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370 Cards in this Set

  • Front
  • Back
What are the three posttranscriptional modifications?
1. 7-methyl guanine cap on the 5' end
2. Addition of the poly(A) tail to the 3' end
3. Removal of introns
What AA is the major carrier of nitrogen byproducts from most tissues in the body?
Glutamine
What two AAs have a pKa of 4?
Aspartic acid and glutamic acid
How many acetyl CoAs per glucose enter into the TCA cycle?
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
What topoisomerase makes ssDNA cuts, requires no ATP, relaxes supercoils, and acts as the swivel in front of the replication fork?
Topoisomerase I (Relaxase)
In prokaryotes, what is the name of the RNA sequence that ribosomes bind to so translation can occur?
Shine-Dalgarno sequence
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?
Autosomal recessive
What factors are needed for translation in prokaryotes?
Elongation factor-G and GTP
What three AAs must patients with maple syrup urine disease not eat?
Isoleucine, leucine, and valine
How many high-energy bonds are used to activate an AA?
2 ATPs, via the amino acyl tRNA synthase enzyme
What water-soluble vitamin deficiency results in pellagra?
Niacin (B3)
What glycolytic enzyme has a high Vmax, high Km, and low affinity for glucose?
Glucokinase
How many ATPs are generated per acetyl coenzyme A (CoA)?
12 ATPs per acetyl CoA that enter the tricarboxylic acid (TCA) cycle (Krebs cycle)
What cytoplasmic pathway produces NADPH and is a source of ribose 5-phosphate?
HMP shunt
What is the main inhibitor of pyruvate dehydrogenase?
Acetyl CoA (pyruvate to acetyl CoA)
Where on the codon and anticodon does the wobble hypothesis take place?
3'end of the codon (third position) on mRNA and 5' end of the anticodon (first position) on tRNA.
What DNA excision and repair enzyme is deficient in patients with xeroderma pigmentosum?
Excision endonuclease, which removes thiamine dimers from DNA
What form of bilirubin is carried on albumin?
Unconjugated (indirect)
What are the two ketogenic AAs?
Leucine and lysine
Which organisms have polycistronic mRNA?
Prokaryotes. Polycistronic and prokaryotes both start with P.
As what compound do the carbons for fatty acid synthesis leave the mitochondria?
Citrate, via the citrate shuttle
What four substances increase the rate of gluconeogenesis?
1. Glucagon
2. NADH
3. Acetyl CoA
4. ATP
With what three enzymes is thiamin pyrophosphate (TPP) associated?
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
What test uses very small amounts of DNA that can be amplified and analyzed without the use of Southern blotting or cloning?
PCR
What apoprotein is required for the release of chylomicrons from the epithelial cells into the lymphatics?
apo B-48
What enzyme catalyzes the covalent bonding of the AA's carboxyl group to the 3' end of tRNA?
Aminoacyl-tRNA synthetase, which uses 2 ATPs for this reaction.
What must be supplemented in patients with medium-chain acyl CoA dehydrogenase (MCAD) deficiency?
Short-chain fatty acids
What form of AA is found only in collagen?
Hydroxyproline
In a diabetic patient, to what does aldose reductase convert glucose?
Sorbitol (resulting in cataracts)
What enzyme catalyzes the rate-limiting step in cholesterol metabolism?
HMG-CoA reductase
What is the term for the pH at which the structure carries no charge?
pI (isoelectric point)
What enzyme catalyzes the rate-limiting step in gluconeogenesis?
Fructose-1, 6-bisphosphatase
What is the drug of choice in treating a patient with hyperuricemia due to underexcretion of uric acid?
Probenecid, a uricosuric agent
What enzyme deficiency results in darkening of the urine when exposed to air?
Homogentisate oxidase deficiency is seen in patients with alcaptonuria.
In eukaryotes, what transcription factor binds to the TATA box before RNA polymerase II can bind?
Transcription factor IID
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?
Primase
What enzyme catalyzes the rate-limiting step in fatty acid synthesis?
Acetyl CoA carboxylase
Name the eukaryotic DNA polymerase based on the following information:
• Replicates mitochondrial DNA
DNA polymerase-γ
Name the eukaryotic DNA polymerase based on the following information:
• Synthesizes the lagging strand during replication
DNA polymerase-α
Name the eukaryotic DNA polymerase based on the following information:
• Synthesizes the leading strand during replication
DNA polymerase-δ
What is the order of fuel use in a prolonged fast?
1. Glucose from liver glycogen
2. Glucose from gluconeogenesis
3. Body protein
4. Body fat
Which way will the O2 dissociation curve shift with the addition of 2, 3-bisphosphoglycerate (2, 3-BPG) to adult hemoglobin (Hgb)?
Shifts it to the right
What enzyme of pyrimidine synthesis is inhibited by the following?
• 5-FU
Thymidylate synthase
What enzyme of pyrimidine synthesis is inhibited by the following?
• Methotrexate
Dihydrofolate reductase
What enzyme of pyrimidine synthesis is inhibited by the following?
• Hydroxyurea
Ribonucleotide reductase
What is found in the R group if the AA is acidic? Basic?
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.
What gluconeogenic mitochondrial enzyme requires biotin?
Pyruvate carboxylase
What factors are needed for translocation in eukaryotes?
EF-2 and GTP
DNA replication occurs during what phase of the cell cycle?
S phase
What is the end product of purine catabolism?
Uric acid
What causes transcription to stop in eukaryotes?
The poly(A) site on the DNA
What enzyme of the TCA cycle catalyzes the production of the following:
• FADH2
Succinate dehydrogenase
What enzyme of the TCA cycle catalyzes the production of the following:
• GTP
Succinyl CoA synthetase
What enzyme of the TCA cycle catalyzes the production of the following:
• NADH (hint: 3 enzymes)
Isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and malate dehydrogenase
What form of alcohol causes blindness?
Methanol (wood alcohol)
How many base pairs upstream is the prokaryotic TATA box promoter?
There are two bacterial promoter regions upstream. The TATA box is - 10 base pairs upstream, and the -35 promoter site is self-explanatory.
What are the two essential fatty acids?
Linoleic acid and linolenic acid
During a prolonged fast, why is the brain unable to use fatty acids?
Fatty acids cannot cross the blood-brain barrier; therefore, they cannot be used as an energy source.
What type of jaundice is seen in Rotor's syndrome?
Conjugated (direct) hyperbilirubinemia
If a sample of DNA has 30% T, what is the percent of C?
Solved as 30% T + 30% A = 60%; therefore, C + G = 40%; then C = 20% and G = 20% (example of Chargaff's rule)
From where is the energy for gluconeogenesis derived?
β-Oxidation of fatty acids
Name the type of mutation:
• The deletion or addition of a base
Frameshift
Name the type of mutation:
New codon specifies a different AA
Missense
Name the type of mutation:
• Unequal crossover in meiosis with loss of protein function
Large segment deletions
Name the type of mutation:
• New codon specifies for the same AA
Silent
Name the type of mutation:
• New codon specifies for a stop codon
Nonsense
What form of bilirubin can cross the blood-brain barrier?
Unconjugated free bilirubin
What AA is broken down into N2O, causing an increase in cyclic guanosine monophosphate (cGMP) of smooth muscle, hence vasodilation?
Arginine
What three things are needed to produce a double bond in a fatty acid chain in the endoplasmic reticulum?
NADPH, O2, and cytochrome b5
What are the vitamin K–dependent coagulation factors?
Factors II, VII, IX, X, and proteins C and S
Is the hydroxyl (–OH) end of DNA and RNA at the 3' or the 5' end?
3' end. Phosphate (PO4) is at the 5' end.
How many codons code for AAs? How many for termination of translation?
61 codons code for AAs and 3 codons (UAA, UGA, UAG) code for the termination of translation.
What is the enzyme for the oxidative reaction in glycolysis?
Glyceraldehyde dehydrogenase
What substrate builds up in Tay-Sachs disease?
GM2 ganglioside

Caused by a deficiency of β-hexosaminidase A
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?
Mitochondrial inheritance
What is the rate-limiting enzyme of glycogen synthesis?
Glycogen synthase
What sphingolipid is formed by the union of serine and palmitoyl CoA?
Sphingosine
What causes an increase in bone mineralization and Ca2+ along with PO4- absorption from the GI tract and kidney tubules?
Vitamin D
What two sugars can be used to produce cerebrosides?
Glucose and galactose
What group of eukaryotic regulatory proteins has a major factor in controlling the gene expression embryonically?
Homeodomain proteins
What causes the lysis of RBCs by oxidizing agents in a G-6-PD deficiency?
The lack of glutathione peroxidase activity results in a decrease in NADPH production, leaving glutathione in the reduced state.
All AAs have titration plateaus at what pH values?
pH of 2 and 9
What cytoplasmic organelle carries the enzymes for elongation and desaturation of fatty acyl CoA?
SER
What is the binding site for RNA polymerase?
The promoter indicates where transcription will begin.
What vitamin is necessary for epithelial health?
Vitamin A is responsible for vision and epithelial health.
What lipoprotein is formed if an IDL particle acquires cholesterol from a HDL particle?
LDL
What structure of a protein describes the interaction among subunits?
Quaternary structure
What is the only factor of enzyme kinetics that the enzyme affects?
Ea (activation energy)
Is the Lac operon activated or inactivated in the presence of both glucose and lactose?
Inactivated; glucose results in decreased cAMP levels and therefore blocks protein binding between cAMP and CAP.
At the end of each round of β-oxidation, what is released?
Acetyl CoA, FADH2, and NADH
What is the rate-limiting enzyme on glycolysis?
Phosphofructokinase-1 and costs 1 ATP
What enzyme of heme synthesis is deficient in the autosomal dominant disorder acute intermittent porphyria?
Uroporphyrinogen-I synthase
What enzyme is blocked by disulfiram?
Aldehyde dehydrogenase
Deficiencies in what enzyme result in insoluble glycogen synthesis formation?
α-1, 6 transferase
What eukaryotic translation enzyme is associated with the following:
• Initiation
eIF-2 in the P site
What eukaryotic translation enzyme is associated with the following:
• Elongation
eEF-1
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.
What AA undergoes N-glycosylation?
Asparagine
What is the pyrimidine intermediate that joins PRPP (5-Phosphoribosyl-1-Pyrophosphate)?
Orotic acid
(purine metabolism)
What intermediate of cholesterol synthesis anchors proteins in the membranes and forms CoA?
Farnesyl pyrophosphate (FPP)
What AA is a phenol?
Tyrosine
What hormone is activated in adipose tissue when blood glucose levels decrease?
Hormone-sensitive lipase
How many NADPHs are used per addition of acetyl CoA into a fatty acid chain?
2 NADPHs per acetyl CoA
What factors are needed for elongation in eukaryotes?
EF-1 and GTP
What purine base is contained in inosine monophosphate?
Hypoxanthine (remember, IMP is a precursor for AMP and GMP)
What are the two ways that nitrogen can enter into the urea cycle?
Aspartate and carbomoyl PO4-
What two requirements must be met for the Lac operon to be activated?
Lactose must be present and glucose must be absent
Name the phase of the eukaryotic cell cycle:
• Period of cellular growth (translation and transcription) before DNA synthesis
G1 phase (gap 1)
Name the phase of the eukaryotic cell cycle:
• Period of cellular growth (translation and transcription) after DNA synthesis
G2 phase (gap 2)
Name the phase of the eukaryotic cell cycle:
• Period of DNA replication (preparing for mitosis)
S phase
Name the phase of the eukaryotic cell cycle:
• Cells cease replicating (i.e., nerve cell)
G0 phase
True or false? RBCs anaerobically use glucose in both the well-fed and fasting states.
True. Remember, RBCs do not contain mitochondria, so they cannot metabolize aerobically.
What enzyme of the TCA cycle catalyzes the substrate level phosphorylation?
Succinyl CoA synthetase
What apoprotein on HDL activates lecithin–cholesterol acyltransferase (LCAT)?
apo A-1
What three AAs are used to synthesize the purine ring?
1. Glycine
2. Aspartate
3. Glutamine
How many ATPs are produced from cytoplasmic NADH oxidation using the glycerol phosphate shuttle?
2 ATPs by oxidative phosphorylation
What enzyme is deficient in patients with PKU?
Phenylalanine hydroxylase
What three steps of the TCA cycle generate NADH?
1. Malate dehydrogenase
2. Isocitrate dehydrogenase
3. α-Ketoglutarate dehydrogenase
What two enzymes of heme synthesis are inhibited by lead?
ALA dehydrogenase and ferrochelatase
What enzyme, induced by insulin and activated by apo C-II, is required for chylomicron and VLDL metabolism?
Lipoprotein lipase
What is the most common genetic deficiency resulting in hemolytic anemia?
G-6-PD deficiency; pyruvate kinase deficiency is second.
Are the following conditions associated with a negative or positive nitrogen balance?
• AA deficiency
Negative
Are the following conditions associated with a negative or positive nitrogen balance?
• Growth
Positive
Are the following conditions associated with a negative or positive nitrogen balance?
• Pregnancy
Positive
Are the following conditions associated with a negative or positive nitrogen balance?
• Uncontrolled DM
Negative
Are the following conditions associated with a negative or positive nitrogen balance?
• Starvation
Negative
Are the following conditions associated with a negative or positive nitrogen balance?
• Infection
Negative
Are the following conditions associated with a negative or positive nitrogen balance?
• Recovery from injury
Positive
Are the following conditions associated with a negative or positive nitrogen balance?
• Kwashiorkor
Negative
Why is the liver unable to metabolize ketone bodies?
Hepatocytes lack the enzyme succinyl CoA acetoacetyl CoA transferase (thiophorase).
What toxin ADP-ribosylates via Gs protein to increase cAMP?
Cholera toxin
What two vitamins are inactivated when they come in contact with acetaldehyde?
Thiamine and folate
Name the end product or products:
• Fatty acid synthesis
Palmitate
Name the end product or products:
• Fatty acid oxidation
Acetyl CoA and propionyl CoA (in odd chain fatty acids)
What is the term for production of a DNA copy from an RNA molecule?
Reverse transcription
What two monosaccharides are produced when lactose is hydrolyzed?
Galactose and glucose
What mineral is required for cross-linking of collagen molecules into fibrils?
The enzyme lysyl oxidase requires Cu2+and O2 to function properly.
What blotting technique uses the following for analysis?
• DNA
Southern blot
What blotting technique uses the following for analysis?
• Protein
Western blot
What blotting technique uses the following for analysis?
• RNA
Northern blot
How many high-energy bonds does the cycle of elongation cost?
Four high energy bonds, two from ATP in AA activation and two from GTP
What enzyme of purine synthesis is inhibited by allopurinol and 6-mercaptopurine?
PRPP aminotransferase
True or false? The urea cycle takes place in both the cytoplasm and the mitochondria.
True. Remember, carbamoyl phosphate synthetase and ornithine transcarbamoylase are mitochondrial enzymes.
What is the only fatty acid that is gluconeogenic?
Propionic acid
What enzyme has a 5' to 3' synthesis of the Okazaki fragments, 3' exonuclease activity, and 5' exonuclease activity?
DNA polymerase I
In what organelle does the TCA cycle occur?
Mitochondria
Do genomic or cDNA libraries contain introns, exons, promoters, enhancers, and are they fragmented?
Genomic libraries are made from nuclear DNA, are fragmented, and contain all sequences found in the particular genome copied.
What enzyme is deficient in selective T cell immunodeficiency?
Purine nucleoside phosphorylase
True or false? Adipose tissue lacks glycerol kinase.
True. Adipose depends on glucose uptake for dihydroxyacetone phosphate (DHAP) production for triglyceride synthesis.
In what form is excess folate stored in the body?
N-5-methyl THF
What is the term for taking an mRNA molecule and arranging the AA sequence forming a protein?
Translation
What enzyme is blocked by hydroxyurea?
Ribonucleotide reductase
What protein carries free fatty acids to the liver?
Albumin
What substrate is built up in Niemann-Pick disease?
Sphingomyelin
True or false? Methylation of bacterial DNA prevents restriction endonuclease from cutting its own chromosomes.
True. Restriction endonucleases cut only unmethylated DNA.
What two AAs have a pKa of 10?
Lysine and tyrosine
What is the only enzyme in the body that uses N-5-methyl folate?
Homocysteine methyl transferase
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.
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)
Is the coding or the template strand of DNA identical to mRNA (excluding the T/U difference)?
The coding strand is identical to mRNA, and the template strand is complementary and antiparallel.
What enzyme is deficient in acute intermittent porphyria?
porphobilinogen deaminase
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)
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
To what does aldose reductase convert galactose?
Galactitol
Name three purine bases that are not found in nucleic acids.
Xanthine, hypoxanthine, theophylline, theobromine, caffeine, and uric acid are all purines.
What water-soluble-vitamin deficiency is associated with cheilosis and magenta tongue?
Riboflavin (B2)
What is the precursor of all sphingolipids?
Ceramide
What three substances stimulate glycogenolysis?
1. Ca2+ : calmodulin ratio
2. Epinephrine
3. Glucagon
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.
What factors are needed for elongation in prokaryotes?
EF-Tu or EF-ts and GTP
What restriction endonuclease site is destroyed in sickle β-globin allele?
MstII; changing codon 6 (from A to T) destroys the restriction site.
What complex is needed for propionyl CoA carboxylase?
Biotin, ATP, and CO2
What enzyme catalyzes the reversible oxidative deamination of glutamate and produces the TCA cycle intermediate α-ketoglutarate?
Glutamate dehydrogenase
What enzyme is deficient in congenital erythropoietic porphyria?
Uroporphyrinogen III cosynthase
What is the drug of choice for treating a patient with hyperuricemia due to overproduction of uric acid?
Allopurinol
What is the maximum rate possible with a given amount of enzyme?
Vmax
From what do catalase, superoxide dismutase, and glutathione peroxidase defend the cell?
Production of oxygen free radicals
What signals are used to direct an enzyme to a lysosome?
Phosphorylation of mannose residues
What enzyme catalyzes the rate-limiting step of the urea cycle?
Carbamoyl phosphate synthetase I
What liver enzyme, for triglyceride synthesis, converts glycerol to glycerol-3-phosphate?
Glycerol kinase
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
What pattern of inheritance does G-6-PD deficiency follow?
X-linked recessive
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)
Via what cell surface receptor does HDL cholesterol from the periphery enter hepatoceles?
Scavenger receptor (SR-B1)
Which shuttle is used to bring fatty acyl CoA from the cytoplasm for ketogenesis?
Carnitine acyl CoA transferase II
What enzyme is blocked by 5-FU?
Thymidylate synthetase
What disease has a genetically low level of UDPglucuronate transferase, resulting in elevated free unconjugated bilirubin?
Gilbert's syndrome
What AA has a pKa of 13?
Arginine
What X-linked recessive disorder is characterized by hyperuricemia, spastic cerebral palsy, mental retardation, and self-mutilation?
Lesch-Nyhan syndrome
How many ATPs per glucose are generated from glycolysis in RBCs?
2 ATPs, because RBCs use only anaerobic metabolism.
What enzyme catalyzes the rate-limiting step in glycogenolysis?
Glycogen phosphorylase
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.
As what AAs do muscles send nitrogen to the liver?
Alanine and glutamine
What sphingolipid cannot be produced without sialic acid and amino sugars?
Ganglioside
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)