Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Physiology > Metabolism II > Flashcards

Metabolism II Flashcards

(75 cards)

Start Studying
1
Q

3 sources of free AAs?

A

1- injested protein
2- endogenous protein
3- biosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

T/F biosynthesis of AAs is sufficient to allow net synthesis of protein

A

FALSE-

ingest 55 g + biosynthesize 300g = stored as protein 300 g + excrete AAs 55 g

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

use of free amino acids

A

1- to make protein
2- incorporated into urea & excreted
3- carbon skeleton used for energy
4- used to make puridine/pyrimidine/heme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

describe nitrogen balance

A

nitrogen ingested (protein) - nitrogen excreted (urea) = 0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

things that would cause positive nitrogen balance

A

child growth, pregnancy, body building

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

things that would cause negative nitrogen balance

A

starvation, vegetarianism, trauma, infection, cancer, burn, sepsis, surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is transamination?

A

the transfer of amino group to alpha keto gluterate to form glutamate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what cofactor is required for transamination?

A

pyridoxal phosphate, derivative of B6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is glutamate broken down into to form urea?

A

aspartate & ammonia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

how is glutamate broken down into aspartate? what is the key enzyme?

A

glutamate + oxaloacete = akg + aspartate

aspartate transaminase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how is glutamate broken down into ammonia? what is the key enzyme?

A

glutamate + NDP+ + H20= NH4+ + akg + NADPH

glutamate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

where does urea biosynthesis primarily occur?

A

liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the major components of the urea cycle?

A
  • ornithine + cabamoyl phosphate - citrulline- argino-succinate- arginine- urea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the 1* regulated enzyme in the urea cycle?

A

caramoyl phosphate synthase I, regulated by N-acetyl glutamate (produced from glutamate)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what enzyme converts arginine to urea?

A

arginase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

2 things that go into urea cycle

A

cabamoyl phosphate, aspartate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

two things spit out of urea cycle

A

urea, fumerate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

which two AAs carry nitrogen to liver when AA metabolism occurs in other tissues?

A

alanine & glutamine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

difference between glucogenogenic & ketogenic carbon skeletons?

A

glucogenogenic- yields CAC intermediates, or pyruvate

ketogenic- yields acetyl coa, acetoacetyl coa, acetoacetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what two factors causes AA storage after a meal?

A

stimulation of protein synthesis by AAs & insulin; inhibition of degradation by insulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what happens to circulating AAs overnight?

A

decrease, lack of insulin allows for protein degradation & release of AAs for liver to use in glucogenogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is THF and what does it do?

A
  • reduced form of folic acid
  • involved in transfer of one-carbon units, on C-10 or C-5, in multiple metabolic pathways, including the biosynthesis of purines & thymidine (1 pyrimidine)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what disorder can a dietary deficiency of folate lead to?

A
  • reduced rate of DNA synthesis, erythrocyte precursors cells grow large but do not divide= megaloblastic anemia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what does the active form of THF required?

A

methylcobalamin (a derivative of B12)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
purines?
adenine & guanine
26
pyrimidines?
cytosine & uracil & thymine
27
what can be build from purines & pyrimidines?
- nucleoside- base + sugar (adenosine, guanosine) | - nucleotide- nucleoside + phosphate group (adenosine monophosphate)
28
difference between ribose and deoxyribose?
deoxyribose has no hydroxyl group on 2' carbon
29
5 molecules that provide atoms in purine ring
aspartate glycine, glutamine, Co2, FH4 derivative (tetrahydrofolate)
30
step in purine synthesis that creates the activated form of ribose 5 phosphate?
r5p----- ribosephosphate pyrophosephate kinase --- PRPP
31
step in purine synthesis which is the committed step, is highly regulated
PRPP------ glutamine PRPP amidotransferase ---- 5-phosphoribosylamine
32
branch point in purine synthesis
IMP can become AMP or GMP
33
things that regulated the committed step in purine synthesis
AMP, GMP (negative) | PRPP (positive)
34
how to target tumors using purine synthesis pathways
6-mercaptopurine- looks like adenine- tumor cells divide a lot, don't recycle purines as much, drug inhibits enzymes in purine synthesis pathway
35
3 things pyrimidines are synthesized from
aspartate, glutamine, CO2
36
regulated step in pyrimidine synthesis
glutamine + CO2 + 2ATP ------ carbamoyl phosphate synthetase II --------- carbamoyl phosphate
37
T/F Pyrimidine ring is synthesized first and then attached to ribose 5 phosphate
TRUE
38
precursor for synthesis of other pyrimidine nucleotides
UMP
39
what turns ribonucleoside 5' diphosphates to deoxyribonucleoside 5' diphosphates?
ribonucleotide reductase
40
when do deoxyribonucleotides increase in concentration?
during S-phase, when DNA synthesis occurs
41
what does 5-flurouracil do?
converts to fDUMP, inhibits thymidylate synthase which now can't convert dUMP to dTMP
42
what does methotrexate do?
inhibits dihydrofolate reductaste, which turns dihydrofolate (TOXIC) into tetrahydrofolate after the dUMP-dTMP reaction
43
what are the four bases DNA & RNA are broken down into?
uracil, thymine, guanine, hypoxanthine
44
what is the key enzyme in the salvage pathway? what is the hypoxanthine reaction?
HGPRT-ase | hypoanthine + PRPP --> IMP + PPi
45
what syndrome does a deficiency in HGPRT-ase result in?
Lesch-Nyhan (compulsive self-mutilation, gout)
46
what happens to the 10% of purines which aren't salvaged?
they're metabolized to uric acid via xanthine/xanthine oxidase
47
at the pH of urine, which form predominantes?
uric acid instead of urate (uric acid is less soluble than urate)
48
the condition excessive production of uric acid can lead to? what drug treats this?
gout | allopurinol
49
Tissues whqere heme biosynthesis is highest, what is the major use of heme in these tissues
bone marrow- hemoglobin | liver- cytochromes
50
describe the general structure of heme
4 pyrrole molecules linked with bridging carbons for form a porphyrin ring with a ferrous ligand in the center
51
2 molecules that contribute all the atoms for the organic portion of heme
carbon & nitrogen
52
2 things used in the first step of the heme biosynthesis pathway + enzyme + product
succinyl Coa glycine ALA synthase ALA
53
difference between prophyrinogens and porphyrins
phorphyrinogens- no double bonds at bridging carbons, colorless
54
T/F Porphyrinogens cannot be non-enzymatically oxidized to porphyrins
FALSE- can be oxidized by light
55
how is heme synthesis regulated?
heme inhibits its own synthesis
56
define porphyria
partial deficiency of an enzyme involved in heme biosynthesis increasing metabolic intermediates
57
which two intermediates of heme biosynthesis are increased in acute intermittent porphyria
ALA & phorphobilinogen (PBG)
58
what causes the photosensitivity in variegate porphia?
sunlight converts porphyrinogens into porphyrins which accumulate, further degraded by light, generating tissue-destroying singlet oxygen
59
what is heme degraded by?
phagocytic cells of the reticuloendolthelial system (MM's of spleen, bone marrow, liver)
60
what are the constituents of hemoglobin?
- heme- becomes Fe and bilirubin (cleared w/ albumin) | - globin- degraded into free amino acids
61
what is the product of porphyrin degradation by heme oxygenase
biliverdin-9-alpha
62
what is the product of biliverding reductase?
indirect/unconjugated bilirubin
63
what is hyperbilirubinemia?
bilirubin in serum > 1 mg/dL
64
when does hyperbilirubinemia become a clinical concern?
when unconjugated bilirubin rises above 25 mg/dL, it can enter the brain and cause toxic encephalopathy
65
for hemolysis, biliary obstruction and hepatitis/cirrhosis, which forms of bilirubin predominate?
hemolysis- unconjugated biliary obstruction- conjugated hepatitis/cirrhosis- both
66
what is the liver's role in drug metabolism?
drugs & their metabolites are made hydrophilic in two reactions
67
what are phase 1 reactions in the metabolism of drugs?
introduction of -OH or -COOH groups through oxidation
68
what is the enzyme required for phase 1 reactions?
NADPH- cytochrome P450 reductase
69
what happens phase 2 reactions in the metabolism of drugs?
products of phase 1 reactions are conjugated with compounds (e.g. glycine, sulfate) to make them more hydrophilic
70
Which of the following is false? A- The liver produces most of the circulating plasma proteins B- The liver breaks down ketone bodies for energy C- The liver plays an important role in the interconversion of amino acids D- The liver stores both copper and iron
B- liver doesn't have the enzymes to break down ketone bodies
71
what is another name for vitamin A? what is it transported in?
retinol | transported in chylomicrons
72
what role does the liver play in vit A use?
when rentinol levels decrease, the liver mobilizes vit A by hydrolyzing retinyl ester, which binds to retinol-binding protein and is secreted into the blood
73
where are the major vitamin D stores found? how is it transferred?
adipose tissue and skeletal muscle
74
what is the role of liver in the life of vitamin D?
liver activates vitamin D3 and synthesizes vitamin D binding protein
75
where is the major store of vitamin K? why is it needed in the hepatocyte?
skeletal muscle | needed for synthesis of prothrombin (clotting)

Physiology (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions