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Protein Metabolism Flashcards

1
Q

describe the units of protein, smallets to largest

A

amino acids make peptides that make proteins

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2
Q

what is the mnemonic to remember the essential amino acids?

A

PVT TIM HALL

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3
Q

give the 10 essential amino acids (PVT TIM HALL)

A
  1. Phenylalanine
  2. Valine
  3. Tryptophan
  4. Threonine
  5. Isoleucine
  6. Methionine
  7. Histidine
  8. Arginine
  9. Lycine
  10. Leucine
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4
Q

what are essential amino acids?

A

cannot be synthesized by the body, or cannot be synthesized at a high enough rate to meet the requirement; must be obtained from the diet

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5
Q

what are nonessential amino acids?

A

can be synthesized by the body at high enough rates to meet requirements

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6
Q

what are the 10 nonessential amino acids? (CAAATS GGGP)

A
  1. Cysteine
  2. Alanine
  3. Aspartate
  4. Asparagine
  5. Tyrosine
  6. Serine
  7. Glycine
  8. Glutamate
  9. Glutamine
  10. Proline
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7
Q

what are semi-essential amino acids?

A

non-essential, but synthesized from essential amino acids

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8
Q

give the 2 semi-essential amino acids and what they are synthesized from

A
  1. Tyrosine from Phenylalanine

2. Cysteine is from Methionine

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9
Q

how are semi-essential amino acids handled in nutrition?

A

feed enough of the essential amino acid that the semi-essential is synthesized from so that you meet not only essential requirements, but also semi-essential requirements or add more of semi-essential to diet to reduce need for essential (sparing effect)

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10
Q

where does protein digestion begin?

A

in the stomach

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11
Q

describe protein digestion in the stomach (3)

A
  1. HCL denatures (unfolds) protein to allow digestive enzymes access to the bonds between amino acids
  2. pepsinogen (from chief cells) is activated to pepsin
  3. pepsin breaks down protein into shorter chains (peptides)
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12
Q

describe protein absorption in the small intestine

A
  1. duodenum secretes cholecystokinin (CCK) when chyme enters the SI
  2. CCK acts on the pancreas to secrete trypsinogen. chymotrypsinogen, and procarboxypeptidase proenzymes
  3. enterokinase on brush border activated trypsinogen to trypsin
  4. trypsin activates chymotrypsinogen to chymotrypsin and procarboxypeptidase to carboxypeptidase
  5. trypsin, chymotrypsin, and carboxypeptidase break down large peptides into oligopeptides (10 amino acids or fewer)
  6. aminopeptidases on brush border break down oligopeptides into tripeptides, dipeptides, and free amino acids, all of which can be absorbed
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13
Q

what is the main difference about ruminant protein metabolism?

A

the microbe see the protein first!

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14
Q

what do rumen microbes do to dietary protein?

A

they completely break down dietary proteins and amino acids and resynthesize new ones to use for protein synthesis according to microbe needs

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15
Q

what happens to microbial protein after the rumen?

A

it moves on to the abomasum for digestion in the same process described before

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16
Q

how is protein absorption accomplished? (2)

A
  1. amino acid transporters

2. peptide transporters

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17
Q

name and describe the 2 amino acid transporters

A
  1. sodium-dependent: transport amino acid with one sodium into cell (or out of cell)
  2. sodium-independent: transport amino acid into cell without anything else (or out of cell), just facilitated diffusion
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18
Q

describe peptide transporters

A

transport di-/tri- peptides into cell with a H+

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19
Q

once inside the cell, what happens to di and tripeptides

A

intracellular aminopeptidases break down di and tri peptides into free amino acids that leave the cell via amino acid transporters and enter the hepatic protal system

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20
Q

what are the 6 functions of proteins and amino acids?

A
  1. maintain body structure
  2. facilitate mobility
  3. transport
  4. metabolism
  5. regulation
  6. immune function
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21
Q

how do proteins and amino acids function to maintain body structure?

A

they make up collagen in connective tissue

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22
Q

how do proteins and amino acids function to faciliate mobility?

A

they make up actin and myosin in muscles

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23
Q

how do proteins and amino acids function for transport?

A

amino acid and peptide transporters, lipoproteins, plus albumin and hemoglobin

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24
Q

how do proteins and amino acids function for metabolism?

A

all enzymes are proteins

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25
how do proteins and amino acids function for regulation?
protein hormones like insulin and glucagon regulate glucose levels
26
how do proteins and amino acids function in immunity?
complement proteins, antibody proteins, and cytokine proteins
27
is protein stored in any way?
no all protein is functional
28
what is nitrogen balance?
measuring nitrogen intake and nitrogen excretion to determine what is happening in the body in terms of protein metabolism
29
when does a positive nitrogen balance occur?
when nitrogen intake exceeds nitrogen excretion; occurs in cases of growth, work, and production
30
when does nitrogen equilibrium occur?
when nitrogen intake matches nitrogen excretion; occurs in maintenance, when not growing or producing
31
when does a negative nitrogen balance occur?
when nitrogen intake is less than nitrogen excretion; occurs in starvation as protein is broken down as an energy source and disease states
32
what is the issue with nitrogen balance?
it doesn't tell specifics, doesn't just tell protein metabolism because other nutrients contain nitrogen and you also don't know which proteins may be deficient or excess, but it's a good starting point
33
what is dynamic protein turnover?
continual degradation and resynthesis of body protein
34
what can amino acids be used for? (3)
1. protein synthesis 2. oxidized 3. used for synthesis of non-protein metabolites
35
describe protein synthesis, the centra dogma again
DNA is transcripted into mRNA which is translated into protein
36
what activates protein synthesis and in what state?
insulin in the fed state
37
describe proteinn degradation
intracellular proteases break down protein once different systems within cells mark proteins for degradation
38
when does protein degradation increase, for what purpose, and in what state?
increase due to high glucagon levels in the fasted, starvation state to make substrates for gluconeogenesis
39
give the 11 nonprotein functions of amino acids
1. nitric oxide 2. creatine 3. choline 4. histamine 5. taurine 6. glutathionw 7. coenzyme A 8. thyroid hormone 9. NAD 10. melatonin 11. carnitine
40
what AA does nitric oxide come from?
arginine
41
what is the function of nitric oxide?
vasodilation
42
what AA does creatine come from?
arginine
43
what is the function of creatine?
allows muscles to store ATP for furture contractions
44
what AA does choline come from?
serine
45
what is the function of choline?
acetyl choline stimulates skeletal muscle contraction
46
what AA does histamine come from?
histidine
47
what is the function of histamine?
vasodilation and release of granules
48
what AA does taurine come from?
cysteine
49
what is the function of taurine?
component of bile, is necessary for vision and function
50
in what animals is taurine not synthesized, what must be done instead?
cats, must supplement in diet
51
what AA is glutathione from?
cysteine
52
what is the function of glutathione?
necessary for the antioxidant function of selenium
53
what AA is coenzyme A from?
cysteine
54
what is the function of coenzyme A?
all the pathways
55
what AA is thyroid hormone from?
tyrosine
56
what is the function of thyroid hormone?
everything to do with metabolism
57
what AA is NAD from?
tryptophan
58
what is the function of NAD?
also all the pathways
59
what AA is melatonin from?
tryptophan
60
what is the function of melatonin?
sleepipoo
61
what AA is carnitine from?
lysine
62
what is the function of carnitine?
the carnitine cycle
63
where does amino acid oxidation occur?
in the liver
64
in terms of oxidation, what are the two types of amino acids?
ketogenic and glucogenic
65
what are ketogenic amino acids?
they are oxidized to acetyl CoA, which enters the CA cycle, FA synthesis or ketogenesis
66
which two amino acids are ONLY ketogenic?
lysine and leucine
67
what are glucogenic amino acids?
oxidized to citric acid cycle intermediates
68
what 4 amino acids are BOTH ketogenic and glucogenic?
1. tryptophan 2. phenylalanine 3. tyrosine 4. isoleucine
69
how many amino acids are glucogenic?
18, including the 4 that are both ketogenic and glucogenic
70
how do fish excrete nitrogen (from amino acids)?
as ammonia, no conversion necessary
71
how do birds excrete nitrogen?
birds convert ammonia to uric acid that is then excreted
72
how do mammals excrete nitrogen?
they convert ammonia to urea, which is excrete in the urine
73
why must nitrogen be excreted?
it is toxic to the body
74
what must you keep in minding when supplementing amino acids to the diet?
must ensure that the nitrogen can be excreted from the body and don't overfeed protein

Nutrition (19 decks)

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