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BMSC 230 Metabolism > additional thoughts > Flashcards

additional thoughts Flashcards

1
Q

Which two desaturases do humans lack?

A

12 and 15

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1
Q

How many rounds of FA synthesis does it take to get palmitate?

A

7 - 4c added the first time, 2c added the rest

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2
Q

Additonal FA elongation and desaturation occurs in what part of the cell?

A

Endoplasmic reticulum

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3
Q

What proteolytic enzyme is in the stomach?

A

pepsin

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4
Q

What proteolytic enzymes are in the small intestine?

A

trypsin, chymotrypsin, elastase

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5
Q

Why is the pH of the stomach important?

A
  • zymogens become active at low pH, allowing them to act on amino acids and degrade them, acid also denatures proteins
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6
Q

What is the proteasome involved in digestion?

A

ubiquitin proteasome

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7
Q

What proteolytic enzyme is secreted from gastric cells?

A

pepsin(ogen)

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8
Q

What proteolytic enzyme is secreted from the pancreas?

A

trypsinogen, chymotrypsinogen, proelastase

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9
Q

What is excess ammonia in non liver tissues transported as? What happens after?

A

Glutamine
- glutamine synthetase adds an NH4 group to glutamate to make glutamine
- glutamine is shuttled into the liver
- glutamine is converted to glutamate in liver mito by glutaminase which releases NH4 to the urea cycle

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10
Q

What organ can excrete ammonia directly?

A

kidney

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11
Q

Aminotransferases can be used as diagnostic markers for?

A

liver damage, SGPT and AGOT diagnostic tests are used, elevated levels in blood can be markers for heardt attack

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12
Q

Nitrogen can be removed in what three forms?

A

ammonium, urea, uric acid

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13
Q

What can urea cycle enzyme deficiencies cause?

A

hyperammonemia or elevated NH4 in the blood, occurs with liver cirrhosis as well

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14
Q

What are two possible suplements for urea deficiencies?

A

benzoate and phenylbutyrate, bind to glycine and glutamine which can be peed out
- helps delete liver nitrogen pool

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15
Q

In the liver, what two amino acids can directly produce ammonia by breakdown?

A

serine and threonine

16
Q

What does maple syrup urine disease result from?

A

liver lacking branched chain aminotransferases, causing aa breakdown to occur in brain, toxic = deathq

17
Q

What is PKU disorder?

A

defect in phenylalanine hydroxylase - causes phenylalanine buildup in blood, sever mental defects

18
Q

What is the primary control point in nitrogen metabolism, what are three negative allosteric regulators?

A

glutamine synthetase, carbamoyl phosphate, alanine, CTP

19
Q

Glutamine synthetase is active in its ____ form

A

deadenylated

19
Q

Where does the CH3 group come from in the conversion of homocysteine to methionine?

A

N5 of thf

19
Q

What enzyme is the allosterically regulated control point for pyrimidine biosynthesis?

A

aspartate transcarbamoylase - carbamoylphosphate to carbamoyl aspartate

20
Q

After forming carbamoyl aspartate, what is the next step in pyrimidine synthesis?

A

conversion to dihydroorate via dihydroorotate synthetase

21
Q

What is PRPP and how is it formed?

A

Is ribose 5 phosphate with atp joining to drop off 2 po4 groups, formed by PRPP synthetase, used in pyrimidine and purine synthesis

22
Q

What is 5 fluorouracil?

A

suicide inhibitor of thymidylate synthetase - cant make TMP

23
Q

What is gout?

A

high blood levels of uric acid

24
Q

What causes lesch nyhan syndrome?

A

deficiency in HGPRT which is main enzyme in purine salvaging, severe disability

25
Q

How is PKU typically treated?

A

diet

26
Q

What two enzymes produce ammonia in the kidney?

A

glutamate dehydrogenase and glutaminase

27
Q

THF is involved in what two kinds of biosynthesis>

A

Methionine and thymidylate (pyrimidines)

28
Q

What is the main drug that can inhibit dihydrofolate reductase which turns dihydrofolate to tetrahydrofolate

A

methotrexate - treats arthritis and eczema

29
Q

What amino acid is procudes as a byproduct of methionine biosynthesis?

A

adenosine

30
Q

What amino acid is the source of methyl groups in methionine biosynthesis?

A

Homocysteine / N5 methylthf

31
Q

WHAT COFACTOR IS REQUIRED FOR METHIONINE BIOSYNTHESIS?

A

Coenzyme b12

32
Q

Why is arginine conditionally essential?

A

supplied by the urea cycle in the arginosuccinase reaction

33
Q

Biotin is a required cofactor for what enzyme

A

Acetyl CoA carboxylase

BMSC 230 Metabolism (7 decks)

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