nitrogen

Question 1

do humans have a storage form of nitrogen?

Answer 1

• NO

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

Question 2

is nitrogen itself a reactive compound?

Answer 2

• YES

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

Question 3

how does most nitrogen leave the body

Answer 3

• via the urea cycle

- retain the carbon skeletons for other uses

Question 4

most nitrogens enter the body in the form of…

Answer 4

• amino acids

- amino acid pool

Question 5

human body input of amino acid pool

Answer 5

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

Question 6

human body output of amino acid pool

Answer 6

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

Question 7

is amino acid pool balanced>

Answer 7

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

Question 8

protein turnover in the human body

Answer 8

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

Question 9

proteasomes

Answer 9

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

Question 10

lysosomes

Answer 10

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

Question 11

what is the normal intake of dietary proteins>

Answer 11

100g/day

Question 12

where are dietary proteins digested?

Answer 12

• stomach

- small intestine

Question 13

stomach uses what enzyme?

Answer 13

pepsin

Question 14

small intestine uses what enzymes

Answer 14

-pancreatic enzymes and different ones in intestinal wall cells

Question 15

transamination

Answer 15

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

Question 16

transamination uses what enzyme?

Answer 16

aminotransferase

Question 17

oxidative deamination

Answer 17

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

Question 18

glutamine synthetase

Answer 18

• free NH3 us added to glutamate to glutamine

- happens in many tissues and transports it to the liver

Question 19

ALT

Answer 19

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

Question 20

urea cycle

Answer 20

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

Question 21

what supplies nitrogen to the urea cycle?

Answer 21

-ammonia and aspartate

Question 22

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

Answer 22

-glutamate

Question 23

hyperammonemia

Answer 23

• elevated levels of ammonia in the blood

- due to any defect in the urea cycle

Question 24

glucogenic

Answer 24

• 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

Question 25

Ketogenic

Answer 25

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

Question 26

conditionally essential amino acids

Answer 26

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

Question 27

essential/ non essential

Answer 27

essential-do not have enzymes to make it

non essesntial-can be synthesized by body

Question 28

elevated homocysteine

Answer 28

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

Question 29

homocysteinuria

Answer 29

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

Question 30

Albinism

Answer 30

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