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Flashcards in Module 4 Deck (36)
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1
Q

Urea cycle occurs in which two places

mitochondria
cytosol
cytoplasm
ECM

A

mito and cytoplasm

2
Q

5 enzymes of the urea cycle

which 2 need ATP

A
CPS1 - carbomyl phosphate (2 ATP)
OTC - ornithine trans-carbonmylase 
ASS - argino-succinate synthetase (1 ATP) 
ASL - argino-succinase lyase
A - arginase
3
Q

AA —-> transamination —-> a-keto acid (which will be used in all metabolic intermediates for energy)

what molecule is involved in this process - ultimately leading to glutamate?

A

a-KG

4
Q

PLP enzyme - what does it do?

what are the 2 products of the reaction it’s in charge of?

A

COFACTOR: active Vit B6 - carbon and oxygen molecule swapping

alanine (AA) + a-KG (keto acid) —–AAT——> pyruvate + glutamate

AAT - alanine aminotransaminase (second reaction when the molecule is being broken down further (aspartate); the enzyme is ASPARTATE AT

5
Q

glutamate DH - converts a-KG to?

A

glutamate

6
Q

IN MUSCLE

glutamate + ATP + NH4 —> ______ + ADP

what enzyme?

A

glutamine

glutamine synthetase

7
Q

IN LIVER - OXIDATIVE DEAMINATION

glutamine –> NH4 + glutamate via - which enzyme?

glutamate (now inside the liver) —> a-KG + NH4 - which enzyme? thus releasing what?

A

glutaminase

glutamate DH - releasing that ammonia

8
Q

__ ATP per aspartate = _ATP/nitrogen

A

4

2

9
Q

Which one of these activates CPS1?

arginine
glutamate semialdehyde
ornithinine
n-acetyl-glutamate

A

N-A Glutamate (sole purpose in life to activate CPS1)

10
Q

Hemodialysis

A

means of decreasing ammonia in body and blood

11
Q

Folic acid is key to what?

A

nucleotides - prevent neural tube defects

12
Q

N5, N10 - METHLENE-TETRAHYDROFOLATE

wtf is this?

A

active form of folate

13
Q

Cystathionine synthase - related to what condition?

A

homocystinuria

homocystine build up (cannot make cystine)

14
Q

Phenylalanine hydroxylase and dihydrobiopterin reductase - related to what condition?

A

phenylketonuria

15
Q

Phenylalanine hydroxylase also associated with what other AA’s catabolism?

A

tyrosine

16
Q

polyphenol oxidase added to urine of patients with this condition - leading to black urine

A

alcaptonuria - related to melanin

17
Q

Uric acid is formed from the breakdown of pyrimidines or purines?

A

purines

18
Q

T or F: glutamate has no role in NT

A

F

19
Q

When the body is infected - positive or negative N balance?

A

-ve

20
Q

2 purine bases

3 pyrimidine bases

A

adenine - guanine

uracil, thymine, cytosine

21
Q

What happens if you cannot methylate uracil?

A

death - cannot replicate DNA

22
Q

Ribose + 5-P + ATP –> AMP + _______? via what enzyme?

A

PRPP

PRPP synthetase

23
Q

de novo purine synthesis

what is the key controlling enyzme?

A

glutamine phosphoribosyl amidotransfrase

24
Q

When making _MP = ATP is the energy source and glutamine is the nitrogen donor

When making _MP = GTP is the energy source and aspartic acid is the nitrogen donor

ATP Cost
Costs __ GTP to form AMP
Costs __ ATP to form GMP

A

GMP
AMP

1
2

25
Q

What enzyme aids in the production of deoxyribonucleotide (removes hydroxyl group from hte sugar)

A

ribonucleotide reductase

26
Q

____ will shut the enzyme down, a nucleotide will encourage other deoxyribonucleotides to be produced

A

dATP

27
Q

Purine Metabolism (Diseases)

SCID (Severe Combined Immunodeficiency) - what enzyme is dysfunctional?

A

SCID (Severe Combined Immunodeficiency)
o Adenosine deaminase is nonfunctional
o Can’t remove amino group from adenosine and convert adenosine to inosine o Deoxyadenosine and derivatives build up
o Loss of immune function – No T and B cells
o Cells can’t divide because we can’t replicate DNA

28
Q

Purine Metabolism (Diseases)

Lesch-Nyan Syndrome - what enzyme is dysfunctional?

A
•  Lesch-Nyan Syndrome 
o  Hypoxanthine guanine phosphoribosyltransferase is nonfunctional 
o  Increased levels of PRPP 
o  Decreased levels of GMP and IMP 
o  Increased de novo purine synthesis 
o  Purines and uric acid build up  
o  Potential for gout 
o  Mental retardation  
o  Self mutilation
29
Q

Purine Metabolism (Diseases)

Primary Gout - what enzyme is dysfunctional?

A

Primary Gout
o PRPP insensitive to feedback control
o HGPRT reduced (salvage pathway)
o Uric acid build up
o Pain in the joints - Often times severe pain in the big toe
o It often happens after a person has been partying – rich meals with lots of protein (DNA) and they go to bed and get
this terrible pain in the middle of the night in their big toe

o

30
Q

Purine Metabolism (Diseases)

Von Gierke’s Disease - what enzyme is dysfunctional?

A

Von Gierke’s Disease

§ Glucose 6 phosphatase and the transporter protein that allows G6P to enter the ER are not functioning
§ G6P builds up, encouraging the hexose monophosphate shunt which gives ribose 5 phosphate
§ Build up of Ribose 5P that leads to an excess of PRPP, which can override the controls for purine synthesis
and produce more IMP and GTP than necessary
§ The resultant nucleotides are not needed so they must be degraded which increases uric acid

31
Q

Purine Metabolism (Diseases)

Secondary gout - what enzyme is dysfunctional?

A

• Secondary Gout
o Diet and lifestyle play a role
o The kidney is not able to excrete uric acid as sufficiently as it should
o Initially it can give pain in the big toe
o Pain is so severe that the individual cannot sleep
o Genetic propensity for a build-up of uric acid
o If someone is overweight, circulation is not as good as it used to be
o Alcohol has a negative effect
o Can lead to dehydration
o Decrease in excretion of uric acid by the kidney
o Caviar can lead to increased risk of gout
o Gout attack can occur as they are lying down
o King’s were susceptible
o Lots of good food without any physical activity
o Kidney disease can also have an effect on gout
o Lifestyle changes are the best way to deal with gout
o Pharmaceuticals can be used
o Can also occur as a result of:
o Leukemia
o Chemotherapy
o Multiple myeloma
o Lead poisoning
o Kidney disease

32
Q

Tx for 2ndary gout = allopurinol; blocks what enzyme

A

xanthene oxidase

33
Q

T or F: folic acid is not involved in pyrimidine base

A

T

34
Q

T or F: carbamoylphospate synthetase I is one of the enzymes involved in pyrimidine formation

A

F - this is solely related to urea synthesis

35
Q

Build up of urea in the blood?

A

kidney failure

36
Q

build up of ammonia in the blood

A

liver failure