino group from aspartate
43
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
Deamination
44
Oxidative Deamination (2):
a. Disposal of amino acids b. Synthesis of amino acids
45
Transport of Ammonia to the Liver 1. Tissues use ______ to combine ammonia with glutamate to form glutamine
glutamine synthase
46
Transport of Ammonia to the Liver 2. _____is then transported in the blood to the liver
Glutamine
47
Transport of Ammonia to the Liver 3. Cleavage is then done by ______ to produce glutamate and free ammonia
glutaminase
48
Transport of Ammonia to the Liver (In the muscle) Alanine is transported by the blood to the liver where it is converted to _____
pyruvate
49
the body’s only way to SAFELY remove ammonia (NH3) from the body
Urea Cycle
50
can be toxic, hence the need for its removal
Ammonia build up
51
mainly described as a series of biochemical reactions in which urea is produced from ammonium ions and aspartate as nitrogen sources
The Urea Cycle
52
produced in the liver is transported via blood to the kidneys and eliminated from the body in urine
Urea
53
The Urea Cycle Processes (4):
1. CARBOMOYL GROUP TRANSFER 2. CITRULLINE-ASPARTATE CONDENSATION 3. ARGININOSUCCINATE CLEAVAGE 4. UREA FROM ARGININE HYDROLYSIS
54
1. CARBOMOYL GROUP TRANSFER one of the sources of fuel for the urea cycle
Carbamoyl Phosphate
55
CARBOMOYL GROUP TRANSFER How many ATP molecules are expended in the formation of one carbamoyl phosphate molecule?
2 (contains a high-energy phosphate bond and is formed in the mitochondrial matrix.)
56
CARBOMOYL GROUP TRANSFER The carbamoyl group of carbamoyl phosphate is transferred to ornithine to form ____
citrulline
57
2. CITRULLINE-ASPARTATE CONDENSATION Citrulline is transported into the _____and reacts with _____to produce _______, utilizing ATP
cytosol, aspartate, argininosuccinate synthetase
58
3. ARGININOSUCCINATE CLEAVAGE Argininosuccinate is cleaved to arginine and fumarate by the enzyme _______
argininosuccinate lyase
59
4. UREA FROM ARGININE HYDROLYSIS (3):
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
Net Reaction How many ATP molecules used in the production of one urea molecule
4
61
How many are consumed in the production of carbamoyl phosphate
2
62
The equivalent of two ATP molecules is consumed in step two of the urea cycle to give ___ and the ___
AMP and the PPi
63
Relationship of the Urea Cycle and Krebs Cycle
Fumarate produced is ultimately converted to aspartate * Aspartate re-enters the urea cycle at step two
64
Glucogenic and Ketogenic Amino Acids ____ removes the amino group from an amino acid
Transamination/oxidative deamination
65
An ______ that contains the skeleton of the amino acid is produced
α-keto acid
66
Products formed are among a group of ____
seven intermediates (Four products are intermediates in the citric acid cycle; Three products are pyruvate, acetyl CoA, and acetoacetyl CoA
67
Glucogenic and Ketogenic Amino Acids The amino acids converted to citric acid cycle intermediates can serve as ______
glucose precursors
68
Glucogenic and Ketogenic Amino Acids The amino acids converted to acetyl CoA or acetoacetyl-CoA can contribute to the formation of ______
fatty acids
69
An amino acid that has a carbon-containing degradation product that can be used to produce glucose via gluconeogenesis
Glucogenic amino acids
70
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)
Ketogenic amino acids
71
Glucogenic Nonessential Amino Acids (11):
Alanine Arginine* Asparagine Aspartate Cysteine Glutamate Glutamine Glycine Histidine* Proline Serine
72
Glucogenic Essential Amino Acids (3):
Methionine Threonine Valine
73
Glucogenic and ketogenic Nonessential amino acid (1):
Tyrosine
74
Glucogenic and ketogenic Essential amino acid (3):
Isoleucine Phenylalanine Tryptophan
75
Ketogenic Essential Amino Acids (2)
Leucine Lysine

BIOCHEMISTRY S.Y. 2022-2023 (LAB&LEC) FLASHCARDS (9 decks)

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