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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
Vitamin D3 production and metabolism:
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)
26
Active vitamin D3 regulates the metabolism of ___. Where?
Calcium in kidney, intestine and bone
27
what can be made into over 20,000 products, including ubiquinone, carotenoids, vitamins K,E and A, Cholesterol and rubber?
Delta 3- isopentenyl pyrophosphate
28
What amino acids must be obtained as a dietary protein?
essential amino acids
29
what amino acids are required to some degree in young, growing animals. and/or sometimes during illness?
conditionally essential amino acids
30
Name the nonessential amino acids
Alanine Asparagine Aspartate Glutamate Serine
31
Name the conditionally essential amino acids
Arginie Cysteine Glutamine Glycine Proline Tryrosine
32
Name the essential aminoacids
Histidine isoleucine Leucine Lysine Methionine Phenylalanine Theronine Tryptophan Valine
33
What are some foods that limit lysine?
Grains (rice) and nuts
34
What are some foods that limit methionine?
Legumes and vegetables
35
Metabolic pathway intermediates for glycolysis as precursors of amino acids
Pyruvate (alanine, valine, leucine, isoleucine) 3 phosphoglycerate (serine--- glycine, cysteine) phosphoenolpyruvate (Tryptophan, phenylalanine, tyrosine) Erythrose 4-phosphate (tryptophan, phenylalanine)
36
Metabolic pathway intermediates as precursors of amino acids for citric acid cylcle
Alpha-ketogluterate (glutamate--- glutamine, proline, arginie) Oxaloacetate (aspartate-- asparagine, methionine, lysine)
37
Metabolic pathway intermediates as precursors of amino acids for pentose phosphate pathway
ribose-5-phosphate (histidine)
38
What cuts protein into peptides in the stomach?
pepsin
39
____ and ____ cur proteins and larger peptides into smaller peptides in the small intestine
trypsin and chymotrypsin
40
What degrade peptides into amino acids in the small intestine?
aminopeptidase and carboxypeptidases A and B
41
The cytoplasm of exocrine cells is completely filled with:
rough ER (the site of synthesis of the zymogens f many digestive enzymes)
42
where are zymogens concentrated?
in membrane-enclosed transport particles called zymogen granules
43
How are zymogens released into the lumen of the collecting duct by exocytosis?
When an exocrine cell is stimulated, its plasma membrane fuses with the zymogen granule membrane, releasing zymogens
44
products of lipid hydrolysis in the small intestine enter the _____ system after:
lymphatic their absorption by the intestinal mucosa
45
Where does trypsin cleave?
arginine and lysine
46
Where does chymotripsin cleave?
``` Trp Tyr Phe Met Leu ```
47
Where does elastase cleave?
alanine glycine serine
48
Where does carboxypeptidase A cleave?
Ala Ile Leu Val
49
Where does carboxypeptidase cleave?
Arginine and lysine
50
Trypsin is activated by _____. Trypsin then activates:
enteropeptidase the rest of the enzymes in the small intestine
51
What is the only enzyme that cleaves on the carboxy end of arginie and lysine?
Carboxypeptidase B
52
What stimulates to release zymoges cleavage of dietary protain in the small intestine by pancreatic proteases?
Cholecystokinin and secretin (secreted by the small intestine)
53
What pancreatic proteases are serine endopeptidases? Which are exopeptidases? what are they produced from?
Trypsin, chymotrypsin and elastase Carbodypeptidase A and B from an inactive zymogen
54
What is transamination?
Transfer of the NH3 group from amino acid to alphaketogluterate
55
What catalyzes transamination?
aminotransferases
56
What serve as amino acid/keto acid pairs in transamination reactions?
glutamate and alpha-ketogluterate
57
What is a carrier of and a temporary reservoir of NH3 in transamination?
L-Glutamate
58
what uses PLP and alpha-ketogluterate/glutamate pair and generates alanine and pyruvate?
alanine aminotransferase (ALT)
59
What uses PLP and alpha-ketogluterate/glutamate pair to form aspartate and oxaoacetate?
aspartate aminotransferase (AST)
60
Alanine and aspartate aminotransferases are biomarkers of:
hepatic disease and trauma (liver function test) and skeletal and cardiac muscle trauma
61
Removal of the NH2 group from glutamate to yield alpha-ketogluterate and free NH3
Oxidative deamination
62
What is the mitochondrial enzyme for oxidative dehydrogenase? is this reversible? what are its coenzymes?
Glutamate dehydrogenase yes NAD+ (Glutamate to alpha-ketogluterate) NADPH (alpha-ketogluterate to glutamate)
63
direct deamination is catalyzed by: Its substrates are: Its coenzyme is:
serine dehydratase sereine and threonine PLP
64
oxidative deamination is the disposal of: It loses ___ as ___. Its coenzyme is:
amino acid NH2 as NH3 NAD+
65
Reductive amination coenzyme: It is the incorporation of ____ group to form:
NADPH NH2 glutamate in presence of high NH3 levels
66
Nontoxic carrier of ammonia in circulation:
glutamine
67
What is the major amino acid in circulation?
L-Glutamine
68
What is the fate of glutamine in the liver?
Conversion to NH4+ by glutaminase Then conversion of NH4+ to urea by urea cycle (then transported to the kidneys for excretion
69
Excess ammonia in tissue is added to _____ to form _____- a process catalyzed by ____ ____
glutamate glutamine glutamine synthetase
70
In the muscle, glucose yields ____.
pyruvate
71
What happens in an anaerobic microenvironment in the muscle?
Lactic acid dehydrogenase (LDH) converts pyruvate to lactic acid
72
Alanine serves as a carrier of _____ and of the cabon skeleton of _____ from skeletal muscle to the liver
ammonia pyruvate
73
Steps of the glucose-alanine cycle in the muscle
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
Glucose-alanine cycle in the liver
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
What provides the carbon atom of urea?
bicarbonate (from carbon dioxide)
76
What provides one of the nitrogen atoms of urea?
free ammonia
77
This enzyme has an absolute requirement for N-acetyl-glutamate, which acts as an allosteric activator. It catalyzes the free ammonia to:
Carbamoyl phosphate synthetase I Carbamoyl phosphate
78
in urea cycle, Citrulline is synthesized from _____ and _____ with what enzyme? what happens next?
Ornithine and carbamoyl phosphate with omithine trans-carbomoylase Citrulline is synthesized and transported out of the mitochondrion
79
what provides the second nitrogen atom of urea?
the amino group of aspartate
80
In urea cycle, how is aspartate made? What is done with it?
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
in urea cycle argininosuccinate uses enzyme _____ to form _____
arginino-succinate lyase arginine (Here, fumerate is released to be used to make aspartate)
82
In urea cycle, arginine uses enzyme ______ to form _____ This also releases ____
arginase ornithine Urea
83
In Urea cycle, ornithine is regenerated and transported into the _____
mitochondrion here, it will react again with cirtrulline
84
Again, what are the 2 N sources in urea?
NH3 (ammonia) and aspartate
85
What captures free ammonia in the mitochondrial matrix for the urea cycle?
Carbamoyl phosphare synthetase I
86
Allosterinc regulator in mitochondria
N-Acetylglutamate
87
Fate of urea in the kidneys:
It is excreted in urine
88
Fate of urea in intestine
Bacterial urease convertes it to CO2 and NH3
89
Intestinal urease activity is seen in:
kidney failure patients
90
What does hyperammonemia neurotoxic cause?
tremors, blurring of vision, cerbral edema, coma and death
91
Ketogenic amino acids are converted to: They are metabolized to:
ketone bodies acetyl-coa or acetoacetyl-CoA
92
What amino acids are strictly ketogenic?
leucine and lysine all other amino acids are glucogenic
93
Glucogenic amino acids are converted to: They are metabolized to:
glucose pyruvate, alpha-ketogluterate, succinyl-coa, fumerate or oxaloacetate
94
what amino acids are both ketogenic and glucogenic?
``` threonin Isoleucine Phenylalanine Tryptophan Tyrosine ```

Biochemistry II (7 decks)

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