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Biochem Flashcards

1
Q

Histones are rich in what two amino acids?

A

Lysine and argenine (makes them positively charged)

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2
Q

Which is the only histone not found in the nucleosome core?

A

H1

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3
Q

Which histones make up the nucleosome core?

A

H2A, H2B, H3, H4 (each x2)

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4
Q

How does histone methylation affect gene transcription?

A

Methylation represses DNA transcription

“Methylation Mutes DNA”

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5
Q

How does Histone Acetylation affect gene transcription?

A

“Acetylation Activates DNA”

Relaxes DNA coiling, allowing for transcription

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6
Q

How does Leflunomide inhibit Pyrimidine base synthesis?

A

Inhibition of Dihydroorotate DH, which is responsible for the conversion of Carbamoyl phosphate into Orotic acid

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7
Q

How does Hydroxyurea inhibit pyrimidine base synthesis?

A

Inhibition of Ribonucleotide reductase, which is responsible for the conversion of UDP into dUDP

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8
Q

How does Methotrexate inhibit pyrimidine synthesis?

A

Inhibition of Dihydrofolate Reductase, which reduces DHF into THF

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9
Q

How does Trimethoprim (TMP) inhibit pyrimidine synthesis?

A

Inhibition of Dihydrofolate Reductase, which reduces DHF into THF

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10
Q

How does Pyrimethamine inhibit pyrimidine synthesis?

A

Inhibition of Dihydrofolate Reductase, which reduces DHF into THF

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11
Q

How does 5-Flourouracil (5-FU) inhibit pyrimidine synthesis?

A

Inhibition of Thymidylate sythase, which converts dUMP into dTMP

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12
Q

What is the RLS for pyrimidine synthesis?

A

Carbamoyl phosphate synthetase II

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13
Q

What is the precursor for 6-Mercaptopurine?

A

Azathioprine

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14
Q

What does 6-MP inhibit?

A

Purine base synthesis (PRPP–>IMP)

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15
Q

How does Mycophenolate inhibit purine base synthesis?

A

Inhibition of IMP DH

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16
Q

How does Ribavirin inhibit purine synthesis?

A

Inhibition of IMP DH

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17
Q

Deamination of which base gives uracil?

A

Cytosine

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18
Q

Why would a molecule with greater GC:AT ratio have a higher melting point?

A

G&C connect with 3 H bonds, A&T connect with 2 H bonds

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19
Q

What 5 substances are required to make a purine?

A

Glycine, Aspartate, Glutamine (GAG)

Tetrahydrofolate, CO2

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20
Q

What substances are required to make a pyrimidine?

A

Aspartate, Carbamoyl phosphate (glutamine+ATP+CO2)

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21
Q

Ribonucleotide reductase is an enzyme involved in the synthesis of what? What drug inhibits it?

A

Pyrimidine synthesis, Hydroxyurea

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22
Q

Thymidylate synthase is an enzyme involved in the synthesis of what? What drug inhibits it?

A

Pyrimidine synthesis, 5-FU

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23
Q

Dihydrofolate reductase is an enzyme used for the synthesis of what? What drugs inhibit it?

A

Pyrimidine synthesis; Methotrexate, Trimethoprim, Pyrimethamine

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24
Q

Orotic aciduria is caused by a mutation in what enzyme?

Pt has high orotic acid and ammonium levels

A

UMP synthase

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25
Which GLUT receptors require insulin for glucose uptake and where are they found?
GLUT-4 | -Skeletal muscle, Adipose tissue
26
Which GLUT transporter is responsible for fructose uptake in the GI tract?
GLUT-5
27
RLS of Glycolysis
PFK-1
28
RLS of Gluconeogenesis
Fructose 1,6 bisphosphate
29
RLS of TCA cycle
Isocitrate DH
30
RLS of Glycogenesis
Gycogen synthase
31
RLS of Glycogenolysis
Glycogen phosphorylase
32
RLS of HMP shunt
Glucose-6-phosphate DH (G6PD)
33
RLS of de novo Pyrimidine synthesis
Carbamoyl Phosphate Synthetase II
34
RLS of De novo Purine synthesis
Glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase
35
RLS of Urea cycle
Carbamoyl Phosphate Synthetase I
36
RLS of fatty acid synthesis
Acetyl-CoA carboxylase (ACC)
37
RLS of fatty acid oxidation?
Carnitine acyltransferase I
38
RLS of Ketogenesis
HMG-CoA synthase
39
RLS of Cholesterol synthesis
HMG-CoA reductase
40
Pt with painful muscle cramps, myoglobinuria (red urine) with strenuous exercise and arrhythmia from electrolyte abnormalities
McArdle Dz (glycogen storage dz type V) - Deficiency of Glycogen phosphorylase in muscle cells - Can't break down glycogen's alpha 1,4 bonds
41
What enzyme is deficient in McArdle dz?
Glycogen phosphorylase (breaks down alpha 1,4 bonds)
42
Severe fasting hypoglycemia, elevated lactate in blood, hepatomegaly. Liver biopsy shows elevated glycogen in the liver cells
Von Gierke dz (glycogen storage dz Type I) | -Deficiency in Glucose-6-phosphatase (G6P=>glucose)
43
What is the enzyme deficient in Von Gierke dz?
Glucose-6-phosphatase
44
Milder form of type I glycogen storage dz with normal lactate
``` Cori dz (Type III) -lack of debranching enzyme (alpha1-6 bonds) ```
45
Glycogen storage dz leading to cardiomyopathy and early death
``` Pompe dz (type II) -Lack of lysosomal alpha-1-4-glucosidase ```
46
RLS of glycogen synthesis?
Glycogen synthase
47
RLS for glycogenolysis?
Glycogen phophorylase
48
What enzyme converts glucose-6-phosphate to glucose?
Glucose-6 phosphatase
49
Glycogen phosphorylase deficiency
McArdle dz
50
Glucose-6-phosphatase deficiency
Von Gierke dz
51
Lactic acidosis, hyperlipidemia, hyperuricemia (gout)
Von Gierke dz
52
Alpha 1,6 glucosidase deficiency (debranching enzyme)
Cori dz
53
Alpha 1,4 glucosidase deficiency
Pompe dz
54
Cardiomegaly
Pompe dz (infantile)
55
Diaphragm weakness leading to respiratory failure
Pompe dz (adult)
56
Increased glycogen in liver, severe fasting hypoglycemia
Von Gierke dz
57
Hepatomegaly, hypoglycemia, hyperlipidemia (normal kidneys, lactate and uric acid)
Cori dz
58
Painful muscle cramps, myoglobinuria with strenuous exercise
McArdle dz
59
Severe hepatosplenomegaly, enlarged kidneys
Von Gierke dz
60
What's the RLS of the HMP shunt (pentose-phosphate) pathway?
Glucose-6-phosphate Dehydrogenase (G6PD)
61
What is G6PD usually used for?
Generation of NADPH
62
How does a deficiency of G6PD result in hemolytic anemia?
G6PD generates NADPH which is used by Glutathione Reductase to reduce Glutathione (GSH). Glutathione is used by Glutathione peroxidase to detoxify free radicals and peroxides. Without G6PD, RBC are highly susceptible to oxidative damage and will lyse in response to oxidative stress
63
What enzyme is deficient in classic galactosemia?
Galactose-1P Uridyltransferase | -failure to thrive, cataracts, hepatomegaly, jaundice, mental retardation
64
Deficiency of Galactokinase
Galactokinase deficiency (feygit)
65
Deficiency of Aldolase B
Fructose intolerance
66
Deficiency of lactase
Lactose intolerance
67
Deficiency of Galactose-1P Uridyltransferase deficiency
Classic Galactosemia
68
Deficiency of Fructokinase
Essential fructosuria
69
What is Apo B-48 used for?
Chylomicron secretion from enterocyte to lymphatic system
70
What is Apo B-100 used for?
Liver packages VLDL with Apo B-100 for excretion into system (so cells can pull FFA off of it) -Apo B-100 found on VLDL, IDL, LDL
71
What is the purpose of Apo E?
Mediates extra remnant uptake
72
What's the purpose of Apo A-1?
Found on HDL, Activates LCAT (puts cholesterol from tissue cells onto HDL)
73
What's the purpose of Apo C-II?
Cofactor for Lipoprotein lipase (LPL) | -LPL pulls FFA off of chylomicrons and VLDL and puts it into tissue
74
What is the RLS for cholesterol synthesis?
HMG-CoA reductase
75
What is cholesterol made from in the liver?
Acetyl-CoA
76
What is the RLS for Ketone synthesis?
HMG-CoA Synthase
77
What is the RLS for Fatty acid synthesis?
Acetyl-CoA Carboxylase | -FA synthesis occurs in the cytoplasm
78
What is the RLS for FA degradation?
Carnitine acyltransferase-1 (carnitine palmitoyl transferase 1)
79
What deficiency causes familial hypercholesterolemia?
LDL receptor deficiency
80
Activates LCAT
Apo A1
81
Mediates Chylomicron secretion
Apo B48
82
Binds to LDL receptor
Apo B100
83
Cofactor for lipoprotein lipase
Apo CII
84
Mediates uptake of remnant particles
Apo E
85
Mediates VLDL secretion
Apo B100
86
What are the essential amino acids?
``` "PVT TIM HaLL" Phenylalanine Valine Threonine Tryptophan Isoleucine Methionine Histidine Leucine Lysine ```
87
Classic basic AAs
Lysine, argenine (both have an extra ammonia group) | Histidine
88
Which of the basic AAs are found in high concentrations in histones?
Argenine and Lysine | -Their positive charges allow for interaction with (-) DNA
89
Acidic AAs
Aspartate, Glutamate (Aspartic acid, glutamic acid) | (-) charge at body pH
90
What's the AA precursor for Epinephrine?
Phe=>Tyrosine=>DOPA=>Dopamine=>NE=>Epi
91
What amino acids build up in Maple Syrup urine dz?
``` "I LoVe maple syrup" Isoleucine Leucine Valine (Branched chain AAs) ```
92
What enzyme is deficient in Maple syrup urine dz?
alpha Ketoacid DH

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