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STEP1 2015 > BIOCHEM > Flashcards

BIOCHEM Flashcards

(111 cards)

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1
Q

5 substances required for purine synthesis

A

tetrahydrofolate, HCO3 > Co2,
glutamine
aspartate
glycine

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2
Q

nucleotide versus nucleoside

A

nucleotide is phosphorylated

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3
Q

4 substances required to make pyrimidines

A

aspartate
CO2
glutamine
ATP

CO2, ATP, and glutamine go into carbamoyl phosphate (requires energy)

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4
Q

Carbamoyl phosphate synthetase 2

A

rate limiting step of pyrimidine synthesis, which makes carbamoyl phosphate

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5
Q

CPS1

A

urea cycle, mitochondria, n from ammonia

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6
Q

CPS2

A

pyrimidine synthesis, cytosol, n from glutamine

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7
Q

deficiency of UMP synthase of pyrimidine synthesis pathway

A

orotic aciduria
AR
increased orotic acid in urine
uncommon cause of megaloblastic anemia that cannot be corrected with B12 of folic acid supplements
does not cause hyperammonemia (unlike ornithine transcarbamylase deficiency of urea cycle)

Tx: supplement uridine

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8
Q

purines can be salvaged rather than made de novo

A

GMP to guanosine to guanine to xanthine to uric acid

IMP to inosine to hyoxanthine to xanthine to uric acid

AMP to adenosine to inosine to hypoxanthine to xanthine to uric acid

HGPRT is a phosphoribosyltransgerase that converts guanine and inosine back to GMP and IMP respectively

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9
Q

Lesch- Nyhan

A 
deficient HGPRT
gout
intellectual disability
aggressive behavior
self- mutilation- lip biting
movement disorders- dystonia
x- linked

Tx: allopurinol, febuxostat to prevent formation of uric acid

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10
Q

Adenosine deaminase deificiency

A

SCID

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11
Q

rate limiting enzyme in purine synthesis

A

glutamine PRPP amidotransferase

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12
Q

sources of carbon in purine synthesis

A

CO2, glycine, tetrahydrofolate

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13
Q

sources of nitrogen in purine synth

A

glycine, aspartate and glutamine (GAG)

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14
Q

carbon in pyrimidine synthesis

A

HCO3, aspartate

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15
Q

nitrogen in pyrimidine synth

A

glutamine

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16
Q

inhibits ribonucleotide reductase

A

hydroxyurea

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17
Q

inhibits dihydrofolate reductase

A

methotrexate, trimethoprim

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18
Q

inhbits thymidylate synthase

A

5FU

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19
Q

inhibits inosine monophosphate dehydrogenase

A

mycophenolate

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20
Q

inhibits PRPP amidotransferase

A

6 mercaptopurine

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21
Q

aa’s accounting for positive charge in histones

A

lysine and arginine

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22
Q

Southern blot

A

DNA probe, DNA sample

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23
Q

Northern blot

A

DNA probe, RNA sample

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24
Q

Western blot

A

ab probe, protein sample

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25
SW blot
DNA- binding protein sample, Oligonucleotide probe
26
ELISA | enzyme-linked immunosorbent assay
direct: tests for ag in patient's blood abs on the well, add ample to see if it contains antigen then add antibodies to illuminate (sandwich) Indirect ELISA: tests for antibodies in the patient's blood wells coated with ag. abs from pt sample bind the well add signal antibodies that bind the antibodies
27
FISH
known segment of DNA hybridize with fluorescent DNA or RNA probe fluorescence indicates that the gene is present If absent, the gene has been deleted
28
knock-in constitutive insertion
gene randomly inserted
29
knock-in conditional insertion
targeted insertion
30
karyotyping
metaphase chromosomes, paired stain the bands are there obvious changes in the chromosome?
31
rate limiting enzyme in de novo pyrimidine synthesis
CPS2
32
rate limiting enzyme in de novo purine synthesis
glutamine PRPP amidotransferase
33
rate limiting enzyme in glycolysis
PFK1
34
rate limiting enzyme in gluconeogenesis
fructose 1,6 bisphosphatase
35
rate limiting enzyme in glycogen synthesis
glycogen synthase
36
rate limiting enzyme in glycogenolysis
glycogen phosphorylase
37
rate limiting enzyme in TCA cycle
isocitrate dehydrogenase
38
rate limiting enzyme in hexose monophosphate shunt
glucose 6 phosphate dehydrogenase (G6PD)
39
gibbs free energy
Delta G= Delta H- T*DeltaS Gibbs free energy= change in enthalpy minus Temperature times change in Entropy
40
glycogen phosphorylase deficiency in skeletal muscle (myophosphorylase)
McArdle disease
41
Glucose-6-phosphatase deficiency
von Gierke disease
42
increased glycogen storage, lactic acidosis, hyperlipidemia, hyperuricemia (gout), glucose 6 phosphatase deficiency, affecting liver and kidney, leading to severe hypoglycemia, progressive renal disease, growth retardation, delayed puberty
von Gierke disease
43
alpha 1-6 glucosidase deficiency
Cori disease
44
alpha 1-4 glucosidase deficiency in lysosomes
Pompe disease infantile- cardiomegaly, infantile onset, less than one year life expectancy adult- diaphragm weakness leading to respiratory failure
45
increased glycogen in liver, severe fasting hypoglycemia
von Gierke disease
46
hepatomeglay, hypoglycemia, hyperlipidemia (normal kidneys, lactate, uric acid)
Cori disease
47
painful muscle cramps, myoglobinuria with strenuous exercise
McArdle disease
48
severe hepatosplenomegaly, enlarged kidneys
von gierke disease
49
vitamin deficiency resulting from Hartnup disease
lack of tryptophan leads to niacin deficiency, leading to pellagra
50
TLC For Nobody
``` pyruvate dehydrogenase complex cofactors 1. pyrophosphate (B1, thiamine) 2. FAD (B2, riboflavin) 3. NAD (B3, niacin) 4, CoA (B5, pantothenic acid) 5. Lipoic acid ```
51
GI problems (vomiting, rice- water stools) plus garlic breath , and blocked lipoic acid
arsenic poisoning, leading to pyruvate dehydrogenase deficiency (lactic acidosis, neurological defects)
52
what 4 end products can be made from pyruvate
OAA, Acetyl CoA, alanine, lactate
53
Galactokinase deficiency
galactitol accumulates (via aldose reductase), relatively mild, AR, infantile cataracts, failure to track objects or develop social smile
54
Aldolase B deficiency
AR, fructose-1-phosphate accumulates with a decrease in available phosphate, resulting in inhibition of glycogenolysis and gluconeogenesis. Sx: hypoglycemia, jaundice, cirrhosis, vomiting. Treatment: reduce fructose and sucrose intake.
55
sucrose
glucose and fructose
56
lactose
galactose and glucose
57
galactose-1-phosphate uridyltransferase deficiency
Classic galactosemia. AR, accumulation of galactitol. | Sx: FTT
58
FAB GUT
fructose is to Aldolase B as Galactose is to UridylTransferase The more serious defects lead to PO43- depletion
59
fructokinase deficiency
essential fructosuria
60
pancreatic insufficiency- symptoms
``` diarrhea steatorrhea malabsorption weightloss ADEK fat- soluble vitamin deficiency ```
61
serotonin syndrome
muscle rigidity, hyperthermia, CV collapse due to autonomic instability
62
chylomicrons
deliver Tgs to peripheral tissue, deliver cholesterol to liver
63
VLDL
deliver TGs to peripheral tissue
64
IDL
deliver TGs and cholesterol to liver
65
ApoB48
chylomicron secretion from enterocyte to lymphatic system
66
ApoB100
found on VLDL, IDL, LDL | binds LDL receptor
67
ApoE
mediates extra remnant uptake
68
ApoA1
activates LCAT, found on HDL HDLs help scoop up extra cholesteral by moving it from cells to fat particles
69
ApoCII
cofactor for lipoprotein lipase
70
Abetalipoproteinemia
AR defective ApoB48 and ApoB100 without these lipoproteins, enterocytes are never getting rid of their chylomicrons 2/2 mutation in microsomal transfer protein (MTP) as a result there is decreased chylomicron and VLDL synthesis and secretion. presents in the first few months of life, with steatorrhea (ADEK) on intestinal biopsy, the enterocytes will be swollen with TGs you will also see acanthocytosis of RBCs on peripheral smear (plasma membrane looks spiky due to altered membrane lipids) Sx: ataxia, night blindness (no VitA) Treat with Vit E which helps to restore the lipoproteins
71
Type I hyperchylomicronemia
AR, lipoprotein lipase deficiency or defective ApoCII (cofactor for lipoprotein lipase) in the blood you will find increased chylomicrons, TGs, cholesterol presents with pancreatitis 2/2 increased TG, hepatosplenomegaly, pruritic xanthomas no increased risk for atherosclerosis
72
Type IIA familial hypercholesterolemia
AD, with absent of decreased LDL receptors, resulting in increased LDL in blood tedinous xanthomas corneal arcus accelerated atherosclerosis myocardial infarction
73
type IV hypertriglyceridemia
AD. overproduction of VLDL in the liver pancreatitis
74
where does cholesterol come from?
Acetyl CoA
75
What is the rate limiting enzyme in cholesterol synthesis
HMG-CoA reductase (as opposed to synthase which is involved in ketone synthesis)
76
what drugs inhibit HMG CoA reductase
statins
77
where does fatty acid synthesis take place
cytoplasm of hepatocytes
78
what is the precursor molecule for fatty acids?
acetyl coA
79
what is the rate limiting enzyme for fatty acid synthesis
acetyl- coA carboxylase
80
where does fatty acid degradation occur?
mitochondria
81
what is the rate-limiting enzyme in fatty acid degredation?
carnitine acyltransferase 1 (Carnitine palmityoltransferase 1)
82
what happens if you don't have CAT1?
unable to transport LCFAs to mitochondria accumulation of LCFAs in cytoplasm presentation: weakness, hypotonia, hypoketotic hypoglycemia
83
rate limiting enzyme for ketone body synthesis
HMG-CoA synthase
84
rate-limiting enzyme for cholesterol synthesis
HMG- CoA reductase
85
Where is excess iron stored (after hemaglobin and myoglobin are satisfied)
liver, spleen, bone marrow
86
ABG change 6-72 hrs into iron OD
metabolic acidosis
87
Ferritin
iron protein complex (ferric acid and apoferritin) cellular storage protein for iron acute phase reactant
88
Transferrin (transport)
protein that binds ferric molecules and transports them through plasma. synthesized in the liver. Half- life of 8 days Transferrin increased in iron deficiency when cells are hungry for iron
89
zinc functions
zinc finger motif, important in healing, during transcription. important in healing, immune system, carbonic anhydrase. lactate dehydrogenase also requres zinc
90
zinc deficiency
delayed wound healing, decreased body and facial hair, hypogonadism, anosmia, dysgeusia decreased immune response rash around eyes, mouth, nose anus (acrodermatitis enteropathica) ``` anorexia and diarrhea growth retardation decreased mental function impaired night vision infertility ```
91
lead poisoning
inhibited ferrochelatase and ALA dehydratase lead to decreased heme synthesis and increased RBC protoporphyrin basophilic stippling (rRNA retainged in RBCs) ringed sideroblasts (RBC precursors) in bone marrow anemia abd pain neuropathy leading to wrist and goot drop Burton lines on gingivae encephalopathy, drop in IQ succimer or EDTA if severe, use dimercaprol and succimer
92
mercury poisoning
accumulates in kidney and brain enlarged kidneys, neuro symptoms acrodynia: peeling of the fingertips abdominal pain common sources: shark, swardfish, tilefish, king mackeral, old thermometers, batteries
93
hypocalcemia
tetany and neuromuscular irritability Chvostek sign (tap the cheek) Trousseau (tighten blood pressure cuff)
94
Common causes of ARDS
``` shock infection toxic gas inhalation acute pancreatitis aspiration heroin overdose high concentrations of O2 ```
95
Vitamin K role in clotting factor formation
cofactor for gamma carboxylation of glutamic acid residues on various proteins required for blood clotting. (2, 7, 9. 10, C, S)
96
drugs that lead to Vit K deficiency
warfarin, phenytoin, antibiotics that wipe out gut flora
97
What vitamin B deficiency causes seizures, irritability
B6, which is involved in producing GABA
98
vitamins involved in megaloblastic anemia
B12, folate
99
where is B12 absorbed in the gut
terminal ileum
100
Which vitamin deficiency is associated with peripheral neuropathy, glossitis?
B12, B6
101
Which vitamin deficiency is associated with NTD?
folic acid
102
Which vitamin deficiency is associated with dermatitis, diarrhea, dementia
B3 (niacin), pellagra
103
Which vitamin deficiency is associated with megaloblastic anemia
folic acid, B12
104
Which vitamin deficiency is associated with pernicious anemia
B12
105
Which vitamin is used in redox reactions
B2 (riboflavin FMN FAD), B3 (niacin) NAD, NADP
106
Which vitamin is used in carboxylation reactions
B7 biotin (gamma glutamate carboxylation)
107
Which vitamin requires IF for absorption
B12
108
Which vitamin is used by pyruvate dehydrogenase in alpha KG
B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (CoA, pantothenic acid), lipoic acid
109
deficiency can be 2/2 INH use
B6, B3
110
Cobalt is found within this vitamin
B12 (cobalamin)
111
Critical for DNA synthesis
folate, B12

STEP1 2015 (30 decks)

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