Amino acid metabolism: Oxidation and Urea test 3 Flashcards Preview

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Flashcards in Amino acid metabolism: Oxidation and Urea test 3 Deck (39):
1

what is the process of removing ammonia from the body called?

the urea cycle

2

why are amino acids important?

because they are coded for the DNA and they make up proteins

3

what are the four fates of dietary AAs

-protein syn
-Energy production (CAC) (15-20% of total energy)
-Biosynthesis
-Urea excretion

4

what are the three drivers of Protein oxidation?

normal synthesis and degradation
protein rich diet
starvation or diabetes mellitus

5

what is the cycle that connects the urea cycle to the CAC?

Aspartate-arginino-succinate shunt of the CAC

6

what bonds(AAs) does pepsin target

phenylalanine
tyrosine
tryptophan

7

secretin does what?

stimulates release of bicarbonate from the pancreas

8

what does cholecystokinin do?

stimulates zymogen release from the pancreas

9

three fates of dietary protein enzymatically degraded to AAs?

protein synthesis
catabolized for energy within cells
transported to the liver and excreted

10

dietary proteins cause what to be released from the stomach?

gastrin from G cells, which causes chief cells to release pepsinogen and parietal cells to release HCl

11

where does most of the AA catabolism happen?

in the liver
basic strategy is to separate the amine group, and leave the carbon chain

12

what are the metabolically important AAs

Glutamine, Glutamate, Aspartate, Alanine
-Amine group carriers
-precursors and common metabolites
-entry and exit molecules from the CAC

13

How is ammonia toxic?

-it disrupts the Na/K ATPase in the CNS.
-astrocyte K uptake is disrupted
-high extracellular K prevents GABA(too much Cl in side cell)

14

how are amine groups stabilized?

urea or uric acid for excretion

15

in the transaminase rxn between alpha-ketogluterate and glutamate what enzyme does it and what stabilizes the amine group?

PLP-pyridoxal phosphate
Vitamine B6

16

when an AA transfers its amino group to alpha ketogluterate what is left?

alpha keto acid

17

what are the two major AA catabolism rxns?

transaminase and one-carbon transfers

18

what enzyme is responsible for glutamate becoming glutamine?

glutamine synthase

19

why is glutamine important?

non-toxic
most cells have glutamine synthetase
common synthetic precursor

20

how is intracellular ammonia buffered?

by converting glutamate to glutamine

21

what is the glucose-alanine cycle?

-pyruvate gets an amine group add by
alanine anminotransferase and becomes alanine.
-the amino group is coming from glutamate
-alanine then adds the amine group to alpha-ketogluterate in the liver which becomes glutamate and pyruvate is now in the liver.

22

why is the glucose-alanine cycle important?

allows for proteins to function as a energy source
occurs in anaerobic stress
**coincides with the cori cycle**

23

what is the purpose of the urea cycle?

to excrete liver nitrogen in the form of Urea
-requires enzymes within the mitochondria and cytoplasm
-four steps (five structural changes)
-ATP-dependent

24

what AA is absolutely essential for the urea cycle?

ornithine

25

what is the first step in the urea cycle?

Glutamine from the extrahepatic tissue
Alanine from the muscle
these the become gluatamate

26

once glutamate is in the mitochondrial matirx what happens?

glutamate then release ammonia to become carbamoyl phosphate
or
the amine group is added to oxaloacetate to become asparate

27

when ornithine adds an amine group to carbamoyl phosphate what is produced?

citrulline
**this occurs in the mitochondria

28

citrulline gets another amine group from aspartate and becomes what?

-arginine, **ATP dependent
-when this reacts with water urea is formed and we get ornithine once again.
*this occurs in the cytoplasm

29

what are the two levels of regulation for the urea cycle?

in the urea cycle itself and in the precursor step of making carbamoyl phosphate

30

where in the body are AAs glucogenic and ketogenic?

in the liver and only the liver

31

what are the six AAs degraded to pyruvate?
most energy rich

tyrptophan
alanine
cysteine
serine
glycine
threonine

32

what are the seven AAs degraded to Acetyl-
CoA?
second most energy rich

tryptophan
lysine
phenylalanine
tyrosine
luecine
isoleucine
threonine

33

what are the five AAs degraded into alpha-ketogluterate?
3rd most energy rich

glutamate
glutamine
proline
arginine
histidine

34

four AAs degraded to become Succinyl-CoA?
4th most energy rich

methionine
isoleucine
valine
threonine

35

what AAs are degraded to become oxaloacetate?
least energy rich

Asparagine and Asparate

36

what are the non essential AAs?

Alanine
Asparagine
Aspartate
Glutamate
Serine

37

what AAs are essential (always essential)
his
isometeric
leg
lifts
met
failure
three
tries
valiantly

histidine
isoluecine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valine

38

which AAs are conditionally essential?

arginine
cysteine
glutamine
glycine
proline
tyrosine

39

how is urea removed from body?

bile and urea