BIOCHEM C785 Final Exam

BIOCHEM C785 Final Exam Which mRNA sequence results in a polypeptide that contains three amino acids? 5' - CUU GAU ACU UAG - 3' 5' - UAU GCC CUA CGA - 3' 5' - AUC CAG UAA AAG - 3' 5' - GUC UGA CAC CGG - 3' Corre ...

BIOCHEM C785 Final Exam Which mRNA sequence results in a polypeptide that contains three amino acids? 5' - CUU GAU ACU UAG - 3' 5' - UAU GCC CUA CGA - 3' 5' - AUC CAG UAA AAG - 3' 5' - GUC UGA CAC CGG - 3' Correct Answer: 5' - CUU GAU ACU UAG - 3' Which RNA sequence would end in the following polypeptide? Phe-Thr-Val-Stop 5' - UUC ACA GUA UAA - 3' 5' - UUU UAU GUU UGG - 3' 5' - UUC CAU UGA GUA - 3' 5' - AAU AUG ACA CUU - 3' Correct Answer: 5' - UUC ACA GUA UAA - 3' What is the complementary sequence for the following DNA sequence? 5' - GCC ATC TCG AAT - 3' 5' - CGG TAG AGC TTA - 3' 5' - ATT CGA GAT GGC - 3' 5' - TAA CGA GAT CCG - 3' 5' - CGG ATG TCG TTA - 3' Correct Answer: 5' - ATT CGA GAT GGC - 3' Assuming 100% reaction efficiency, how many DNA copies are created after the completion of four complete PCR cycles? 24 16 8 4 Correct Answer: 16 What is the function of DNA polymerase in the process of PCR? It separates the two DNA strands so that replication may occur. It recognizes the primers and uses the available dNTPs to replicate the template DNA sequence. It synthesizes primers and uses the available dNTPs to replicate the template DNA sequence. It links the products of PCR together to generate a complete strand. Correct Answer: It recognizes the primers and uses the available dNTPs to replicate the template DNA sequence. 5' - [...] ATT CGC TAG GGC [...] - 3' − Normal DNA 5' - [...] ATT CGC GAG GGC [...] - 3' − Mutant DNA Which type of mutation and outcome characterizes the Mutant DNA? A missense mutation leading to a longer protein A nonsense mutation leading to a longer protein A nonsense mutation leading to a shorter protein A missense mutation leading to a shorter protein Correct Answer: A missense mutation leading to a longer protein 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? GAA to GTA GAA to GAT GAC to GTC GGU to GTT Correct Answer: GAA to GTA What are possible blood types of the parents of a patient with blood type AB? A and A A and B B and O AB and O Correct Answer: A and B 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? The DNA bases are chemically modified with methyl groups. The nucleosomes become more widely spaced. Transcription factors have less access to the promoter region. RNA polymerase cannot bind better to the terminator region Correct Answer: The nucleosomes become more widely spaced. Mice with low levels of agouti gene expression tend to have yellow fur and are obese, while mice with higher levels of expression are brown and of normal weight. Studies show that expression of the agouti gene in mice can be controlled by epigenetics. What scenario describes epigenetic regulation of the agouti gene? Mother mice fed methyl-rich diets during pregnancy give birth to offspring with decreased agouti gene expression compared to those fed a methyl-poor diet. Mice with one allele in the agouti gene produce more agouti protein compared to mice with a different allele. A mother mouse exposed to radiation acquires a mutation in the agouti gene that makes a defective agouti protein in her offspring. A mouse that acquires a spontaneous mutation in a transcription factor is able to more easily activate the agouti gene than mice without the mutation. Correct Answer: Mother mice fed methyl-rich diets during pregnancy give birth to offspring with decreased agouti gene expression compared to those fed a methyl-poor diet. Oxidative damage to DNA can often result in the alteration of a single nucleotide. Which DNA repair mechanism would repair this type of damage? Base excision repair DNA photolyase repair Nucleotide excision repair Mismatch repair Correct Answer: Base excision repair 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? The mutated nucleotide excision gene products increase cell proliferation. The mutated nucleotide excision gene products induce a higher mutation rate in other genes. The mutation rate of all other genes is higher due to failure to repair. The mutation rate of all other genes is higher due to increased rates of thymine-dimer formation. Correct Answer: The mutation rate of all other genes is higher due to failure to repair. Which reaction is responsible for the formation of polypeptides? Dehydration Hydrolysis Oxidation Phosphorylation Correct Answer: Dehydration Which term describes the order of amino acids in a peptide chain? Primary structure Secondary structure Tertiary structure Quaternary structure Correct Answer: Primary structure When using heat to denature a protein, which force is the first to be disrupted as temperature increases? Hydrophobic interactions Ionic bonds Peptide bonds Disulfide bonds Correct Answer: Hydrophobic interactions A commonly used technique for protein denaturation is adding an acid or a base to dramatically change the pH. Which force is most impacted by this change in pH? Hydrophobic interactions Ionic bonds Peptide bonds Disulfide bonds Correct Answer: Ionic bonds 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? Glycogen depletion Protein aggregation Carbohydrate catabolism Oxygen deprivation Correct Answer: Protein aggregation In which situation would altering a protein structure lead to a disease state? A mutation in calcium phosphate results in weak bones A mutation in glycogen results in increased blood sugar levels A mutation in a triglyceride results in obesity A mutation in aconitase blocks an essential step in aerobic metabolism Correct Answer: A mutation in aconitase blocks an essential step in aerobic metabolism How can an alteration in protein structure lead to a disease state? A mutation replaces an isoleucine with an aspartic acid in a transcription factor protein, which blocks the normal folding of the protein and its function in the expression of certain genes. A valine is mutated to a leucine on a membrane channel protein, which disrupts a hydrogen bond and blocks transport of a nutrient into cells. A mutation replaces a cysteine with a methionine in an antibody protein, which disrupts a critical ionic bond and results in immunodeficiency. A glutamic acid is mutated to a proline in the active site of an enzyme, which results in the loss of a critical disulfide bond needed for catalysis and blocks a step in metabolism. Correct Answer: A mutation replaces an isoleucine with an aspartic acid in a transcription factor protein, which blocks the normal folding of the protein and its function in the expression of certain genes. Frying an egg changes the egg white from a clear liquid to an opaque solid. Which molecular change in the albumin protein causes this change in appearance? Hydrophobic interactions form between denatured egg white proteins. A change in the pH of the egg white causes the proteins to turn white. The thiol groups in the egg white proteins are cross linked by disulfide bonds. The ionic bonds of the egg white proteins are disrupted. Correct Answer: Hydrophobic interactions form between denatured egg white proteins. What is the driving mechanism of plaque formation in prion diseases? An increase in the local pH in the brain tissue Propagation of misfolding from one protein to another A decrease in hydration in the brain tissue Genetic mutation that affects protein expression Correct Answer: Propagation of misfolding from one protein to another Which feature of a protein made of a single polypeptide chain is most directly responsible for its function? Complete lack of mutations Quaternary conformation Primary sequence Three-dimensional structure Correct Answer: Three-dimensional structure How does the Bohr effect describe the relationship between carbon dioxide levels, blood pH and the amount of oxygen bound to hemoglobin? An increase in carbon dioxide production leads to a decrease in blood pH, causing hemoglobin to release oxygen more readily. An increase in carbon dioxide production leads to an increase in blood pH, causing hemoglobin to release oxygen more readily. A decrease in carbon dioxide production leads to a decrease in blood pH, causing hemoglobin to release oxygen more readily. A decrease in carbon dioxide production leads to an increase in blood pH, causing hemoglobin to release oxygen more readily. Correct Answer: An increase in carbon dioxide production leads to a decrease in blood pH, causing hemoglobin to release oxygen more readily. Which statement describes the binding of oxygen gas to a heme group? The binding of oxygen gas to heme changes the structure of the heme group. Oxygen gas binds to heme with greater affinity than other gas molecules. Oxygen gas binds directly to the four porphyrin nitrogen atoms in the heme group. Up to four oxygen gas molecules can bind to each heme group. Correct Answer: The binding of oxygen gas to heme changes the structure of the heme group. Which characteristic of myoglobin makes it an effective oxygen storage molecule? CONTINUES...