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81 Cards in this Set

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  • Back
what catalyzes the irreversible conversion of pyruvate to acetyl CoA?
pyruvate dehydrogenase
if pyruvate dehydrogenase is absent, what will it be converted to?
alanine via alanine aminotransferase;
lactate via lactate dehydrogenase
what is the porphyrin ring of heme derived from?
TCA cycle intermediate succinyl-CoA and AA glycine; this initial synthetic step, which is rate-limiting, is catalyzed by aminolevulinic acid synthase
vitamin K is an important coenzyme for what?
gamma-gluyamylcarboxylase, an enzyme that catalyzes a post-translational modification of a group of calcium-binding proteins
how does vitamin K deficiency manifest in infants?
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
absence of vitamin B12 results in the accumulation of what?
methylmalonyl-CoA (B12 is a cofactor in the conversion of methylmalonyl-CoA to succinyl-CoA)
what is the clinical picture associated with galactokinase deficiency?
very mild disease - only significant complication is cataract formation
what does homozygous deficiency of galactose-1-phosphate uridyltransferase lead to?
severe disease, culminating in death in infancy: impaired renal tubular absorption leading to aminoaciduria, GI symptoms, hepatosplenomegaly, cataracts, bleeding diatheses, hypoglycemia, and MR
what is the process of glycolysis?
converts glucose into pyruvate with concomitant production of ATP
name three ketone bodies
acetoacetate, beta-hydroxybutyrate, and acetone
when/how are ketone bodies produced?
produced by liver in the fasting state by beta-oxidation of fatty acids
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
what is the mechanism of cipro?
inhibits DNA gyrase (prokaryotic topoisomerase II) essential for DNA replication
what is the mechanism of statins?
HMG-CoA reductase inhibitors
this syndrome is characterized by MR, nervous system malformations, rocker-bottom feet, polydactyly, and cleft lip and palate
Trisomy 13/Patau syndrome
where does the clinically important degradation of ethanol to acetaldehyde occur in humans?
peroxisomes and SER (P450)
where is acetaldehyde oxidized to acetate?
what is the defect in von Gierke's?
what is Smith-Lemli-Opitz syndrome?
recessive genetic disease - first single-gene disease to be associated with multiple malformations
microcephaly, MR, hypotonia, incomplete development of genitalia, high forehead, pyloric stenosis, syndactyly of 2nd and 3rd toes are characteristic of what syndrome?
what technique is used to identify a specific protein that may be present in very small concentrations in a complex protein mixture?
Western blotting
what technique utilizes DNA-RNA hybridization to determine the size and abundance of RNA for a specific gene?
Northern blotting
what technique utilizes DNA-DNA hybridization?
Southern blotting
what technique involves DNA-protein interactions?
Southwestern blotting - a protein sample is subjected to electrophoresis, transferred to a filter, and exposed to labeled DNA
following treatment of ALL, patients often have a high level of what? how do you treat them?
urate (secondary to breakdown of nucleic acids) - Rx: allopurinol to decrease plasma urate levels (inhibition of xanthine oxidase)
what is the best technique for determining whether a gene is expresed in a particular cell type?
Northern blot
what is the most common technique used to screen for cystic fibrosis?
what is the primary source of ketones in diabetic ketoacidosis?
free fatty acid breakdown
severe neonatal jaundice, elevated indirect bilirubin, and exchange blood transfusion suggest what?
increased levels of 2,3 BPG, 3-PG, 2-PG, and PEP correspond with what type of hemolytic anemia?
one induced by pyruvate kinase deficiency
perifollicular hemorrhages, fragmentation of hairs, purpura, ecchymoses, splinter hemorrhages, and hemorrhages into muscle are characteristic of what?
vitamin C deficiency
nearly 90% of cases of hereditary nonpolyposis colorectal cancer are linked to mutations in what?
mismatch repair genes - e.g. hMLH1 & hMSH2
hypolglycemia with hypoketosis after fasting suggests what? accumulation of organic dicarboxylic acids suggests what?
a block in fatty acid oxidation - fatty acyl CoA dehydrogenase deficiency: most commonly medium chain acyl CoA dehydrogenase (MCAD) deficiency
dementia, ataxia, ophthalmoplegia?
wernicke encephalopathy
in what people does wernicke encephalopathy typically develop? what is it a result of?
alcoholics; thiamine deficiency
what are the four major enzymes requiring thiamine pyrophosphate?
pyruvate dehydrogenase, alpha-ketoglutarate deydrogenase, branched-chain ketoacid dehydrogenase, transketolase
a child with ketotic hypoglycemia following a period of fasting most likely has a defect in what?
gluconeogenesis (or pathway providing substrates for gluconeogenesis)
under fasting conditions, what is the primary substrate for gluconeogenesis?
alanine (derived from muscle protein)
in a child with ketotic hypoglycemia, if alanine rapidly increases blood glucose, what is the likely defect?
defect in protein catabolism (rules out defect in gluconeogenesis)
what LOD score is required to establish linkage between two loci?
3.00 or higher
what LOD score is required to rule out linkage between two loci?
-2.00 or less
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?
pyruvate kinase deficiency and G6PD deficiency
primers in PCR must pair up with what?
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')
alopecia is related to deficiency of what vitamin?
vitamin A
what begins the HMP shunt?
conversion of glucose-6-phosphate to 6-phosphogluconate
what pathway increases the ratio of NADPH/NADP+?
HMP shunt
proteins destined to be secreted are synthesized where?
on ribosomes associated with RER
proteins destined for the cytosol and several organelles are synthesized on what?
'free' ribosomes
what are the characteristics of abetalipoproteinemia?
rare AR disorder characterized by very low levels of serum cholesterol and triglyceride
what is absent in abetalipoproteinemia?
ApoB-containing lipoproteins (chylomicrons, VLDL, LDL)
what enzyme is closely related to the role of folate in lowering the risk of CV disease?
homocysteine methyltransferase
what does cyanide inhibit?
cytochrome oxidase - causes loss of all ATP production associated with oxidative phosphorylation
on what chromosome is the Wilms tumor suppressor gene located?
chromosome 11
a higher Km means a lower what?
liver and steroidogenic tissues have a scavenger receptor that recognizes HDL and mediates transfer of cholesterol into these tissues - what is it called?
triad of ophthalmoplegia, ataxia, and global confusion?
Wernicke encephalopathy - requires immediate administration of B1/thiamine
where is ribosomal RNA manufactured?
ingestion of alcohol and what else can exacerbate hyperuricemia/gout?
nucleic acids - foods rich in DNA (caviar) or RNA (liver pate and sweetbreads (pancreas)) are sources of purines
what is MELAS?
mitochondrial encephalomyopaty, lactic acidosis, and stroke-like episodes
what is seen on muscle biopsy in patients with MELAS?
ragged red muscle fibers and disrupted mitochondria
what high-energy compound is formed when succinate thiokinase catalyzes the cleavage of the succinl-CoA thoiester bond?
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)
proteins that fail to achieve normal tertiary and quaternary structures are retained where?
vitamin B12 deficiency causes an increase in what in urine?
methylmalonate (due to low activity of methylmalonyl CoA mutase)
1 gram of protein or carbs produces how many kcal of energy?
about 4
one gram of fat produces how many kcal of energy?
deletion of two nucleotides will lead to what type of mutation?
children with this disease are generally healthy for the first two years but develop progressive hepatosplenomegaly with accumulation of glucocerebroside in macrophages
flaring of the distal femur is common in this disease - may be described as having an Erlenmeyer flask appearance
what binds to receptors with zinc finger motifs?
steroid hormones
what amino acid can partially take the place of niacin?
tryptophan - about 2% can be converted to quinolinate, which can then be used in place of niacin in NAD synthesis
if misfolded proteins accumulate in large quantities, where will they be found?
weakness accompanied by difficulty in relaxation that is most pronounced in hands and feet; cataracts, testicular atrophy, heart disease, dementia, baldness?
myotonic dystrophy
the affected gene in myotonic dystrophy is located on what chromosome? how is it inherited?
19; autosomal dominant
the DNA polymerase used in PCR is highly resistant to what?
heat - comes from bacteria that grow in hot springs
during intense exercise, in what form will carbons derived from glucose enter the TCA cycle?
what syndrome is due to a defect in copper transporting P-type ATPase?
this contributes to hyperlipidemia in type I diabetes (and thus the risk for lipid deposition in the retina)
overactive hormone-sensitive lipase
dideoxycytidine (an antiviral) works by preventing what?
formation of a phosphodiester bond during viral DNA synthesis
how is Leber hereditary optic neuropathy inherited?
about 20% of patients with 13q syndrome develope what?