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ASDOH Metabolism > Week 2 > Flashcards

Week 2 Flashcards

1
Q

A cholesterol derivative that is a component of bile salts.

A

What is Cholic acid?

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2
Q

Cholesterol is synthesized in four phases, all of which occur in the_________.

A

cytoplasm

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3
Q

the key regulatory enzyme in Cholesterol Biosynthesis:

A

HMG CoA Reductase

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4
Q

First the precursor of cholesterol is________ (6C), and synthesized by the condensation of 3 molecules of _______.

A

mevalonate

acetyl-CoA

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5
Q

Step 1: of Cholesterol Synthesis

A

Mevalonate (6C) Formation

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6
Q

tep 2: of Cholesterol Synthesis

A

Formation of an Isoprenoid (5C)

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7
Q

The cost of forming an Isoprenoid (5c)

A

Start with Mevalonate (6c)

3 ATP
1 Decarboxylation
6c Mevalonate

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8
Q

Step 3 of Cholesterol Synthesis

A

Condensation of Isoprene into Squalene (30c)

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9
Q

Step 4 of Cholesterol Synthesis

A

Cyclization of Squalene to Lanosterol and then 19 more steps, while losing three carbons to make cholesterol.

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10
Q

HMG-CoA is produced independently in mitochondria and in cytosol.__________ HMG-CoA is used to make ketone bodies._________ HMG-CoA is used to make cholesterol.

A

Mitochondrial

Cytosolic

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11
Q

The Enzyme that uses HMG-CoA to make ketone bodies

A

HMG-CoA lyase

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12
Q

The Enzyme that uses HMG-CoA to make Cholesterol

A

HMG-CoA reductase

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13
Q

Name the Bile salts derivatives of cholesterol

A

Glycocholate (glycine on C-17)

and

Taurocholate (tourine on C-17)

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14
Q

Classes of steroids from Cholesterol

A

Progestagens
Glucocorticoids
Mineralocorticoids
Androgens/Estrogens

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15
Q

An important intermediate molecule

pivotal between TAGs and phospholipids

A

phosphatidate

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16
Q

ω -6 and ω-3 series Eicosanoids

compete for same enzymes. What are they? (3)

A

cyclooxygenase
5-Lipoxygenase
Leukotrienes

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17
Q

Essential Glucogenic AA’s

A

Histidine
Methionine
Threonine
Valine

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18
Q

Glucogenic and Ketogenic Essential AA’s

A

Isoleucine
Phenylalanine
Tryptophan

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19
Q

Essential Ketogenic AA’s

A

Leucine

Lysine

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20
Q

Pepsinogen (Zymogen) activates

A

–> Pepsin

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21
Q

Protein leaving stomach stimulates_________ release in the duodenum, triggering the release of the main digestive enzymes by the pancreas.

A

cholecystokinin

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22
Q

Cholecystokinin (CCK) stimulates

A
  • gall bladder bile release
  • Release of pancreatic digestive enzymes
  • Slows down gastric empting
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23
Q

__________(duodenum hormone) activates release of basic solution from pancreas

A

Secretin

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24
Q

Cuts Arginine and Lysine residues,

A

Trypsin

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25
Q

Cuts Aromatic amino acids

A

Chymotrypsin:

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26
Q

Cuts Hydrophobic amino acids

A

Elastase

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27
Q

Determinants of Protein Longevity

A

Oxidation
PEST sequences (Proline, Glutamate, Serine, Threonine)
Amino terminus sequence (N-terminal rule)

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28
Q

PEST sequences

A

Proline, Glutamate, Serine, Threonine

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29
Q

Other proteins are broken down by being tagged by a protein called_________ and degraded by the_____________.

A

ubiquitin

proteasome

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30
Q

Duodenum enzyme, converts pancreatic trypsinogen to trypsin.

A

Enteropeptidase

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31
Q

Transfer of amino groups (usually to α- ketoglutarate) is catalyzed by ___________

And these require the coenzyme ____________

A

aminotransferases

pyridoxal phosphate (vitamin B6)

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32
Q

Catalyzes transfer of the amino group of alanine to α-ketoglutarate to form pyruvate and glutamate.

A

Alanine aminotransferase (ALT)

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33
Q

Exception to the rule that aminotransferases funnel amino groups to form glutamate. Transfers amino groups from glutamate to oxaloacetate, forming aspartate.

A

Aspartate aminotransferase (AST)

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34
Q

________is the only amino acid that undergoes rapid oxidative deamination, a reaction that is catalyzed by ______________ ________.

A

Glutamate

glutamate dehydrogenase

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35
Q

_______________________ requires N- acetyl glutamate for activity, whose concentration increases after a protein rich meal

A

Carbamoyl phosphate synthetase I

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36
Q

____________links the Urea cycle with Gluconeogenesis and Transamination of Oxaloacetate

A

Fumarate

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37
Q

The enzyme_________ cleaves Arginine to Ornithine and Urea occurs almost exclusively in the______.

A

Arginase

liver

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38
Q

Cost of the urea cycle:

A

4 high energy phosphate bonds broken.

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39
Q

After glutamine reaches the liver:

Glutamine + H2O —-> Glutamate + NH4+

This reaction is catalyzed by the enzyme________

A

Glutaminase

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40
Q

Ammonia is also transported from muscle to liver in the form of_______

A

alanine

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41
Q

In muscle tissue Alanine is formed by the transamination of_________ to_______.

Once in the liver alanine reacts with _________ to reform “______” and “__________” (Alanine aminotransferase).

A

glutamate to pyruvate

α-ketoglutarate

pyruvate and glutamate

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42
Q

Acquired hyperammonemia: usually due to _____ _______.

A

liver cirrhosis

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43
Q

What is the general chemical composition and source of folic acid.

A

a. Pteridine
b. PABA (pSaminobenzoate)
c. Glutamate

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44
Q

Dietary Folic Acid Is catalyzed by ________ to tetrahydrofolate by Breaking double bonds to__ and replacing with __

A

(dihydrofolate reductase)

N replacing with H+

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45
Q

Lack of folic acid is the most common
vitamin deficiency in the world. Because blood
cells turn over rapidly, folate deficiencies usually
seen first as __________ _________.

A

megaloblastic anemia

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46
Q

Tetrahydrofolate is Required for…

A

Required for purine, thymine and

amino acid metabolism.

47
Q

The most reduced group carried by Tetrahydrofolate.

A

-CH3 Methyl (N5)

48
Q

The intermediate group carried by Tetrahydrofolate.

A

-CH2- Methylene (N5-N10 bridge)

49
Q

The most oxidized group carried by Tetrahydrofolate.

A
  • CHO Formyl (N5 or N10)
  • CHNH Formimino (N5)
  • CH= Methenyl (N5-N10 bridge)
50
Q

S-Adenosylmethionine (SAM) is synthesized from Synthesized from___ ATP and__________. All the phosphate is removed

A

3 ATP Equivalents

methionine

51
Q

_______________________ is the rate limiting step of the methyl cycle.

A

Methylene tetrahydrofolate reductase

52
Q

Glutamine is formed from

glutamate by ________.

A

glutamine synthetase

53
Q

Serine is the major biosynthetic precursor of both________ and________.

A

glycine

cysteine

54
Q

The important antioxidant ________ is made from cysteine

A

Glutathione

55
Q

Enough_______ is synthesized by the urea cycle to meet the needs of an adult but not those of a growing child.

A

arginine

56
Q

Tyrosine can be produced from the essential amino acid phenylalanine in a single step catalyzed by _____________.
Reaction requires molecular oxygen and coenzyme______________

A

Phenylalanine hydroxylase

tetrahydrobiopterin

57
Q

Which tissues does Heme synthesis mostly take place in?

A

In the liver and bone marrow.

58
Q

Disease where porphryin intermediates build up and heme is not formed

A

Porferers (king George III had this)

59
Q

3 allosteric (negative) effectors of Hemoglobin

A
  1. –BPG 2
  2. H+
  3. CO2
60
Q

2,3 -BPG binds
converting__ state to___ state and
favoring oxygen ______.

A

R
T
Release

61
Q

In the smoker, high ______ is still
present in the hemoglobin in the
lungs, remaining in the ___ state.

A

2,3-BPG

T

62
Q

Fetal hemoglobin tetramers include two __chains and two _____Chains

A

α chains

γ chains

63
Q

Besides pH in what way does CO2 decrease hemoglobin’s affinity for O2?

A

Carbon dioxide stabilizes deoxyhemoglobin by reacting with the terminal amino groups to form carbamate

64
Q

Enzyme important for the production of bicarbonate

A

carbonic anhydrase With (Zn) cofactor

65
Q

RBCs that are cycle type have decreased solubility from?

A

a valine residue for a glutamate residue in position 6 of β-globin. Decreases the solubility of deoxyhemoglobin,

66
Q

Smokers also ingest a lot of___ which competes with oxygen for binding to heme group.

A

CO

67
Q

What are the precursor molecules of purines?

A

Glycine
aspartic acid
glutamoine
CO2 and THF Coenzymes (Tetrahydrofolate)

68
Q

What are the precursor molecules of pyrimidines.

A

Aspartic acid, glutamine, CO2

69
Q

What is the basic structure of purines?

A

6 and 5 ring base

70
Q

What is the basic structure of pyrimidines?

A

one 6 ring base

71
Q

Metabolic precursors of De novo synthesis of nucleotides

A

amino acids, ribose 5-phosphate, CO2, and NH3

72
Q

Synthesis of _____________ from PRPP is first committed step in purine nucleotide biosynthesis (de novo) What is the enzyme?

A

5- phosphoribosylamine

Enzyme: PRPP amidotransferase

73
Q

where does De Novo Purine Nucleotide Biosynthesis occur?

A

Occurs primarily in liver but also in peripheral tissues.

74
Q

Biosynthetic precursors of De Novo Purine Nucleotide Biosynthesis.

A

Atoms used from glycine, aspartate glutamine, CO2 and tetrahydrofolate.

75
Q

Conversion of Nucleoside Monophosphates to Nucleoside Diphosphates is catalyzed by?

A

Adenylate kinase and guanylate kinase

76
Q

Conversion of Nucleoside Diphosphates to Nucleoside Triphosphate is catalyzed by

A

Nucleoside diphosphate kinase

77
Q

The “parent” molecule in both purine and pyrimidine biosynthesis…

A

a. Purine: Inosine monophosphate (IMP)

b. Pyrimidine: OMP

78
Q

The Pyrimidine de Novo pathway is Catalyzed by _______________, an enzyme distinguishable from CPS I in its cytosolic location and its use of the amide group of glutamine for its nitrogen source.

A

carbamoyl phosphate synthetase II

79
Q

De Novo Purine Nucleotide Biosynthesis

Rate limiting step and enzyme.

A

Synthesis of 5 phosphoribosylamine from PRPP

80
Q

Conversion of Ribonucleotides to Deoxyribonucleotides

Requires the enzyme ___________________.

Requires_________ as a reducing agent. (protein with SH groups that get oxidized).

To continue, the latter must be regenerated. ___________catalyzes reduction of the disulfide using NADPH.

A

Ribonucleotide reductase (RNR)

thioredoxin

Thioredoxin reductase

81
Q

Pyrimidine bases can be salvaged using enzyme ___________________ to form the respective nucleotides. However, this is not a significant route and very few pyrimidine bases are salvaged.

A

enzyme: pyrimidine phosphoribosyltransferase) using PRPP

82
Q

Name the 2 enzymes involved in purine base salvage.

A

A. Adenine phosphoribosyl transferase (APRT)

i. Adenine + PRPP SS> AMP + PPi

B. Hypoxanthine V Guanine phosphoribosyl transferase (HGPRT)

i. (Note dual substrate specificity)
ii. Hypoxanthine + PRPP SS> IMP + PPi
iii. Guanine + PRPP SS> GMP + PPi

83
Q

gout and the LeschSNyhan syndrome have an enzyme deficiency in common. What is the enzyme?

A

Hypoxanthine V Guanine phosphoribosyl transferase (HGPRT)

84
Q

Gout is characterized by__________.

A

hyperuricemia Build up of uric acid

85
Q

_________inhibits xanthine oxidase, resulting in an accumulation of hypoxanthine and xanthine compounds more soluble than uric acid.

A

Allopurinol

86
Q

the biological basis of Severe Combined Immunodeficiency disease (SCID)

A

SCIDs Adenosine Deaminase (ADA) deficiency

Involves TScell and BScell dysfunctions

Usually die young

87
Q

enzymes cannot make a fatty acid with a double bond more than ___ carbons from carboxyl end

A

enzymes cannot make a fatty acid with a double bond more than 9 carbons from carboxyl end

88
Q

Omega 6 – forms Arachadonic acid – Eicosanoids for inflammation

A

Linoleic Acid

89
Q

Omega 3 – forms Eicosanoids for ant inflammation

A

Linolenic Acid

90
Q

This is a class of compounds that exert hormone-like effects in many physiological processes

A

eicosanoids, such as prostaglandins.

91
Q

Enzyme only useful for short and medium chain fatty acids.

A

Gastric lipase (pH 7 optima)

92
Q

Bile acids are cholesterol derivatives that are synthesized by the liver and secreted as…

A

glycine or taurine conjugates.

93
Q

Most bile acids are reabsorbed in the small intestine, returned to the liver via the portal vein, and may be reSsecreted. Interrupting this cycle will lower cholesterol (medications, fiber, etc.)

A

Enterohypatic Cycle

94
Q

Released from jejunum in response to chyme in duodenum

  1. Stimulates gall bladder bile release
  2. Release of pancreatic digestive enzymes
  3. Slows down gastric emptying
A

Cholecystokinin

95
Q

i. Released in duodenum in response to the low pH of the chyme entering the intestine
ii. Induces pancreas to release a bicarbonate solution to neutralize the acidiic pH of the chyme
iii. Notably, the first “hormone” identified (1902)

A

Secretin

96
Q

converts TAGs into 2Smonoacylglycerol and free fatty acids

A

Pancreatic lipase

97
Q

Stabilizes pancreatic lipase at lipid water interface

A

Colipase

98
Q

Stabilize pancreatic lipase and in its formation, turns into
esterostatin to act as a satiety signal.

A

Colipase

99
Q

degrades cholesterol esters to free fatty acids and cholesterol.

A

Cholesterol (sterol)esterase

100
Q

Removes the fatty acid
at C2 leaving a lysophospholipid.

The remaining fatty acid at C1 can be removed by_______________, leaving a glycerylphosphorylbase

A

Phospholipase A 2

lysophospholipase

101
Q

Intracellular fatty acids are sequestered by being bound with ____________.

(Takes fat and keeps in one area so that it cannot be disruptive)

A

Fatty acid binding protein 2

AKA
ntestinal-type fatty acid-binding protein (I-FABP)

1-FABP/FABP-2

102
Q

Chylomicrons receive Apo ___ and Apo ___ in circulation from _________.

A

Apo C-II
Apo E
HDL

103
Q

Fatty acids trapped in cells by conversion to fatty acylSCoA thioesters catalyzed by ___________.

A

fatty acyl CoA synthetase

note: 2 ATP equivalents used

104
Q

rate limiting step of cholesterol synthesis

A

HMG Co A reductase

105
Q

CM triacylglycerol is distribution

A

80% adipose, heart, muscle 20% liver

106
Q

Promotes lipoprotein lipase activity

A

Apo C-II

107
Q

Reservoir for Apo C-II and Apo E for VLDLs

and chylomicrons

A

HDL provides Apolipoproteins

108
Q

A-1, activates LCAT (Lecithin-Cholesterol Acyl Transferase) also known as PCAT (phosphatidyl choline acyl transferase)) which catalyzes synthesis of cholesteryl esters using fatty acids cleaved from the membrane lipid lecithin.

A

Other Function of HDLs

109
Q

Breaks triacylglycerols into free fatty acids that will travel through the blood via albumin.

A

Hormone Sensitive Lipase (stimulated by Glucagon through Phosphorylation)

110
Q

CPT1 is Inhibited by…

A

Malonyl CoA (substrate for fat synthesis)

111
Q

committed step to fatty acid synthesis

A

The carboxylation of Acetyl-CoA(2C) by acetyl-CoA carboxylase to form Malonyl-CoA(3C)

112
Q

Acetyl CoA Carboxylase is inhibited by

A

Glucagon will phosphorylate this enzyme and inactivate it

113
Q

The synthesis of one palmitate molecule requires__ molecules of acetyl-CoA, __ATP and___ NADPH

A

8 acetyl-CoA
7 ATP
14 NADPH

ASDOH Metabolism (2 decks)

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