Biochemistry - Qbook

Front 1

what catalyzes the irreversible conversion of pyruvate to acetyl CoA?

Back 1

pyruvate dehydrogenase

Front 2

if pyruvate dehydrogenase is absent, what will it be converted to?

Back 2

alanine via alanine aminotransferase;
lactate via lactate dehydrogenase

Front 3

what is the porphyrin ring of heme derived from?

Back 3

TCA cycle intermediate succinyl-CoA and AA glycine; this initial synthetic step, which is rate-limiting, is catalyzed by aminolevulinic acid synthase

Front 4

vitamin K is an important coenzyme for what?

Back 4

gamma-gluyamylcarboxylase, an enzyme that catalyzes a post-translational modification of a group of calcium-binding proteins

Front 5

how does vitamin K deficiency manifest in infants?

Back 5

GI bleeding, skin hemorrhages, intracranial hemorrhage
late-onset vitamin K bleeding can occur between 1-6 months after birth - risk factors include exclusive breast feeding because human milk is low in vitamin K

Front 6

absence of vitamin B12 results in the accumulation of what?

Back 6

methylmalonyl-CoA (B12 is a cofactor in the conversion of methylmalonyl-CoA to succinyl-CoA)

Front 7

what is the clinical picture associated with galactokinase deficiency?

Back 7

very mild disease - only significant complication is cataract formation

Front 8

what does homozygous deficiency of galactose-1-phosphate uridyltransferase lead to?

Back 8

severe disease, culminating in death in infancy: impaired renal tubular absorption leading to aminoaciduria, GI symptoms, hepatosplenomegaly, cataracts, bleeding diatheses, hypoglycemia, and MR

Front 9

what is the process of glycolysis?

Back 9

converts glucose into pyruvate with concomitant production of ATP

Front 10

name three ketone bodies

Back 10

acetoacetate, beta-hydroxybutyrate, and acetone

Front 11

when/how are ketone bodies produced?

Back 11

produced by liver in the fasting state by beta-oxidation of fatty acids

Front 12

this condition is associated wth MR, hepatosplenomegaly, foam cells in bone marrow, cherry red spots, and neuro deficits - death by 3 years of age is common

Back 12

Niemann-Pick

Front 13

what is the mechanism of cipro?

Back 13

inhibits DNA gyrase (prokaryotic topoisomerase II) essential for DNA replication

Front 14

what is the mechanism of statins?

Back 14

HMG-CoA reductase inhibitors

Front 15

this syndrome is characterized by MR, nervous system malformations, rocker-bottom feet, polydactyly, and cleft lip and palate

Back 15

Trisomy 13/Patau syndrome

Front 16

where does the clinically important degradation of ethanol to acetaldehyde occur in humans?

Back 16

peroxisomes and SER (P450)

Front 17

where is acetaldehyde oxidized to acetate?

Back 17

mitochondria

Front 18

what is the defect in von Gierke's?

Back 18

glucose-6-phosphatase

Front 19

what is Smith-Lemli-Opitz syndrome?

Back 19

recessive genetic disease - first single-gene disease to be associated with multiple malformations

Front 20

microcephaly, MR, hypotonia, incomplete development of genitalia, high forehead, pyloric stenosis, syndactyly of 2nd and 3rd toes are characteristic of what syndrome?

Back 20

Smith-Lemli-Opitz

Front 21

what technique is used to identify a specific protein that may be present in very small concentrations in a complex protein mixture?

Back 21

Western blotting

Front 22

what technique utilizes DNA-RNA hybridization to determine the size and abundance of RNA for a specific gene?

Back 22

Northern blotting

Front 23

what technique utilizes DNA-DNA hybridization?

Back 23

Southern blotting

Front 24

what technique involves DNA-protein interactions?

Back 24

Southwestern blotting - a protein sample is subjected to electrophoresis, transferred to a filter, and exposed to labeled DNA

Front 25

following treatment of ALL, patients often have a high level of what? how do you treat them?

Back 25

urate (secondary to breakdown of nucleic acids) - Rx: allopurinol to decrease plasma urate levels (inhibition of xanthine oxidase)

Front 26

what is the best technique for determining whether a gene is expresed in a particular cell type?

Back 26

Northern blot

Front 27

what is the most common technique used to screen for cystic fibrosis?

Back 27

PCR

Front 28

what is the primary source of ketones in diabetic ketoacidosis?

Back 28

free fatty acid breakdown

Front 29

severe neonatal jaundice, elevated indirect bilirubin, and exchange blood transfusion suggest what?

Back 29

hemolysis

Front 30

increased levels of 2,3 BPG, 3-PG, 2-PG, and PEP correspond with what type of hemolytic anemia?

Back 30

one induced by pyruvate kinase deficiency

Front 31

perifollicular hemorrhages, fragmentation of hairs, purpura, ecchymoses, splinter hemorrhages, and hemorrhages into muscle are characteristic of what?

Back 31

vitamin C deficiency

Front 32

nearly 90% of cases of hereditary nonpolyposis colorectal cancer are linked to mutations in what?

Back 32

mismatch repair genes - e.g. hMLH1 & hMSH2

Front 33

hypolglycemia with hypoketosis after fasting suggests what? accumulation of organic dicarboxylic acids suggests what?

Back 33

a block in fatty acid oxidation - fatty acyl CoA dehydrogenase deficiency: most commonly medium chain acyl CoA dehydrogenase (MCAD) deficiency

Front 34

dementia, ataxia, ophthalmoplegia?

Back 34

wernicke encephalopathy

Front 35

in what people does wernicke encephalopathy typically develop? what is it a result of?

Back 35

alcoholics; thiamine deficiency

Front 36

what are the four major enzymes requiring thiamine pyrophosphate?

Back 36

pyruvate dehydrogenase, alpha-ketoglutarate deydrogenase, branched-chain ketoacid dehydrogenase, transketolase

Front 37

a child with ketotic hypoglycemia following a period of fasting most likely has a defect in what?

Back 37

gluconeogenesis (or pathway providing substrates for gluconeogenesis)

Front 38

under fasting conditions, what is the primary substrate for gluconeogenesis?

Back 38

alanine (derived from muscle protein)

Front 39

in a child with ketotic hypoglycemia, if alanine rapidly increases blood glucose, what is the likely defect?

Back 39

defect in protein catabolism (rules out defect in gluconeogenesis)

Front 40

what LOD score is required to establish linkage between two loci?

Back 40

3.00 or higher

Front 41

what LOD score is required to rule out linkage between two loci?

Back 41

-2.00 or less

Front 42

what two red cell enzyme deficiencies are characterized clinically by long 'normal' periods interspersed with episodes of hemolytic anemia triggered by infections and oxidant drug injury?

Back 42

pyruvate kinase deficiency and G6PD deficiency

Front 43

primers in PCR must pair up with what?

Back 43

the 3' sequences of the two strands (sequence of left primer is identical to that of top strand and sequence of right primer is identical to bottom strand written 5'to 3')

Front 44

alopecia is related to deficiency of what vitamin?

Back 44

vitamin A

Front 45

what begins the HMP shunt?

Back 45

conversion of glucose-6-phosphate to 6-phosphogluconate

Front 46

what pathway increases the ratio of NADPH/NADP+?

Back 46

HMP shunt

Front 47

proteins destined to be secreted are synthesized where?

Back 47

on ribosomes associated with RER

Front 48

proteins destined for the cytosol and several organelles are synthesized on what?

Back 48

'free' ribosomes

Front 49

what are the characteristics of abetalipoproteinemia?

Back 49

rare AR disorder characterized by very low levels of serum cholesterol and triglyceride

Front 50

what is absent in abetalipoproteinemia?

Back 50

ApoB-containing lipoproteins (chylomicrons, VLDL, LDL)

Front 51

what enzyme is closely related to the role of folate in lowering the risk of CV disease?

Back 51

homocysteine methyltransferase

Front 52

what does cyanide inhibit?

Back 52

cytochrome oxidase - causes loss of all ATP production associated with oxidative phosphorylation

Front 53

on what chromosome is the Wilms tumor suppressor gene located?

Back 53

chromosome 11

Front 54

a higher Km means a lower what?

Back 54

affinity

Front 55

liver and steroidogenic tissues have a scavenger receptor that recognizes HDL and mediates transfer of cholesterol into these tissues - what is it called?

Back 55

SR-B1

Front 56

triad of ophthalmoplegia, ataxia, and global confusion?

Back 56

Wernicke encephalopathy - requires immediate administration of B1/thiamine

Front 57

where is ribosomal RNA manufactured?

Back 57

nucleolus

Front 58

ingestion of alcohol and what else can exacerbate hyperuricemia/gout?

Back 58

nucleic acids - foods rich in DNA (caviar) or RNA (liver pate and sweetbreads (pancreas)) are sources of purines

Front 59

what is MELAS?

Back 59

mitochondrial encephalomyopaty, lactic acidosis, and stroke-like episodes

Front 60

what is seen on muscle biopsy in patients with MELAS?

Back 60

ragged red muscle fibers and disrupted mitochondria

Front 61

what high-energy compound is formed when succinate thiokinase catalyzes the cleavage of the succinl-CoA thoiester bond?

Back 61

GTP

Front 62

what is the energy source used in protein synthesis (formation of activated elongation factor to which tRNA binds & in transfer of elongating chain from P to A site in ribosome)

Back 62

GTP

Front 63

proteins that fail to achieve normal tertiary and quaternary structures are retained where?

Back 63

RER

Front 64

vitamin B12 deficiency causes an increase in what in urine?

Back 64

methylmalonate (due to low activity of methylmalonyl CoA mutase)

Front 65

1 gram of protein or carbs produces how many kcal of energy?

Back 65

about 4

Front 66

one gram of fat produces how many kcal of energy?

Back 66

9

Front 67

deletion of two nucleotides will lead to what type of mutation?

Back 67

frame-shift

Front 68

children with this disease are generally healthy for the first two years but develop progressive hepatosplenomegaly with accumulation of glucocerebroside in macrophages

Back 68

Gaucher's

Front 69

flaring of the distal femur is common in this disease - may be described as having an Erlenmeyer flask appearance

Back 69

Gaucher's

Front 70

what binds to receptors with zinc finger motifs?

Back 70

steroid hormones

Front 71

what amino acid can partially take the place of niacin?

Back 71

tryptophan - about 2% can be converted to quinolinate, which can then be used in place of niacin in NAD synthesis

Front 72

if misfolded proteins accumulate in large quantities, where will they be found?

Back 72

ER

Front 73

weakness accompanied by difficulty in relaxation that is most pronounced in hands and feet; cataracts, testicular atrophy, heart disease, dementia, baldness?

Back 73

myotonic dystrophy

Front 74

the affected gene in myotonic dystrophy is located on what chromosome? how is it inherited?

Back 74

19; autosomal dominant

Front 75

the DNA polymerase used in PCR is highly resistant to what?

Back 75

heat - comes from bacteria that grow in hot springs

Front 76

during intense exercise, in what form will carbons derived from glucose enter the TCA cycle?

Back 76

acetyl-CoA

Front 77

what syndrome is due to a defect in copper transporting P-type ATPase?

Back 77

Ehlers-Danlos

Front 78

this contributes to hyperlipidemia in type I diabetes (and thus the risk for lipid deposition in the retina)

Back 78

overactive hormone-sensitive lipase

Front 79

dideoxycytidine (an antiviral) works by preventing what?

Back 79

formation of a phosphodiester bond during viral DNA synthesis

Front 80

how is Leber hereditary optic neuropathy inherited?

Back 80

mitochondrial

Front 81

about 20% of patients with 13q syndrome develope what?

Back 81

retinoblastoma