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370 Cards in this Set
- Front
- Back
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What are the three posttranscriptional modifications?
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1. 7-methyl guanine cap on the 5' end
2. Addition of the poly(A) tail to the 3' end 3. Removal of introns |
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What AA is the major carrier of nitrogen byproducts from most tissues in the body?
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Glutamine
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What two AAs have a pKa of 4?
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Aspartic acid and glutamic acid
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How many acetyl CoAs per glucose enter into the TCA cycle?
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2 acetyl CoA per glucose, producing 12 ATPs per acetyl CoA, resulting in a total of 24 ATPs produced from glucose (via acetyl CoA) enter the TCA cycle
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What topoisomerase makes ssDNA cuts, requires no ATP, relaxes supercoils, and acts as the swivel in front of the replication fork?
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Topoisomerase I (Relaxase)
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In prokaryotes, what is the name of the RNA sequence that ribosomes bind to so translation can occur?
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Shine-Dalgarno sequence
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Name the pattern of genetic transmission: both M and F are affected; M-to-M transmission may be present; both parents must be carriers; the trait skips generations; two mutant alleles are needed for disease; and affected children may be born of unaffected adults?
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Autosomal recessive
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What factors are needed for translation in prokaryotes?
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Elongation factor-G and GTP
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What three AAs must patients with maple syrup urine disease not eat?
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Isoleucine, leucine, and valine
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How many high-energy bonds are used to activate an AA?
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2 ATPs, via the amino acyl tRNA synthase enzyme
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What water-soluble vitamin deficiency results in pellagra?
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Niacin (B3)
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What glycolytic enzyme has a high Vmax, high Km, and low affinity for glucose?
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Glucokinase
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How many ATPs are generated per acetyl coenzyme A (CoA)?
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12 ATPs per acetyl CoA that enter the tricarboxylic acid (TCA) cycle (Krebs cycle)
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What cytoplasmic pathway produces NADPH and is a source of ribose 5-phosphate?
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HMP shunt
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What is the main inhibitor of pyruvate dehydrogenase?
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Acetyl CoA (pyruvate to acetyl CoA)
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Where on the codon and anticodon does the wobble hypothesis take place?
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3'end of the codon (third position) on mRNA and 5' end of the anticodon (first position) on tRNA.
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What DNA excision and repair enzyme is deficient in patients with xeroderma pigmentosum?
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Excision endonuclease, which removes thiamine dimers from DNA
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What form of bilirubin is carried on albumin?
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Unconjugated (indirect)
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What are the two ketogenic AAs?
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Leucine and lysine
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Which organisms have polycistronic mRNA?
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Prokaryotes. Polycistronic and prokaryotes both start with P.
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As what compound do the carbons for fatty acid synthesis leave the mitochondria?
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Citrate, via the citrate shuttle
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What four substances increase the rate of gluconeogenesis?
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1. Glucagon
2. NADH 3. Acetyl CoA 4. ATP |
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With what three enzymes is thiamin pyrophosphate (TPP) associated?
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1. α-Ketoglutarate dehydrogenase
2. Pyruvate dehydrogenase 3. Transketolase Thiamine pyrophosphate (TPP) functions as a coenzyme vital to tissue respiration. It is required for the oxidative decarboxylation of pyruvate to form acetyl-coenzyme A, providing entry of oxidizable substrate into the Krebs cycle for the generation of energy |
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What test uses very small amounts of DNA that can be amplified and analyzed without the use of Southern blotting or cloning?
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PCR
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What apoprotein is required for the release of chylomicrons from the epithelial cells into the lymphatics?
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apo B-48
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What enzyme catalyzes the covalent bonding of the AA's carboxyl group to the 3' end of tRNA?
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Aminoacyl-tRNA synthetase, which uses 2 ATPs for this reaction.
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What must be supplemented in patients with medium-chain acyl CoA dehydrogenase (MCAD) deficiency?
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Short-chain fatty acids
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What form of AA is found only in collagen?
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Hydroxyproline
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In a diabetic patient, to what does aldose reductase convert glucose?
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Sorbitol (resulting in cataracts)
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What enzyme catalyzes the rate-limiting step in cholesterol metabolism?
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HMG-CoA reductase
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What is the term for the pH at which the structure carries no charge?
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pI (isoelectric point)
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What enzyme catalyzes the rate-limiting step in gluconeogenesis?
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Fructose-1, 6-bisphosphatase
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What is the drug of choice in treating a patient with hyperuricemia due to underexcretion of uric acid?
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Probenecid, a uricosuric agent
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What enzyme deficiency results in darkening of the urine when exposed to air?
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Homogentisate oxidase deficiency is seen in patients with alcaptonuria.
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In eukaryotes, what transcription factor binds to the TATA box before RNA polymerase II can bind?
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Transcription factor IID
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What enzyme produces an RNA primer in the 5'-3' direction and is essential to DNA replication because DNA polymerases are unable to synthesize DNA without an RNA primer?
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Primase
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What enzyme catalyzes the rate-limiting step in fatty acid synthesis?
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Acetyl CoA carboxylase
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Name the eukaryotic DNA polymerase based on the following information:
• Replicates mitochondrial DNA |
DNA polymerase-γ
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Name the eukaryotic DNA polymerase based on the following information:
• Synthesizes the lagging strand during replication |
DNA polymerase-α
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Name the eukaryotic DNA polymerase based on the following information:
• Synthesizes the leading strand during replication |
DNA polymerase-δ
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What is the order of fuel use in a prolonged fast?
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1. Glucose from liver glycogen
2. Glucose from gluconeogenesis 3. Body protein 4. Body fat |
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Which way will the O2 dissociation curve shift with the addition of 2, 3-bisphosphoglycerate (2, 3-BPG) to adult hemoglobin (Hgb)?
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Shifts it to the right
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What enzyme of pyrimidine synthesis is inhibited by the following?
• 5-FU |
Thymidylate synthase
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What enzyme of pyrimidine synthesis is inhibited by the following?
• Methotrexate |
Dihydrofolate reductase
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What enzyme of pyrimidine synthesis is inhibited by the following?
• Hydroxyurea |
Ribonucleotide reductase
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What is found in the R group if the AA is acidic? Basic?
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If a carboxyl group is the R group, it is acidic; if an amino group is the R group, it is said to be basic.
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What gluconeogenic mitochondrial enzyme requires biotin?
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Pyruvate carboxylase
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What factors are needed for translocation in eukaryotes?
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EF-2 and GTP
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DNA replication occurs during what phase of the cell cycle?
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S phase
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What is the end product of purine catabolism?
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Uric acid
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What causes transcription to stop in eukaryotes?
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The poly(A) site on the DNA
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What enzyme of the TCA cycle catalyzes the production of the following:
• FADH2 |
Succinate dehydrogenase
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What enzyme of the TCA cycle catalyzes the production of the following:
• GTP |
Succinyl CoA synthetase
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What enzyme of the TCA cycle catalyzes the production of the following:
• NADH (hint: 3 enzymes) |
Isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and malate dehydrogenase
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What form of alcohol causes blindness?
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Methanol (wood alcohol)
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How many base pairs upstream is the prokaryotic TATA box promoter?
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There are two bacterial promoter regions upstream. The TATA box is - 10 base pairs upstream, and the -35 promoter site is self-explanatory.
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What are the two essential fatty acids?
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Linoleic acid and linolenic acid
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During a prolonged fast, why is the brain unable to use fatty acids?
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Fatty acids cannot cross the blood-brain barrier; therefore, they cannot be used as an energy source.
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What type of jaundice is seen in Rotor's syndrome?
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Conjugated (direct) hyperbilirubinemia
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If a sample of DNA has 30% T, what is the percent of C?
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Solved as 30% T + 30% A = 60%; therefore, C + G = 40%; then C = 20% and G = 20% (example of Chargaff's rule)
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From where is the energy for gluconeogenesis derived?
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β-Oxidation of fatty acids
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Name the type of mutation:
• The deletion or addition of a base |
Frameshift
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Name the type of mutation:
New codon specifies a different AA |
Missense
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Name the type of mutation:
• Unequal crossover in meiosis with loss of protein function |
Large segment deletions
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Name the type of mutation:
• New codon specifies for the same AA |
Silent
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Name the type of mutation:
• New codon specifies for a stop codon |
Nonsense
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What form of bilirubin can cross the blood-brain barrier?
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Unconjugated free bilirubin
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What AA is broken down into N2O, causing an increase in cyclic guanosine monophosphate (cGMP) of smooth muscle, hence vasodilation?
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Arginine
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What three things are needed to produce a double bond in a fatty acid chain in the endoplasmic reticulum?
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NADPH, O2, and cytochrome b5
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What are the vitamin K–dependent coagulation factors?
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Factors II, VII, IX, X, and proteins C and S
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Is the hydroxyl (–OH) end of DNA and RNA at the 3' or the 5' end?
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3' end. Phosphate (PO4) is at the 5' end.
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How many codons code for AAs? How many for termination of translation?
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61 codons code for AAs and 3 codons (UAA, UGA, UAG) code for the termination of translation.
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What is the enzyme for the oxidative reaction in glycolysis?
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Glyceraldehyde dehydrogenase
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What substrate builds up in Tay-Sachs disease?
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GM2 ganglioside
Caused by a deficiency of β-hexosaminidase A |
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What pattern of genetic transmission is characterized by no transmission from M, maternal inheritance, and the potential for the disease to affect both sons and daughters of affected F?
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Mitochondrial inheritance
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What is the rate-limiting enzyme of glycogen synthesis?
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Glycogen synthase
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What sphingolipid is formed by the union of serine and palmitoyl CoA?
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Sphingosine
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What causes an increase in bone mineralization and Ca2+ along with PO4- absorption from the GI tract and kidney tubules?
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Vitamin D
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What two sugars can be used to produce cerebrosides?
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Glucose and galactose
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What group of eukaryotic regulatory proteins has a major factor in controlling the gene expression embryonically?
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Homeodomain proteins
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What causes the lysis of RBCs by oxidizing agents in a G-6-PD deficiency?
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The lack of glutathione peroxidase activity results in a decrease in NADPH production, leaving glutathione in the reduced state.
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All AAs have titration plateaus at what pH values?
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pH of 2 and 9
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What cytoplasmic organelle carries the enzymes for elongation and desaturation of fatty acyl CoA?
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SER
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What is the binding site for RNA polymerase?
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The promoter indicates where transcription will begin.
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What vitamin is necessary for epithelial health?
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Vitamin A is responsible for vision and epithelial health.
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What lipoprotein is formed if an IDL particle acquires cholesterol from a HDL particle?
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LDL
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What structure of a protein describes the interaction among subunits?
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Quaternary structure
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What is the only factor of enzyme kinetics that the enzyme affects?
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Ea (activation energy)
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Is the Lac operon activated or inactivated in the presence of both glucose and lactose?
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Inactivated; glucose results in decreased cAMP levels and therefore blocks protein binding between cAMP and CAP.
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At the end of each round of β-oxidation, what is released?
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Acetyl CoA, FADH2, and NADH
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What is the rate-limiting enzyme on glycolysis?
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Phosphofructokinase-1 and costs 1 ATP
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What enzyme of heme synthesis is deficient in the autosomal dominant disorder acute intermittent porphyria?
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Uroporphyrinogen-I synthase
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What enzyme is blocked by disulfiram?
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Aldehyde dehydrogenase
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Deficiencies in what enzyme result in insoluble glycogen synthesis formation?
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α-1, 6 transferase
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What eukaryotic translation enzyme is associated with the following:
• Initiation |
eIF-2 in the P site
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What eukaryotic translation enzyme is associated with the following:
• Elongation |
eEF-1
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What eukaryotic translation enzyme is associated with the following:
• Termination |
No enzymes are needed. When the stop codon reaches the A site, it results in termination.
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What AA undergoes N-glycosylation?
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Asparagine
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What is the pyrimidine intermediate that joins PRPP (5-Phosphoribosyl-1-Pyrophosphate)?
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Orotic acid
(purine metabolism) |
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What intermediate of cholesterol synthesis anchors proteins in the membranes and forms CoA?
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Farnesyl pyrophosphate (FPP)
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What AA is a phenol?
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Tyrosine
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What hormone is activated in adipose tissue when blood glucose levels decrease?
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Hormone-sensitive lipase
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How many NADPHs are used per addition of acetyl CoA into a fatty acid chain?
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2 NADPHs per acetyl CoA
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What factors are needed for elongation in eukaryotes?
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EF-1 and GTP
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What purine base is contained in inosine monophosphate?
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Hypoxanthine (remember, IMP is a precursor for AMP and GMP)
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What are the two ways that nitrogen can enter into the urea cycle?
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Aspartate and carbomoyl PO4-
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What two requirements must be met for the Lac operon to be activated?
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Lactose must be present and glucose must be absent
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Name the phase of the eukaryotic cell cycle:
• Period of cellular growth (translation and transcription) before DNA synthesis |
G1 phase (gap 1)
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Name the phase of the eukaryotic cell cycle:
• Period of cellular growth (translation and transcription) after DNA synthesis |
G2 phase (gap 2)
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Name the phase of the eukaryotic cell cycle:
• Period of DNA replication (preparing for mitosis) |
S phase
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Name the phase of the eukaryotic cell cycle:
• Cells cease replicating (i.e., nerve cell) |
G0 phase
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True or false? RBCs anaerobically use glucose in both the well-fed and fasting states.
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True. Remember, RBCs do not contain mitochondria, so they cannot metabolize aerobically.
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What enzyme of the TCA cycle catalyzes the substrate level phosphorylation?
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Succinyl CoA synthetase
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What apoprotein on HDL activates lecithin–cholesterol acyltransferase (LCAT)?
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apo A-1
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What three AAs are used to synthesize the purine ring?
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1. Glycine
2. Aspartate 3. Glutamine |
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How many ATPs are produced from cytoplasmic NADH oxidation using the glycerol phosphate shuttle?
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2 ATPs by oxidative phosphorylation
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What enzyme is deficient in patients with PKU?
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Phenylalanine hydroxylase
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What three steps of the TCA cycle generate NADH?
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1. Malate dehydrogenase
2. Isocitrate dehydrogenase 3. α-Ketoglutarate dehydrogenase |
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What two enzymes of heme synthesis are inhibited by lead?
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ALA dehydrogenase and ferrochelatase
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What enzyme, induced by insulin and activated by apo C-II, is required for chylomicron and VLDL metabolism?
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Lipoprotein lipase
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What is the most common genetic deficiency resulting in hemolytic anemia?
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G-6-PD deficiency; pyruvate kinase deficiency is second.
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Are the following conditions associated with a negative or positive nitrogen balance?
• AA deficiency |
Negative
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Are the following conditions associated with a negative or positive nitrogen balance?
• Growth |
Positive
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Are the following conditions associated with a negative or positive nitrogen balance?
• Pregnancy |
Positive
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Are the following conditions associated with a negative or positive nitrogen balance?
• Uncontrolled DM |
Negative
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Are the following conditions associated with a negative or positive nitrogen balance?
• Starvation |
Negative
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Are the following conditions associated with a negative or positive nitrogen balance?
• Infection |
Negative
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Are the following conditions associated with a negative or positive nitrogen balance?
• Recovery from injury |
Positive
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Are the following conditions associated with a negative or positive nitrogen balance?
• Kwashiorkor |
Negative
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Why is the liver unable to metabolize ketone bodies?
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Hepatocytes lack the enzyme succinyl CoA acetoacetyl CoA transferase (thiophorase).
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What toxin ADP-ribosylates via Gs protein to increase cAMP?
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Cholera toxin
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What two vitamins are inactivated when they come in contact with acetaldehyde?
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Thiamine and folate
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Name the end product or products:
• Fatty acid synthesis |
Palmitate
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Name the end product or products:
• Fatty acid oxidation |
Acetyl CoA and propionyl CoA (in odd chain fatty acids)
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What is the term for production of a DNA copy from an RNA molecule?
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Reverse transcription
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What two monosaccharides are produced when lactose is hydrolyzed?
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Galactose and glucose
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What mineral is required for cross-linking of collagen molecules into fibrils?
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The enzyme lysyl oxidase requires Cu2+and O2 to function properly.
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What blotting technique uses the following for analysis?
• DNA |
Southern blot
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What blotting technique uses the following for analysis?
• Protein |
Western blot
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What blotting technique uses the following for analysis?
• RNA |
Northern blot
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How many high-energy bonds does the cycle of elongation cost?
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Four high energy bonds, two from ATP in AA activation and two from GTP
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What enzyme of purine synthesis is inhibited by allopurinol and 6-mercaptopurine?
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PRPP aminotransferase
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True or false? The urea cycle takes place in both the cytoplasm and the mitochondria.
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True. Remember, carbamoyl phosphate synthetase and ornithine transcarbamoylase are mitochondrial enzymes.
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What is the only fatty acid that is gluconeogenic?
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Propionic acid
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What enzyme has a 5' to 3' synthesis of the Okazaki fragments, 3' exonuclease activity, and 5' exonuclease activity?
|
DNA polymerase I
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In what organelle does the TCA cycle occur?
|
Mitochondria
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Do genomic or cDNA libraries contain introns, exons, promoters, enhancers, and are they fragmented?
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Genomic libraries are made from nuclear DNA, are fragmented, and contain all sequences found in the particular genome copied.
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What enzyme is deficient in selective T cell immunodeficiency?
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Purine nucleoside phosphorylase
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True or false? Adipose tissue lacks glycerol kinase.
|
True. Adipose depends on glucose uptake for dihydroxyacetone phosphate (DHAP) production for triglyceride synthesis.
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In what form is excess folate stored in the body?
|
N-5-methyl THF
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What is the term for taking an mRNA molecule and arranging the AA sequence forming a protein?
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Translation
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What enzyme is blocked by hydroxyurea?
|
Ribonucleotide reductase
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What protein carries free fatty acids to the liver?
|
Albumin
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What substrate is built up in Niemann-Pick disease?
|
Sphingomyelin
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True or false? Methylation of bacterial DNA prevents restriction endonuclease from cutting its own chromosomes.
|
True. Restriction endonucleases cut only unmethylated DNA.
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What two AAs have a pKa of 10?
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Lysine and tyrosine
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What is the only enzyme in the body that uses N-5-methyl folate?
|
Homocysteine methyl transferase
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How can you differentiate vitamin K from vitamin C deficiency by bleeding time and PT levels?
|
Vitamin K deficiency has normal bleeding time and increased PT, and vitamin C deficiency has increased bleeding time and normal PT.
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What is the term for a unit of DNA that encodes a particular protein or RNA molecule?
|
A gene (a rather simple definition but accurate)
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Is the coding or the template strand of DNA identical to mRNA (excluding the T/U difference)?
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The coding strand is identical to mRNA, and the template strand is complementary and antiparallel.
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What enzyme is deficient in acute intermittent porphyria?
|
porphobilinogen deaminase
|
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What five cofactors and coenzymes are required by pyruvate dehydrogenase?
|
1. TTP
2. Lipoic acid 3. Coenzyme A from pantothenate 4. NAD(H) (from niacin or tryptophan) 5. FADH2 (from riboflavin) |
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What pattern of genetic transmission affects only M and has no M-to-M transmission, and mother is usually an unaffected carrier?
|
X-linked recessive
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To what does aldose reductase convert galactose?
|
Galactitol
|
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Name three purine bases that are not found in nucleic acids.
|
Xanthine, hypoxanthine, theophylline, theobromine, caffeine, and uric acid are all purines.
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What water-soluble-vitamin deficiency is associated with cheilosis and magenta tongue?
|
Riboflavin (B2)
|
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What is the precursor of all sphingolipids?
|
Ceramide
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What three substances stimulate glycogenolysis?
|
1. Ca2+ : calmodulin ratio
2. Epinephrine 3. Glucagon |
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What is the primer for the synthesis of the second strand in production of cDNA from mRNA?
|
The hairpin loop made by reverse transcriptase at the 3' end of the first strand is the primer.
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What factors are needed for elongation in prokaryotes?
|
EF-Tu or EF-ts and GTP
|
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What restriction endonuclease site is destroyed in sickle β-globin allele?
|
MstII; changing codon 6 (from A to T) destroys the restriction site.
|
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What complex is needed for propionyl CoA carboxylase?
|
Biotin, ATP, and CO2
|
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What enzyme catalyzes the reversible oxidative deamination of glutamate and produces the TCA cycle intermediate α-ketoglutarate?
|
Glutamate dehydrogenase
|
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What enzyme is deficient in congenital erythropoietic porphyria?
|
Uroporphyrinogen III cosynthase
|
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What is the drug of choice for treating a patient with hyperuricemia due to overproduction of uric acid?
|
Allopurinol
|
|
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What is the maximum rate possible with a given amount of enzyme?
|
Vmax
|
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From what do catalase, superoxide dismutase, and glutathione peroxidase defend the cell?
|
Production of oxygen free radicals
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What signals are used to direct an enzyme to a lysosome?
|
Phosphorylation of mannose residues
|
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What enzyme catalyzes the rate-limiting step of the urea cycle?
|
Carbamoyl phosphate synthetase I
|
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What liver enzyme, for triglyceride synthesis, converts glycerol to glycerol-3-phosphate?
|
Glycerol kinase
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What organ functions to keep blood glucose levels normal through both well-fed and fasting states and produces ketones in response to increased fatty acid oxidation?
|
Liver
|
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What pattern of inheritance does G-6-PD deficiency follow?
|
X-linked recessive
|
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What is the term for conversion of a dsDNA molecule to the base sequence of an ssRNA molecule?
|
Transcription (C comes before L in the alphabet, and transCription comes before transLation)
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Via what cell surface receptor does HDL cholesterol from the periphery enter hepatoceles?
|
Scavenger receptor (SR-B1)
|
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Which shuttle is used to bring fatty acyl CoA from the cytoplasm for ketogenesis?
|
Carnitine acyl CoA transferase II
|
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What enzyme is blocked by 5-FU?
|
Thymidylate synthetase
|
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What disease has a genetically low level of UDPglucuronate transferase, resulting in elevated free unconjugated bilirubin?
|
Gilbert's syndrome
|
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What AA has a pKa of 13?
|
Arginine
|
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What X-linked recessive disorder is characterized by hyperuricemia, spastic cerebral palsy, mental retardation, and self-mutilation?
|
Lesch-Nyhan syndrome
|
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How many ATPs per glucose are generated from glycolysis in RBCs?
|
2 ATPs, because RBCs use only anaerobic metabolism.
|
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What enzyme catalyzes the rate-limiting step in glycogenolysis?
|
Glycogen phosphorylase
|
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Would a G-C or an A-T rich dsDNA sequence have a higher melting point? Why?
|
G-C rich sequences, because they have 3 hydrogen bonds, where A-T has 2 hydrogen bonds, resulting in higher melting points.
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As what AAs do muscles send nitrogen to the liver?
|
Alanine and glutamine
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What sphingolipid cannot be produced without sialic acid and amino sugars?
|
Ganglioside
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|
|
What happens to affinity if you increase Km?
|
Affinity decreases; they are inversely proportional.
|
|
|
What type of bilirubin is found in neonatal jaundice?
|
Indirect or unconjugated
|
|
|
What two AAs do not have more than one codon?
|
Methionine (start) and tryptophan are the only two AAs with only one codon.
|
|
|
What bonds are broken by exonucleases?
|
External 3', 5' PDE bonds
|
|
|
How can a genetic deficiency of carbamoyl phosphate synthetase be differentiated from an ornithine transcarbamoylase deficiency?
|
Uracil and orotic acid levels increase with ornithine transcarbamoylase deficiency and are normal in carbamoyl phosphate synthetase deficiency.
|
|
|
Name the lipoprotein based on the following characteristics.
• apo E |
IDL
|
|
|
Name the lipoprotein based on the following characteristics.
• apo B-100 |
LDL
|
|
|
Name the lipoprotein based on the following characteristics.
• apo E, apo B-100, apo C-II |
VLDL
|
|
|
Name the lipoprotein based on the following characteristics.
• apo A-1, apo E, apo C-II |
HDL
|
|
|
Name the lipoprotein based on the following characteristics.
• apo E, apo C-II, apoB-48 |
Chylomicrons
|
|
|
True or false? There is no hormonal control to the TCA cycle.
|
True. The energy status of the cell dictates if the cycle is running or relaxing.
|
|
|
What are the three tissues where triacylglycerols are produced?
|
1. Liver
2. Muscle 3. Adipose tissue |
|
|
What toxin ADP-ribosylates via Gi to increase cAMP?
|
Pertussis toxin
|
|
|
What enzyme catalyzes the rate-limiting step in heme synthesis?
|
δ-ALA synthase
|
|
|
What cycle is responsible for converting to glucose in the liver the lactate produced in the RBCs?
|
Cori cycle
|
|
|
What enzyme is used to remove the hairpin loop during production of cDNA from mRNA?
|
S1 nuclease
|
|
|
Does a saturated fatty acid have double bonds?
|
No, unsaturated fatty acids have double bonds.
|
|
|
What pyrimidine base is found
• Only in RNA? |
Uracil
|
|
|
What pyrimidine base is found
• Only in DNA? |
Thymine
|
|
|
What pyrimidine base is found
• In both DNA and RNA? |
Cytosine
|
|
|
What two AAs require vitamin C for hydroxylation?
|
Proline and lysine
|
|
|
What is the only organ in the body that can produce ketone bodies?
|
The liver (in the mitochondria)
|
|
|
What determines the rate of reaction?
|
The energy of activation
|
|
|
What is the term for the number of trinucleotide repeats increasing with successive generations and correlating with increased severity of disease?
|
Anticipation, associated with fragile X syndrome; Huntington's disease is also associated with a decrease in onset of age.
|
|
|
What enzyme is blocked by methotrexate/ trimethoprim?
|
Dihydrofolate reductase
|
|
|
What fructose metabolism enzyme is deficient in patients with vomiting, apathy, diarrhea, jaundice, proximal renal tubular acidosis, hypoglycemia, and hyperuricemia?
|
Aldolase B deficiencies are treated by eliminating fructose from the diet.
|
|
|
What enzyme catalyzes the rate-limiting step in purine synthesis?
|
PRPP aminotransferase
|
|
|
What water-soluble-vitamin deficiency is associated with poor wound healing, easy bruising, bleeding gums, anemia, and painful glossitis?
|
Vitamin C
|
|
|
What three substrates control the enzyme PEPCK for the conversion of oxaloacetate (OAA) to pyruvate in the cytoplasm?
|
1. Cortisol (stimulates PEPCK)
2. Glucagon 3. GTP |
|
|
What genetic defect is characterized by coarse facial features, gingival hyperplasia, macroglossia, psychomotor and growth retardation, club foot, claw hand, cardiorespiratory failure, and death in the first decade of life?
|
I-cell disease is a result of a genetic defect affecting the phosphorylation of mannose residues.
|
|
|
What two glycolytic enzymes catalyze the substrate-level phosphorylations?
|
3-Phosphoglycerate kinase and pyruvate kinase; this produces two ATPs per enzyme (total four ATPs)
|
|
|
What pathway uses HMG CoA synthetase in the cytoplasm?
|
Cholesterol biosynthesis
|
|
|
Where in the body is heme converted to bilirubin?
|
RES(Reticular endothelial system)
|
|
|
What protein is required by prokaryotic RNA polymerases to initiate transcription at the promoter region of DNA?
|
Sigma factor
|
|
|
What enzyme catalyzes the rate-limiting step in pyrimidine synthesis?
|
Aspartate transcarbamylase
|
|
|
What are the two actions of calcitonin?
|
It increases Ca2+ excretion from the kidney and increases bone mineralization.
|
|
|
What enzyme of the purine salvage pathway is deficient in the following?
• Selective T-cell immunodeficiency |
Purine nucleoside phosphorylase
|
|
|
What enzyme of the purine salvage pathway is deficient in the following?
• SCID |
Adenosine deaminase
|
|
|
What enzyme of the purine salvage pathway is deficient in the following?
• Lesch-Nyhan syndrome |
HGPRT
|
|
|
In what cycle does glucose go to the muscle, where it is converted to pyruvate and then into alanine before being taken back to the liver?
|
Alanine cycle
|
|
|
What is the primary end product of pyrimidine synthesis?
|
UMP
|
|
|
What pyrimidine base is produced by deaminating cytosine?
|
Uracil
|
|
|
What AA is classified as basic even though its pK is 6.5 to 7?
|
Histidine, because of the imidazole ring found in the R group, is basic.
|
|
|
What enzyme is deficient in hereditary protoporphyria?
|
Ferrochelatase
|
|
|
What elongation factor is inactivated by ADP ribosylation, preventing translation?
|
eEF-2 is the site where Pseudomonas and Diphtheria toxins work.
|
|
|
Is linolenic acid an omega-3 or omega-6 fatty acid?
|
Omega-3; linoleic is omega-6
|
|
|
How many ATPs per glucose are generated in glycolysis?
|
38 ATPs if aerobic, 2 ATPs if anaerobic (36 ATPs[malate shuttle] + 4 ATPs[Glycolysis] - 2 ATPs[phosphorylate glucose] = 38 ATPs)
|
|
|
Name the three ketone bodies.
|
Acetoacetate, acetone, and β-hydroxybutyrate
|
|
|
What three bases are pyrimidines?
|
1. Cytosine
2. Uracil (only in RNA) 3. Thymidine |
|
|
Name the RNA subtype based on the following:
• The most abundant form of RNA in the cell |
rRNA
|
|
|
Name the RNA subtype based on the following:
• Found only in the nucleus of eukaryotes and functions to remove introns from mRNA |
snRNA
|
|
|
Name the RNA subtype based on the following:
• Only type of RNA that is translated |
mRNA
|
|
|
Name the RNA subtype based on the following:
• Carries AA to the ribosome for protein synthesis |
tRNA
|
|
|
Name the RNA subtype based on the following:
• RNA molecules with enzymatic activity |
Ribozymes
|
|
|
Name the RNA subtype based on the following:
• Found only in the nucleus of eukaryotic cells and are precursors of mRNA |
hnRNA
|
|
|
What enzyme is deficient in the following glycogen storage disease?
• von Gierke's disease |
Glucose-6-phosphatase
|
|
|
What enzyme is deficient in the following glycogen storage disease?
• Pompe's disease |
Lysosomal α-1, 4-glucosidase
|
|
|
What enzyme is deficient in the following glycogen storage disease?
• McArdle's disease |
Muscle glycogen phosphorylase
|
|
|
What enzyme is deficient in the following glycogen storage disease?
• Hers' disease |
Hepatic glycogen phosphorylase
|
|
|
In prokaryotes, what is the term for a set of structural genes that code for a select group of proteins and the regulatory elements required for the expression of such gene?
|
Operon
|
|
|
What are the two most common AAs found in histones?
|
Lysine and arginine
|
|
|
What five pathways use SAM (S-adenosylmethionine) as the methyl donor?
|
1. Epinephrine synthesis
2. Phosphatidyl choline 3. Creatine 4. Methylation of cytosine 5. N-methyl cap of mRNA |
|
|
What complex of the ETC contains Cu2+?
|
Complex 4
|
|
|
How many ATPs per glucose are produced by pyruvate dehydrogenase?
|
6 ATPs (remember 2 pyruvates per glucose are produced, and 2 NADHs result from production of acetyl CoA, so 6 ATPs)
|
|
|
What is the size of the prokaryotic ribosome?
|
70S ribosomes in prokaryotes and 80S ribosomes in eukaryotes
|
|
|
What type of fatty acid is associated with a decrease in serum triglycerides and cardiovascular disease?
|
Omega-3 fatty acids
|
|
|
What disease is produced by a deficiency in the enzyme tyrosinase?
|
Albinism. Tyrosine is converted to melanin by the enzyme tyrosinase.
|
|
|
In what form are triglycerides sent to adipose tissue from the liver?
|
VLDLs
|
|
|
What determines the rate of a reaction?
|
The energy of activation (Ea)
|
|
|
What is the rate-limiting enzyme of the HMP shunt?
|
G-6-PD
|
|
|
What vitamin is necessary for the transfer of one amino group from a carbon skeleton to another?
|
Pyridoxal phosphate is derived from vitamin B6 and is needed to transfer the amino groups of one carbon skeleton to another.
|
|
|
What is the only sphingolipid that contains choline and PO4?
|
Sphingomyelin (lecithin also, but it is not a sphingolipid)
|
|
|
What protein catalyzes the formation of the last PDE bond between the Okazaki fragments to produce a continuous strand?
|
DNA ligase
|
|
|
What type of damage to the kidneys is caused by drinking ethylene glycol (antifreeze)?
|
Nephrotoxic oxylate stones
|
|
|
What water-soluble-vitamin deficiency may result from eating raw eggs?
|
Biotin (only if eaten in large quantities)
|
|
|
Regarding the Lac operon, for what do the following genes code?
• Z gene |
β-Galactosidase
|
|
|
Regarding the Lac operon, for what do the following genes code?
• Y gene |
Galactoside permease
|
|
|
Regarding the Lac operon, for what do the following genes code?
• I gene |
Lac repressor protein
|
|
|
Regarding the Lac operon, for what do the following genes code?
• A gene |
Thiogalactoside transacetylase
|
|
|
What attaches to protons and allows them to enter into the mitochondria without going through the ATP-generating system?
|
2, 4-Dinitrophenol
|
|
|
1-α-Hydroxylase activity is increased in response to what two physiologic states? (hint: think of vitamin D activity)
|
Hypocalcemia and hypophosphatemia
|
|
|
What is the major ketone body produced during alcoholic ketoacidosis?
|
β-Hydroxybutyrate
|
|
|
What enzyme catalyzes the rate-limiting step in the TCA cycle?
|
Isocitrate dehydrogenase
|
|
|
Name the pattern of genetic transmission characterized thus: both M and F are affected; M may transmit to M; each generation has at least one affected parent; and one mutant allele may produce the disease.
|
Autosomal dominant
|
|
|
What bonds are broken by endonucleases?
|
Internal 3', 5' PDE bonds
|
|
|
Name the GLUT transporter based on the following:
• Found in liver and pancreatic β-cells |
GLUT 2
|
|
|
Name the GLUT transporter based on the following:
• Found in skeletal muscle and adipose tissues |
GLUT 4
|
|
|
Name the GLUT transporter based on the following:
• Found in most tissues, including brain and RBCs |
GLUT 3 and 4
|
|
|
What enzyme catalyzes the rate-limiting step in fatty acid oxidation?
|
Carnitine acyltransferase-I
|
|
|
What enzyme of the TCA cycle also acts as complex II of the ETC?
|
Succinate dehydrogenase
|
|
|
What is the term for chemicals that keep the pH constant despite the formation of acids and bases during metabolism?
|
Buffers (remember that buffers are best when they are used in a pH range near its pK)
|
|
|
In the mitochondria, what complex is needed for pyruvate carboxylase to catalyze the reaction from pyruvate to OAA?
|
Biotin, ATP, and CO2
|
|
|
How many ATPs are produced from cytoplasmic NADH oxidation using the malate shuttle?
|
3 ATPs by oxidative phosphorylation
|
|
|
What is the rate-limiting step of the following?
• Fatty acid synthesis |
Acetyl CoA carboxylase
|
|
|
What is the rate-limiting step of the following?
• β-Oxidation |
Carnitine acyltransferase I
|
|
|
What is the rate-limiting step of the following?
• Ketogenolysis |
HMG CoA synthase
|
|
|
What is the rate-limiting step of the following?
• Cholesterol synthesis |
HMG CoA reductase
|
|
|
What direction does RNA polymerase move along the template strand of DNA during transcription?
|
3'-5' direction, synthesizing RNA in the 5'-3' direction
|
|
|
True or false? Histidine activates the histidine operon.
|
False. Histidine operon is activated when there are low intracellular levels of histidine.
|
|
|
What organ is responsible for the elimination of excess nitrogen from the body?
|
The kidneys excrete the excess nitrogen from the body as urea in the urine.
|
|
|
What is the only way to increase maximum velocity (Vmax)?
|
Increase enzyme concentrations
|
|
|
Name the two purine bases found in both DNA and RNA.
|
Adenine and guanine
|
|
|
What prokaryotic positioning enzyme in translation is blocked by the following?
• Tetracycline |
EF-Tu and EF-Ts of the 30S ribosomal subunit
|
|
|
What prokaryotic positioning enzyme in translation is blocked by the following?
• Erythromycin |
EF-G of the 50S subunit
|
|
|
What prokaryotic positioning enzyme in translation is blocked by the following?
• Streptomycin |
IF-2 of the 30S subunit
|
|
|
True or false? DNA polymerases can correct mistakes, whereas RNA polymerases lack this ability.
|
True. DNA polymerases have 3'-5' exonuclease activity for proofreading.
|
|
|
What are the two precursors of heme?
|
Glycine and succinyl-CoA
|
|
|
What two factors cause PTH to be secreted?
|
A decrease in Ca2+ and an increase in PO4-
|
|
|
What are the nonoxidative enzymes of the HMP shunt? Are the reactions they catalyze reversible or irreversible?
|
Transketolase and transaldolase. The reactions they catalyze are reversible.
|
|
|
What are the five AAs that are both ketogenic and glucogenic?
|
Isoleucine, threonine, tryptophan, tyrosine, and phenylalanine
|
|
|
What artificial sweetener must patients with PKU avoid?
|
Aspartame
|
|
|
Cri-du-chat syndrome results in a terminal deletion of the short arm of what chromosome?
|
Chromosome 5
|
|
|
What substrate gets built up in Gaucher's disease?
|
Glucosyl cerebroside
|
|
|
What protein prevents ssDNA from reannealing during DNA replication?
|
Single-strand DNA binding protein
|
|
|
What type of jaundice is seen in Dubin-Johnson syndrome?
|
Conjugated (direct) hyperbilirubinemia, a transport defect
|
|
|
What type of DNA library is made from the mRNA from a tissue expressing a particular gene?
|
cDNA libraries are derived from mRNA, are continuous, and contain no introns or regulatory elements.
|
|
|
What is the most common cause of vitamin B6 deficiency?
|
Isoniazid treatment
|
|
|
What lysosomal enzyme is deficient in
• Gaucher's disease? |
Glucocerebrosidase
|
|
|
What lysosomal enzyme is deficient in
• Niemann-Pick disease? |
Sphingomyelinase
|
|
|
What lysosomal enzyme is deficient in
• Tay-Sachs disease? |
Hexosaminidase A
|
|
|
What are the three exceptions to the rule of codominant gene expression?
|
Barr bodies in females, T-cell receptor loci, and immunoglobulin light and heavy chain loci
|
|
|
How many kilocalories per gram are produced from the degradation of fat? CHO? Protein?
|
9 kcal/g from fat metabolism; 4 kcal/g from both CHO and protein metabolism
|
|
|
What is the only way to increase the Vmax of a reaction?
|
Increase the concentration of enzymes
|
|
|
From which two substances are phospholipids made?
|
Diacylglycerols and phosphatidic acid
|
|
|
What intermediate enables propionyl CoA to enter into the TCA cycle?
|
Succinyl CoA
|
|
|
What vitamin is an important component of rhodopsin?
|
Vitamin A
|
|
|
What is the term to describe the 5'-3' sequence of one strand being the same as the opposite 5'-3' strand?
|
Palindrome
|
|
|
What gluconeogenic enzyme is absent in muscle, accounting for its inability to use glycogen as a source for blood glucose?
|
Glucose-6-phosphatase
|
|
|
What is the term for vitamin D deficiency prior to epiphyseal fusion?
|
Rickets prior to fusion, osteomalacia if the deficiency occurs after epiphyseal fusion.
|
|
|
In what disease is there a genetic absence of UDP-glucuronate transferase, resulting in an increase in free unconjugated bilirubin?
|
Crigler-Najjar syndrome
|
|
|
What enzyme requires molybdenum as a cofactor?
|
Xanthine oxidase
|
|
|
At what three sites can the HMP shunt enter into glycolysis?
|
1. Fructose-6-phosphate
2. Glucose-6-phosphate 3. Glyceraldehyde-3-phosphate |
|
|
What is the term for the pH range where the dissociation of H+ occurs?
|
pK (think of it as where half is base and half is acid)
|
|
|
What regulates the rate of ketone body formation?
|
The rate of β-oxidation
|
|
|
What are the eight liver-specific enzymes?
|
1. Fructokinase
2. Glucokinase 3. Glycerol kinase 4. PEPCK 5. Pyruvate carboxylase 6. Galactokinase 7. Fructose-1, 6-bisphosphatase 8. Glucose-6-phosphatase |
|
|
How many bases upstream is the eukaryotic TATA box promoter?
|
There are two eukaryotic upstream promoters. The TATA box is –25 base pairs upstream; the CAAT box is –75 bases upstream.
|
|
|
What is needed to initiate translation?
|
IF and GTP (eIF for eukaryotes)
|
|
|
What part of the 30S ribosome binds to the Shine-Dalgarno sequence?
|
16S subunit
|
|
|
What component of the ETC is inhibited by the following?
• Barbiturates |
Complex I
|
|
|
What component of the ETC is inhibited by the following?
• Antimycin A |
Cytochrome b/c1
|
|
|
What component of the ETC is inhibited by the following?
• Cyanide |
Cytochrome a/a3
|
|
|
What component of the ETC is inhibited by the following?
• Oligomycin |
Fo/F1 complex
|
|
|
What component of the ETC is inhibited by the following?
• Atractyloside |
ATP/ADP Translocase
|
|
|
What component of the ETC is inhibited by the following?
• CO |
Cytochrome a/a3
|
|
|
What component of the ETC is inhibited by the following?
• Rotenone |
Complex I
|
|
|
What component of the ETC is inhibited by the following?
• Azide |
Cytochrome a/a3
|
|
|
What AA is a precursor of the following substances?
• Serotonin |
Tryptophan
|
|
|
What AA is a precursor of the following substances?
• GABA |
Glutamate
|
|
|
What AA is a precursor of the following substances?
• Histamine |
Histidine
|
|
|
What AA is a precursor of the following substances?
• Creatine |
Glycine/arginine
|
|
|
What AA is a precursor of the following substances?
• NAD |
Tryptophan
|
|
|
What AA is a precursor of the following substances?
• N2O |
Arginine
|
|
|
What two enzymes are vitamin B12-dependent
|
Homocysteine methyl transferase and methylmalonyl CoA transferase
|
|
|
What two post-transcriptional enzymes in collagen synthesis require ascorbic acid to function properly?
|
Prolyl and lysyl hydroxylases
|
|
|
What three organs participate in production of vitamin D?
|
1. Skin
2. Liver 3. Kidney |
|
|
What water-soluble-vitamin deficiency is associated with neural tube defects in the fetus?
|
Folic acid
|
|
|
What phase of Interphase is haploid (N)?
|
G1 phase; G2 and S phase are diploid (2N).
|
|
|
What neurotransmitter inhibits the optic nerve bipolar cell and shuts off in response to light?
|
Glutamate
|
|
|
Which of the following—DNA methylating enzymes, scaffolding proteins, histone acetylases, or deacetylases—is a regulator of eukaryotic gene expression?
|
Histone acetylases is a regulator favoring gene expression. All of the others favor inactivation.
|
|
|
Name the pattern of genetic transmission characterized thus: both M and F affected; no M-to-M transmission; affected M passes trait to all daughters, every generation; affected F passes trait to both sons and daughters; a single mutant allele can produce the disease.
|
X-linked dominant
|
|
|
What fat-soluble vitamin is connected to selenium metabolism?
|
Vitamin E
|
|
|
Why are eukaryotes unable to perform transcription and translation at the same time like prokaryotes?
|
In eukaryotes transcription occurs in the nucleus and translation in the cytoplasm.
|
|
|
What is determined by the secondary structure of an AA?
|
The folding of an AA chain
|
|
|
What three vitamin deficiencies are associated with homocystinemia?
|
Folate, vitamin B12, and vitamin B6
|
|
|
If the pH is more acidic than the pI, does the protein carry a net positive or net negative charge?
|
When the pH is more acidic than the pI, it has a net positive charge, and when the pH is more basic than the pI, it has a net negative charge.
|
|
|
What form of continuous DNA, used in cloning, has no introns or regulatory elements?
|
cDNA, when it is made from mRNA
|
|
|
What is the start codon, and what does it code for in eukaryotes? Prokaryotes?
|
The one start codon, AUG, in eukaryotes codes for methionine and in prokaryotes formylmethionine.
|
|
|
What parasite found in raw fish can produce vitamin B12 deficiency?
|
Diphyllobothrium latum
|
|
|
Methylating uracil produces what pyrimidine base?
|
Thymine
|
|
|
Name the eukaryotic RNA polymerase based on the following:
• Synthesizes tRNA, snRNA, and the 5S rRNA |
RNA polymerase III
|
|
|
Name the eukaryotic RNA polymerase based on the following:
• Synthesizes hnRNA, mRNA, and snRNA |
RNA polymerase II
|
|
|
Name the eukaryotic RNA polymerase based on the following:
• Synthesizes 28S, 18S and 5.8S rRNAs |
RNA polymerase I
|
|
|
What is the primary screening test used to detect HIV-infected individuals? Confirmatory test?
|
ELISA is used as a screening test because it is very sensitive; Western blot is used as a confirmatory test because it detects antibodies (protein) to the HIV virus.
|
|
|
How many covalent bonds per purine-pyrimidine base pairing are broken during denaturation of dsDNA?
|
None. Denaturation of dsDNA breaks hydrogen bonds, not covalent bonds.
|
|
|
How many hydrogen bonds link A-T? C-G?
|
A-T are linked by 2 hydrogen bonds, C-G by 3 hydrogen bonds.
|
|
|
What DNA replication enzyme breaks the hydrogen bond of base pairing, forming two replication forks?
|
Helicase (requires ATP for energy)
|
