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Biochemistry II > Bitch Ass Final Starting At Slide 94 > Flashcards

Bitch Ass Final Starting At Slide 94 Flashcards

1
Q

Cholesterol synthesis steps

A

1- Three acetate condense to form mevalonate

2- Mevalonate converts to phosphorylated 5-C isoprene

3- Six isoprenes (5C) polymerize to form the 30-C linear squalene

4- Squalene cyclists to form the four rings that are modified to produce cholesterol

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2
Q

Formation of acetoacetyl-CoA from acetyl-CoA is

Catalyzed by:

A

Thiolase or acetyl-CoA acyl transferase

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3
Q

Steps of formation of mevalonate from acetyl-CoA

A

Acetyl-CoA -> Acetoacetyl-CoA -> Betahydroxy-Beta-methylglutaryl-CoA (HMG-CoA) _> Mevalonate

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4
Q

Formation of HMG-CoA from acetoaetyl-CoA is catalyzed by:

What else is this used in?

A

HMG-CoA synthase

Mitochondrial HMG-CoA synthase is used in ketone body formation

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5
Q

formation of mevalonate from HMG-CoA is catalyzed by:

A

HMG-CoA Reductase

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6
Q

What is the rate limiting state of cholesterol synthesis?

A

formation of mevalonate

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7
Q

HMG-CoA reductase is a target for some _____ drugs

A

cardiovascular

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8
Q

Formation of mevalonate has a biproduct of how many NADPH?

How many NADP+?

A

2

2

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9
Q

In vertebrates, most cholesterol is synthesized in the ____ before being exported as:

A

liver

as bile acids, biliary cholesterol, or cholesteryl esters

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10
Q

Cholesterol made in tissues other than the liver is converted into ______

name some examples

A

steroid hormones

adrenal cortex– corticosteroids

Liver and kidney— Vitamin D

Gonads– testosterone and progesterone

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11
Q

What do stating drugs inhibit?

A

HMG-CoA reductase to lower cholesterol

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12
Q

How does statin inhibit HMGG-CoA reductase?

A

Statins resemble HMG-CoA -> competitive inhibitors of HMG-CoA reductase

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13
Q

First statin, _____, is found in ____

A

lovastatin

fungi

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14
Q

Statin drugs lower:

What are some side effects?

A

cholesterol by tens of percent

muscle weakness, coenzyme Q depletion

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15
Q

Statin drugs are also reported to improve:

A

circulation

stabilize plaques by removing cholesterol from them

reduce vascular inflammation

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16
Q

Insulin promotes ______ (____) of HMG-CoA reductase

While glucagon promotes ______ (____).

A

Dephosphorylation (activation)

phosphorylation (inactivation)

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17
Q

AMPK, when activated by low _____ relative to AMP, _____ and _____ HMG-CoA reductase

A

ATP

phosphorylates and inactivates

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18
Q

What stimulates proteolysis of HMG-CoA reductase?

A

Oxysterol metabolites of cholesterol (however it inhibits receptor mediated endocytosis)

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19
Q

Covalent modification of HMG-CoA reductase provides:

A

short term regulation

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20
Q

To form steroid hormones, cholesterol must first convert to ____, and then _____.

A

pregnenolone

progesterone

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21
Q

3 possible steroid hormones from progesterone

A

corticol (glucocoticoid)

Corticosterone (mineralcorticoid)

Testosterone

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22
Q

Cortisol affects:

A

protein and carbohydrate metabolism.

also supresses immune response, inflammation, and allergic responses

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23
Q

Corticosterone gets converted to ____. This regulates:

A

aldosterone

reabsorption of Na+, Cl-, HCO-3 (sodium, cholorine and bicarbonate ions) in the kidney

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24
Q

Testosterone can get converted to ___. These influence:

A

Estradiol

secondary sexual characteristics; regulare female repro cycle

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25
Q

Vitamin D3 production and metabolism:

A

1- 7-Dehydrocholesterol is exposed to UV light, converts to cholecalciferol (vitamin D3)

2- In the liver, a hydroxyl group is added at C-25

3- In the kidney, a second hydrozylation at C1 produces the active hormone, 1 alpha- dihydrozyvitamin D3 (calcitrol)

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26
Q

Active vitamin D3 regulates the metabolism of ___. Where?

A

Calcium

in kidney, intestine and bone

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27
Q

what can be made into over 20,000 products, including ubiquinone, carotenoids, vitamins K,E and A, Cholesterol and rubber?

A

Delta 3- isopentenyl pyrophosphate

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28
Q

What amino acids must be obtained as a dietary protein?

A

essential amino acids

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29
Q

what amino acids are required to some degree in young, growing animals. and/or sometimes during illness?

A

conditionally essential amino acids

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30
Q

Name the nonessential amino acids

A

Alanine

Asparagine

Aspartate

Glutamate

Serine

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31
Q

Name the conditionally essential amino acids

A

Arginie

Cysteine

Glutamine

Glycine

Proline

Tryrosine

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32
Q

Name the essential aminoacids

A

Histidine

isoleucine

Leucine

Lysine

Methionine

Phenylalanine

Theronine

Tryptophan

Valine

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33
Q

What are some foods that limit lysine?

A

Grains (rice) and nuts

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34
Q

What are some foods that limit methionine?

A

Legumes and vegetables

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35
Q

Metabolic pathway intermediates for glycolysis as precursors of amino acids

A

Pyruvate (alanine, valine, leucine, isoleucine)

3 phosphoglycerate (serine— glycine, cysteine)

phosphoenolpyruvate (Tryptophan, phenylalanine, tyrosine)

Erythrose 4-phosphate (tryptophan, phenylalanine)

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36
Q

Metabolic pathway intermediates as precursors of amino acids for citric acid cylcle

A

Alpha-ketogluterate (glutamate— glutamine, proline, arginie)

Oxaloacetate (aspartate– asparagine, methionine, lysine)

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37
Q

Metabolic pathway intermediates as precursors of amino acids for pentose phosphate pathway

A

ribose-5-phosphate (histidine)

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38
Q

What cuts protein into peptides in the stomach?

A

pepsin

39
Q

____ and ____ cur proteins and larger peptides into smaller peptides in the small intestine

A

trypsin and chymotrypsin

40
Q

What degrade peptides into amino acids in the small intestine?

A

aminopeptidase and carboxypeptidases A and B

41
Q

The cytoplasm of exocrine cells is completely filled with:

A

rough ER (the site of synthesis of the zymogens f many digestive enzymes)

42
Q

where are zymogens concentrated?

A

in membrane-enclosed transport particles called zymogen granules

43
Q

How are zymogens released into the lumen of the collecting duct by exocytosis?

A

When an exocrine cell is stimulated, its plasma membrane fuses with the zymogen granule membrane, releasing zymogens

44
Q

products of lipid hydrolysis in the small intestine enter the _____ system after:

A

lymphatic

their absorption by the intestinal mucosa

45
Q

Where does trypsin cleave?

A

arginine and lysine

46
Q

Where does chymotripsin cleave?

A 
Trp
Tyr
Phe
Met
Leu
47
Q

Where does elastase cleave?

A

alanine
glycine
serine

48
Q

Where does carboxypeptidase A cleave?

A

Ala
Ile
Leu
Val

49
Q

Where does carboxypeptidase cleave?

A

Arginine and lysine

50
Q

Trypsin is activated by _____. Trypsin then activates:

A

enteropeptidase

the rest of the enzymes in the small intestine

51
Q

What is the only enzyme that cleaves on the carboxy end of arginie and lysine?

A

Carboxypeptidase B

52
Q

What stimulates to release zymoges cleavage of dietary protain in the small intestine by pancreatic proteases?

A

Cholecystokinin and secretin (secreted by the small intestine)

53
Q

What pancreatic proteases are serine endopeptidases?

Which are exopeptidases?

what are they produced from?

A

Trypsin, chymotrypsin and elastase

Carbodypeptidase A and B

from an inactive zymogen

54
Q

What is transamination?

A

Transfer of the NH3 group from amino acid to alphaketogluterate

55
Q

What catalyzes transamination?

A

aminotransferases

56
Q

What serve as amino acid/keto acid pairs in transamination reactions?

A

glutamate and alpha-ketogluterate

57
Q

What is a carrier of and a temporary reservoir of NH3 in transamination?

A

L-Glutamate

58
Q

what uses PLP and alpha-ketogluterate/glutamate pair and generates alanine and pyruvate?

A

alanine aminotransferase (ALT)

59
Q

What uses PLP and alpha-ketogluterate/glutamate pair to form aspartate and oxaoacetate?

A

aspartate aminotransferase (AST)

60
Q

Alanine and aspartate aminotransferases are biomarkers of:

A

hepatic disease and trauma (liver function test)

and skeletal and cardiac muscle trauma

61
Q

Removal of the NH2 group from glutamate to yield alpha-ketogluterate and free NH3

A

Oxidative deamination

62
Q

What is the mitochondrial enzyme for oxidative dehydrogenase?

is this reversible?

what are its coenzymes?

A

Glutamate dehydrogenase

yes

NAD+ (Glutamate to alpha-ketogluterate)
NADPH (alpha-ketogluterate to glutamate)

63
Q

direct deamination is catalyzed by:
Its substrates are:
Its coenzyme is:

A

serine dehydratase

sereine and threonine

PLP

64
Q

oxidative deamination is the disposal of:
It loses ___ as ___.
Its coenzyme is:

A

amino acid

NH2 as NH3

NAD+

65
Q

Reductive amination coenzyme:

It is the incorporation of ____ group to form:

A

NADPH

NH2

glutamate in presence of high NH3 levels

66
Q

Nontoxic carrier of ammonia in circulation:

A

glutamine

67
Q

What is the major amino acid in circulation?

A

L-Glutamine

68
Q

What is the fate of glutamine in the liver?

A

Conversion to NH4+ by glutaminase

Then conversion of NH4+ to urea by urea cycle (then transported to the kidneys for excretion

69
Q

Excess ammonia in tissue is added to _____ to form _____- a process catalyzed by ____ ____

A

glutamate

glutamine

glutamine synthetase

70
Q

In the muscle, glucose yields ____.

A

pyruvate

71
Q

What happens in an anaerobic microenvironment in the muscle?

A

Lactic acid dehydrogenase (LDH) converts pyruvate to lactic acid

72
Q

Alanine serves as a carrier of _____ and of the cabon skeleton of _____ from skeletal muscle to the liver

A

ammonia

pyruvate

73
Q

Steps of the glucose-alanine cycle in the muscle

A

1- glycolysis yields pyruvate

2- lactic acid dehydrogenase converts pyruvate to lactic acid

3- Conversion of pyruvate to alanine with alanine aminotransferase

3- NH2 group of branched chain amino acids ends up in glutamate

4- Alanine synthesis- transfer of NH2 group from glutamate to pyruvate by ALT

5- Tranport of alanine to the liver

74
Q

Glucose-alanine cycle in the liver

A

Conversion of alanine to pyruvate

1- ALT transfers NH2 group of alanine to alpha-ketogluterate which results in pyruvate and glutamate

2- Synthesis of glucose from pyruvate via gluconeogenesis

3- Transport of glucose to the muscle

75
Q

What provides the carbon atom of urea?

A

bicarbonate (from carbon dioxide)

76
Q

What provides one of the nitrogen atoms of urea?

A

free ammonia

77
Q

This enzyme has an absolute requirement for N-acetyl-glutamate, which acts as an allosteric activator. It catalyzes the free ammonia to:

A

Carbamoyl phosphate synthetase I

Carbamoyl phosphate

78
Q

in urea cycle, Citrulline is synthesized from _____ and _____ with what enzyme?

what happens next?

A

Ornithine and carbamoyl phosphate

with omithine trans-carbomoylase

Citrulline is synthesized and transported out of the mitochondrion

79
Q

what provides the second nitrogen atom of urea?

A

the amino group of aspartate

80
Q

In urea cycle, how is aspartate made? What is done with it?

A

Fumerate is hydrolyzed to malate

Then oxidized to oxaloacetate

then transaminated to aspartate

Aspartate is added to citrulline to make argininosuccinate (with enzyme argininosuccinate synthetase)

81
Q

in urea cycle argininosuccinate uses enzyme _____ to form _____

A

arginino-succinate lyase

arginine

(Here, fumerate is released to be used to make aspartate)

82
Q

In urea cycle, arginine uses enzyme ______ to form _____

This also releases ____

A

arginase

ornithine

Urea

83
Q

In Urea cycle, ornithine is regenerated and transported into the _____

A

mitochondrion

here, it will react again with cirtrulline

84
Q

Again, what are the 2 N sources in urea?

A

NH3 (ammonia) and aspartate

85
Q

What captures free ammonia in the mitochondrial matrix for the urea cycle?

A

Carbamoyl phosphare synthetase I

86
Q

Allosterinc regulator in mitochondria

A

N-Acetylglutamate

87
Q

Fate of urea in the kidneys:

A

It is excreted in urine

88
Q

Fate of urea in intestine

A

Bacterial urease convertes it to CO2 and NH3

89
Q

Intestinal urease activity is seen in:

A

kidney failure patients

90
Q

What does hyperammonemia neurotoxic cause?

A

tremors, blurring of vision, cerbral edema, coma and death

91
Q

Ketogenic amino acids are converted to:

They are metabolized to:

A

ketone bodies

acetyl-coa or acetoacetyl-CoA

92
Q

What amino acids are strictly ketogenic?

A

leucine and lysine

all other amino acids are glucogenic

93
Q

Glucogenic amino acids are converted to:

They are metabolized to:

A

glucose

pyruvate, alpha-ketogluterate, succinyl-coa, fumerate or oxaloacetate

94
Q

what amino acids are both ketogenic and glucogenic?

A 
threonin
Isoleucine
Phenylalanine
Tryptophan
Tyrosine

Biochemistry II (7 decks)

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