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Flashcards in nitrogen Deck (30):
1

do humans have a storage form of nitrogen?

-NO
-there is no protein that exists simply to store amino acids

2

is nitrogen itself a reactive compound?

-YES
-the body must get rid of any nitrogen above the needs

3

how does most nitrogen leave the body

-via the urea cycle
-retain the carbon skeletons for other uses

4

most nitrogens enter the body in the form of...

-amino acids
-amino acid pool

5

human body input of amino acid pool

-amino acids from dietary protein
-amino acids from protein turnover in the body
-synthesis of non-essential amino acids de novo

6

human body output of amino acid pool

-synthesis of proteins
-synthesis of nitrogen containing compounds
-use of the carbon skeleton of AA from energy

7

is amino acid pool balanced>

-YES
-input = output
-individual is in steady state

8

protein turnover in the human body

-different proteins have different half-lives
-misfolded or unstable proteins are degraded more rapidly
-half-life of a protein id determined by structure

9

proteasomes

-selectively degrade damaged or short-lived proteins
-energy dependent
-uses ubiquitin modification to target proteins for degradation

10

lysosomes

-nonselectively degrade intracellular and extracellular proteins
-literally anything that enters cell
-uses acid hydrolases to break down peptide bonds to amino acids

11

what is the normal intake of dietary proteins>

100g/day

12

where are dietary proteins digested?

-stomach
-small intestine

13

stomach uses what enzyme?

pepsin

14

small intestine uses what enzymes

-pancreatic enzymes and different ones in intestinal wall cells

15

transamination

-transfer of the amino acid alpha amino group to alpha ketoglutarate producing alpha keto acid and glutamate

16

transamination uses what enzyme?

aminotransferase

17

oxidative deamination

-liberation of the amino group as free amonia
-primarily occur in liver and kidney
-in mitochondria

18

glutamine synthetase

-free NH3 us added to glutamate to glutamine
-happens in many tissues and transports it to the liver

19

ALT

-transamination of pyruvate
-mainly in muscle cells
-goes to liver then turns back into pyruvate

20

urea cycle

-produces urea from ammonia
-primarily in liver
-2 mitochondrial reactions
-3 cytosolic reactions

21

what supplies nitrogen to the urea cycle?

-ammonia and aspartate

22

what is the immediate precursor for both sources of nitrogen form urea cycle?

-glutamate

23

hyperammonemia

-elevated levels of ammonia in the blood
-due to any defect in the urea cycle

24

glucogenic

-an amino acid that can be converted into pyruvate or an intermediate of the TCA cycle
-may be used as substrate for GNG and give increase in glucose formation in the liver

25

Ketogenic

-amino acid that can be converted into acetoacetate of precursor to acetoacetate

26

conditionally essential amino acids

-an amino acid that would normally be considered non essential but may become essential to meet an increased demand

27

essential/ non essential

essential-do not have enzymes to make it
non essesntial-can be synthesized by body

28

elevated homocysteine

-produced during methionine metabolism
-risk factor for occlusive vascular disease
-during pregnancy, increased incidence of neural tube defects

29

homocysteinuria

-deficiency of cystathionine synthase
-cant break down methionine, so it accumulates
-DISLOCATION OF LENS, glaucoma, cataracts, retinal detachment

30

Albinism

-defect in several different enzymes that are involved in conversion of tyrosine to melanin
-when deficiency is in tyrosinase, complete lack of pigment