C785 Biochemistry preassessment Exam Questions And Answers

Assuming 100% reaction efficiency, how many DNA copies are created after the completion of four complete PCR cycles? - ANS 16 What is the function of DNA polymerase in the process of PCR? - ANS It recognizes the primers and uses the available dNTPs to replicate the template DNA sequence. What are possible blood types of the parents of a patient with blood type AB? - ANS A and B − Amino Acid Number Tyr Gly Thr Pro − Amino Acid Sequence TAC GGG ACA CCA − DNA Sequence What is the amino acid in position 118 that results from a single nucleotide insertion immediately following the three guanines that encode for glycine 116? - ANS Thr In sickle-cell disease, the glutamic acid (Glu) at position number seven is mutated to valine (Val). What change in codons corresponds to this mutation? - ANS GAA to GTA Which type of mammalian DNA damage repair requires the presence of the chromosome that is homologous to the damaged chromosome? - ANS Recombination Xeroderma pigmentosum (XP) is a recessive genetic disease that occurs when one or more of the genes that perform nucleotide excision repair are nonfunctional. Why do XP patients have a much higher incidence of skin cancer than the general population? - ANS The mutation rate of all other genes is higher due to failure to repair. Which mRNA sequence results in a polypeptide that contains three amino acids? - ANS 5' - CUU GAU ACU UAG - 3' Which template strand DNA sequence would result in the amino acid (Ser)? - ANS 5' - CGA - 3' What is the complementary sequence for the following DNA sequence? 5' - GCC ATC TCG AAT - 3' - ANS 5' - ATT CGA GAT GGC - 3' Studies have shown that increased expression of two genes called SIRT1 and SIRT2 is associated with chronic exposure to cocaine and contributes to drug addiction. What difference in the regions of the SIRT1 and SIRT2 genes in people addicted to cocaine increases their expression? - ANS The nucleosomes become more widely spaced. What occurs during the process of alternative splicing of mRNA? - ANS Alternate combinations of exons within the same gene are linked together. Which force is most influential in determining the tertiary structure of a protein? - ANS Hydrophobic effect Given the following amino acid structure, what is the strongest intermolecular force it would participate in to stabilize a protein structure? - ANS Hydrogen bond What is the name of large, functional protein structures composed of smaller proteins with multiple subunits - ANS Quaternary structure Which structural level shows the greatest difference when replacing denatured proteins with a denatured single subunit protein? - ANS Tertiary Which level of protein structure is established through the dehydration synthesis of peptide bonds? - ANS primary Which situation would most likely lead to a permanent alteration of protein function? - ANS A mutation that substitutes a hydrophobic amino acid with a hydrophilic amino acid Given the following amino acid structure, what is the strongest intermolecular force it would participate in to stabilize a protein structure? - ANS hydrogen bond What is the name of large, functional protein structures composed of smaller proteins with multiple subunits? - ANS quarternary structure Pepsin, the enzyme that catalyzes the breaking of peptide bonds, has the highest activity in the acidic environment of the stomach. What process is disrupted after a patient ingests excessive antacid that neutralizes the pH of the stomach? - ANS Protein catabolism An active elderly patient is becoming frequently disoriented, having trouble recalling her daily routine, and becoming aggravated easily. She forgets words and places and has difficulty recognizing her children. Which biochemical event is responsible for this patient's behavior? - ANS Protein aggregation In which situation would altering a protein structure lead to a disease state? - ANS A mutation in aconitase blocks an essential step in aerobic metabolism How does hemoglobin keep blood pH neutral during exercise? - ANS Deoxygenated hemoglobin binds to excess H +. What is occurring in surrounding tissues as the amount of hemoglobin saturated with oxygen increases? - ANS The amount of carbon dioxide decreases. What is occurring in surrounding tissues as the amount of hemoglobin saturated with oxygen increases? - ANS The concentration of hydrogen ions decreases. Identify the factors that favor the oxygenated form of hemoglobin. - ANS High pH, low carbon dioxide Which metal ion is bound to the porphyrin ring in hemoglobin? - ANS Iron Which feature of hemoglobin makes it an effective oxygen transport molecule? - ANS Its affinity for oxygen is regulated by pH. Which enzyme binding scenario best describes enzyme specificity and action? - ANS An enzyme binds one substrate or closely related substrates to catalyze only one reaction. How do the rates of enzyme-catalyzed reactions compare to those of corresponding uncatalyzed reactions? - ANS They are 10 6 to 10 12 times faster. Which change will likely increase the activity of an enzyme currently at optimal conditions? - ANS Significantly increasing substrate concentration What occurs immediately after the appropriate molecule enters the active site of an enzyme? - ANS The enzyme binds the molecule to form an enzyme-molecule complex. An inhibitor is added to the following hypothetical pathway, which results in an accumulation of compound C. Which enzyme is affected by the inhibitor? - ANS enzyme 3 What is a temporary modification to protein structure by kinases that alters enzyme function? - ANS Phosphorylation Acetylcholine is broken down to acetate and choline by an enzyme called acetylcholinesterase. Low levels of acetylcholine in the brain is associated with neurodegenerative disease. Which of the following medications could be used to treat neurodegeneration associated with low acetylcholine levels? - ANS A non-competitive inhibitor of acetylcholinesterase. Which type of inhibition occurs when a particular drug binds to the allosteric site of an enzyme and subsequently changes the enzyme's structure? - ANS Noncompetitive