D1201-1400 Flashcards
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?
- 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?
- 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?
Uroporphyrinogen I synthetase
What five cofactors and coenzymes are required by pyruvate dehydrogenase?
- 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?
- 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?
- 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?
- 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?
- 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?
- 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
