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biochem exam 3 Flashcards

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1
Q

_____ are organic molecules that are characterized by low solubility in water, and are relatively hydrophobic

A

lipids

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2
Q

how many carbons does carboxylic acids with hydrocarbon chains contain?

A

4 - 36 carbons

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3
Q

almost all natural fatty acids are ________ and have an _______ number of carbons

A

unbranched; even

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4
Q

what is it called when there are no double bonds between carbons in the FA chain?

A

saturated

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5
Q

what it is called when theres one double bond between carbons in the alkyl chain?

A

monounsaturated

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6
Q

what is it called when theres more than one double bond in the alkyl chain?

A

polyunsaturated

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7
Q

solubility of fatty acids _________ as the chain length _________

A

decreases; increases

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8
Q

melting point of fatty acids _________ as the chain length __________

A

decreases; decreases

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9
Q

melting point of fatty acids _________ as the number of double bonds _________

A

decreases; increases

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10
Q

enzymatic oxidation of ________ yields prostaglandins eicosanoids, thromboxanes eicosanoids, and leukotrienes

A

arachidonic acid

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11
Q

what process yields prostaglandins eicosanoids, thromboxanes eicosanoids, and leukotrienes?

A

enzymatic oxidation of arachidonic acid

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12
Q

vitamin D regulates what?

A

calcium uptake

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13
Q

vitamin A is also known as

A

Retinol

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14
Q

which vitamins act as antioxidants?

A

vitamin E, K, and other lipid quinones

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15
Q

whats the precursor for both triacylglycerols and glycerophospholipids?

A

phosphatidic acid

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16
Q

_____________ removes the 3-phosphate from the phosphatidic acid

A

phosphatidic acid phosphatase (lipin)

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17
Q

the first step of cholesterol synthesis is….

A

three acetate condense to form mevalonate

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18
Q

the second step of cholesterol synthesis is…

A

mevalonate converts to phosphorylated 5-C isoprene

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19
Q

the third step of cholesterol synthesis is…

A

six isoprenes polymerize to form the 30-C linear squalene

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20
Q

the fourth step of cholesterol synthesis is…

A

squalene cyclizes to form the four rings that are modified to produce cholesterol

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21
Q

what sequence is likely to be the consensus sequence of myristoylation motif?

A

MGXXS

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22
Q

an integral membrane protein can be extracted with…?

A

a solution containing detergent

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23
Q

which of the following is not an intermediate in the synthesis of lanosterol from acetyl-CoA

A

Malonyl-CoA

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24
Q

more fluid membranes require ______ and more ________ fatty acids

A

shorter; unsaturated

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25
at higher temperatures, cells need more of what?
saturated fatty acids
26
at lower temperatures, cells need more of what?
unsaturated fatty acids
27
cystic fibrosis is caused by a mutation to an ion channel in what kinds of cells?
epithelial cells
28
all amino acids derive from what...?
one of seven precursors
29
what precursor(s) does pentose phosphate pathway derive from?
ribose 5-phosphate
30
what precursor(s) does glycolysis derive from?
pruvate, 3-phosphoglycerate, phosphoenolpyruvate, erythrose 4-phosphate
31
what precursor(s) does CAC derive from?
α-ketoglutarate, oxaloacetate
32
who can synthesize proline from arginine?
animals
33
is this correct? Arg --> ornithine (+ Ornithine δ-aminotransferase) --> glutamate γ-semialdehyde --> Pro
yes it is!
34
Glutathione (GSH) derives from what?
Glu, Cys, and Gly
35
what is GSH?
reducing agent/ antioxidant - oxidized to a dimer (GSSG)
36
what is lignin?
rigid polymer in plants
37
what is auxin?
growth hormone indole-3-acetate
38
what amino acids are precursors for lignin?
Phe and Tyr
39
what amino acids are precursors for auxin?
Trp
40
Histadine yields the vasodilator and stomach acid secretion stimulant __________
Histamine
41
Glu yields neurotransmitters ___________ and _________
γ-aminobutyrate (GABA); serotonin
42
Tyrosine yields catecholamines such as ...?
dopamine, norepinephrine, and epinephrine
43
which amino acid is involved in the immune and inflammatory response
histamine
44
synthesized from Arg via nitric oxide synthase using _______
NADPH
45
name the major endocrine glands
hypothalamus, pituitary, thyroid, parathyroids, adipose tissue, adrenals, pancreas, ovaries, testes
46
second messengers are ...?
intracellular signaling molecules released by the cell to trigger physiological change
47
biosynthesis of thymidylate (dTMP) begins with the reaction catalyzed by...?
ribonucleotide reductase
48
____________ deficiency leads to reduced thymidylate synthesis
folic acid
49
removing what from the DNA will create strand breaks that are associated with cancer, heart disease, etc...
uracil
50
what is required for regeneration of the N5,N10-methylene form of tetrahydrofolate?
serine hydroxymethyltransferase
51
gout is caused by
deposits of sodium urate crystals in joints
52
gout is treated with avoidance of what?
purine rich foods or fructose
53
second hand way of treating gout is by taking the xanthine oxidase inhibitor _______
allopurinol
54
which enzyme would produce cAMP?
adenylate cyclase
55
what are G-protein Coupled Receptors (GPCRs)?
α-helical intergral membrane proteins
56
epinephrine is also known as...
the fight or flight hormone
57
epinephrine binding to receptors in muscle or liver cells induces __________
breakdown of glycogen
58
epinephrine binding to receptors in adipose cells induces ________
lipid hydrolysis
59
epinephrine binding to receptors in heart cells ___________
increases heart rate
60
what is a substance that initiates a physiological response when combined with a receptor
agonist
61
what is a chemical that acts within the body to reduce the physiological activity of another chemical substance?
antagonist
62
what toxins act to constantly activate adenylate cyclase, producing too much cAMP from ATP?
cholera toxin and pertussis toxin
63
calcium modulates the function of many enzymes through _________
calmodulin
64
what is the abbreviation for calmodulin?
calcium-modulated protein
65
what is calmodulin?
a calcium-binding messenger protein expressed in all eukaryotic cells
66
insulin is synthesized on ribosome of β-cells as...
preproinsulin
67
insulin is what kind of hormone?
peptide hormone
68
peptide hormone insulin is secreted in response to what?
increased blood glucose levels
69
adipocytes are
lipocytes and fat cells
70
1,25-dihydroxyvitamin D3 is also known as
vitamin D
71
insulin stimulate glucose uptake in __________
muscle and fat
72
in the liver, insulin stimulates _________
glycogen synthase
73
glycogen synthase in the liver inactivates what?
glycogen phosphorylase
74
insulin stimulates _________ in muscle and fat
glucose uptake
75
which vitamin affects transcription of genes that regulates Ca2+ & the balance between Ca2+ deposition and removal from bone
vitamin D
76
what is the rate limiting step AND point of regulation in the formation of mevalonate from acetyl-CoA?
HMG-CoA + 2 NADPH --> mevalonate (catalyzed by HMG-CoA reductase)
77
what is the target for some cardiovascular drugs?
HMG-CoA reductase
78
statins are...?
HMG-CoA reductase inhibitors - cholesterol lowering drugs and lowers the risk of developing cardiovascular disease
79
HMG-CoA reductase is most active when __________
dephosphorylated
80
galactolipids: abundant or absent in plants & animals?
plants --> abundant in chloroplasts animals --> absent
81
lipid composition of membranes is different in...
various organisms, tissues, and organelles
82
plants and bacteria can biosynthesize what amino acid to what amino acid?
Cys --> Ser
83
what is the reaction (2 acetyl-CoAs --> acetyoacetyl-CoA) catalyzed by?
acetyl-CoA acyl transferase
84
HMG-CoA + 2 NADPH --> ?
mevalonate
85
what is the reaction (HMG-CoA + 2 NADPH --> mevalonate) catalyzed by?
HMG-CoA reductase - rate limiting step and point of regulation!!
86
what is the reaction (Acetyl-CoA + Acetoacetyl-CoA  β-hydroxyl-β-methylglutaryl-CoA (HMG-CoA)) catalyzed by?
HMG-CoA synthase
87

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