Protein Metabolism PPT Flashcards

1
Q

Not stored in the human body, they are constantly broken down into their constituent amino acids and then reused for protein synthesis.

A

Protein

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2
Q

Excess of this are not stored! but rapidly degraded for the synthesis of glucose (glycolosis) and lipids. Degradation of excess this causes an excess of nitrogen.

A

Degradation (Catabolism of AA)

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3
Q

Nitrogen excess is transformed into urea (80%) and ammonium (NH4 +) in order to be thrown away in the urine. (Liver and Blood)

A

Waste

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4
Q

Protein breakdown begins in the _______

A

stomach

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5
Q

No protein hydrolyzing enzymes are found in _______

A

saliva

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6
Q

Hydrolysis (10% of peptide bonds) & denaturization by _____ & ____ produce short chain polypeptides in the stomach.

A

pepsin enzyme & HCl acid

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7
Q

enzymes from pancreatic juices

A

Trypsin, chymotrypsin, & carboxypeptidase

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8
Q

also an from Pancreatic juices, it is from cells in the small intestine Brush Zone create “free” amino acids.

A

Aminopeptidase

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9
Q

Chemical digestion: it is produced in the pancreas

A

Pancreatic juice

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10
Q

2 pancreatic enzymes

A

Trypsin and Chymotrypsin

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11
Q

The total supply of free amino acids available is called

A

Amino Acid Pool

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12
Q

3 sources of “free” amino acids

A

Dietary protein breakdown
Biosynthesis of amino acids in the Liver
Protein turnover

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13
Q

is the breakdown & re-synthesis of body protein:
Old tissues
Damage
Recycling enzymes & hormones

A

Protein turnover

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14
Q

It’s in the mouth, it has no effect on digestion

A

Saliva

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15
Q

In the stomach, which denatures protein

A

HCl

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16
Q

It hydrolyzes peptide bonds

A

Pepsin

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17
Q

From large polypeptides to

A

oligopeptides

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18
Q

Amino acids in the small intestine

A

Trypsin, Chymotrypsin, Carboxypeptidase, Aminopeptidase

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19
Q

Dietary protein entering the stomach effects the release of the hormone _______ by stomach mucosa cells

A

gastrin

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20
Q

its antiseptic properties kill most bacteria

A

Hydrochloric acid

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21
Q

its denaturing action “unwinds” globular proteins, making peptide bonds more accessible to digestive enzymes

A

Hydrochloric acid

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22
Q

its acidity leads to the activation of pepsinogen, which is the inactive form of the digestive enzyme pepsin

A

Hydrochloric acid

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23
Q

Passage, in small batches, of the stomach’s acidic protein contents into the small intestine stimulates production of the hormone ________, which in turn stimulates pancreatic production of bicarbonate ion, HCO3, whose function is neutralization of gastric hydrochloric acid

A

secretin

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24
Q

secreted by intestinal mucosal cells, also attacks peptide bonds

A

Aminopeptidase

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25
Pepsin, trypsin, chymotrypsin, carboxypeptidase, and aminopeptidase are all examples of
proteolytic enzymes
26
Two steps in degrading amino acids
1) remove α-amino group 2) breakdown & process carbon skeleton
27
Release of an amino group is also two steps:
1) Transamination 2) Oxidative deamination
28
Four amino acids of central role of glutamate:
glutamate, aspartate, alanine and glutamine
29
present in mammalian cells at much higher concentrations than the other 16
glutamate, aspartate, alanine and glutamine
30
function as excitatory neurotransmitters in the central nervous system, and glutamate is partly responsible for the flavour of food. (It is the mono sodium glutamate listed on processed food labels.)
Glutamate and aspartate
31
occupies a special position in amino acid breakdown, and most of the nitrogen from dietary protein is ultimately excreted from the body via the glutamate pool.
glutamate
32
present in higher concentrations in mammalian cells. Have metabolic functions as well as roles in proteins.
Glutamate, aspartate, alanine & glutamine
33
Escapes in large amounts from dead or dying liver tissue. Measured in blood samples for diagnostic purposes
alanine aminotransferase
34
Very active enzyme, exists in mitochondrial and cytosolic variants. The detailed iso-enzyme pattern is tissue-specific.
Glutamate: pyruvate transaminase [GPT]
35
is the principal amino acid released from muscle tissue during starvation. It is an important substrate for hepatic gluconeogenesis
Alanine
36
required for the proper maintenance of fasting blood glucose concentrations.
Alanine transamination
37
very active enzyme inside heart cells. Also escapes in large amounts from dead or dying heart tissues & enters bloodstream. Measured in blood for diagnosing myocardial infarction.
aspartate aminotransferase
38
It exists in mitochondrial and cytosolic variants, and the detailed iso enzyme pattern is tissue-specific. It escapes in large amounts from dead or dying tissues and enters the bloodstream, so it is often measured in blood samples for medical diagnostic purposes. The metabolic importance of this enzyme is that it brings about a free exchange of amino groups between glutamate (which is the most common amino acid) and aspartate which is a second major amino acid pool.
Glutamate: oxaloacetate transaminase [GOT]
39
_______ and _______ are each required for separate but essential steps in the urea cycle, which is responsible for ammonia detoxication and nitrogen excretion.
Glutamate and aspartate
40
Most transaminases share a common substrate and product (oxoglutarate and glutamate) with the enzyme __________
glutamate dehydrogenase
41
has a central role in the overall control of nitrogen metabolism.
Glutamate
42
The glutamate produced from the transamination step is then deaminated by __________ using the enzyme glutamate dehydrogenase
oxidative deamination
43
Recycles back to a ketodiacid & releases ammonia
Oxidative Deamination
44
will reversibly convert glutamate to α-ketoglutarate and α-ketoglutarate to glutamate.
Glutamate dehydrogenase [GluDH]
45
Deamination reaction uses
NAD+
46
reverse reaction uses
NADPH
47
converting glutamate to α-ketoglutarate is an easily shifted equilibrium reaction.
Oxidative deamination
48
building up favors the synthesis of excessive amounts of glutamate, decreasing the Krebs cycle intermediate α-ketoglutarate.
Ammonium ions
49
What are the inputs to the urea cycle
NH3, CO2, and aspartic acid and fumaric acid
50
__________ from the urea cycle enters the Krebs cycle
Fumarate
51
________ produced from oxaloacetate of the Krebs cycle enters the urea cycle.
Aspartate
52
takes off amine groups from amino acids and forms glutamate (ionized glutamic acid)
Transamination
53
Amine groups form ________ when removed in deamination
ammonia
54
Spiders excrete _______, 5 nitrogen atoms in a small molecule.
guanine
55
Reptiles & birds excrete ______ – very insoluble purine compound – forms supersaturated solutions.
uric acid
56
Transamination or Oxidative deamination both produce _________
α-keto acids
57
Amino acid C skeletons that degrade to form a Krebs cycle intermediate can then be used to make glucose via gluconeogenesis. These are called:
Glucogenic Amino Acids
58
Amino acid C skeletons that degrade to form acetyl CoA or Acetoacetyl CoA can form fatty acids or ketone bodies. These are called
Ketogenic Amino Acids.
59
Use glycolysis intermediates:
3-phosphoglycerate & pyruvate
60
Krebs cycle intermediates:
Oxaloacetate & α-ketoglutarate
61
Defective phenylalanine hydroxylase – phenylalanine accumulates in body. Phenylalanine is transaminated to phenylpyruvate.
Phenylketonuria (PKU)
62
Iron atom stored in a protein
ferritin
63
degraded to bile pigments
Tetrapyrrole
64
Central methylene bridge of Biliverdin is reduced creating _______. It is found to be the major antioxidant in blood
Bilirubin
65
_______ transported to liver. Becomes more water soluble with attachment of glucoronide sugars to propionate side chains
Bilirubin
66
Intestinal bacteria help change Bilirubin into ______ and _______ for excretion.
Stercobilin and urobilin
67
Changing color of a bruise shows dominant degradation product of heme: either _____ or _____
biliverdin or bilirubin
68
when bilirubin accumulates in the blood. Spleen is degrading heme, but liver isn’t removing the product
Jaundice
69
the Brain uses ______or _______bodies for fuel.
Glucose or Ketone