C785 Final Biochem Exam Fully Solved & Updated.

Which mRNA sequence results in a polypeptide that contains three amino acids? - ANSWER-5' - CUU GAU ACU UAG - 3' Which RNA sequence would end in the following polypeptide? Phe-Thr-Val-Stop - ANSWER-5' - UUC ACA GUA UAA - 3' What is the complementary sequence for the following DNA sequence? 5' - GCC ATC TCG AAT - 3' - 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? - ANSWER-16 What is the function of DNA polymerase in the process of PCR? - 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? - 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? - ANSWER-GAA to GTA What are possible blood types of the parents of a patient with blood type AB? - ANSWER-A and B Which pair of chromosomes accurately depicts the genotype of a person with an autosomal recessive mutant HBB allele and sickle cell anemia? - ANSWER-option 3- 2 mutant genes on chromosome 11 Which pair of chromosomes accurately depicts the genotype of a person with an X-linked recessive mutant ALAS2 allele and sideroblastic anemia? - ANSWER-option 3, mutated allele 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? - 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. 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? - 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? - 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? - ANSWER-The mutation rate of all other genes is higher due to failure to repair. Which reaction is responsible for the formation of polypeptides? - ANSWER-Dehydration Which portion of the amino acid is inside the box? - ANSWER-Carboxyl group Which amino acid side group is polar? - ANSWER-option 2-one with charge When placed within a polypeptide chain, which amino acid would interact most favorably with nonpolar amino acids? - ANSWER-option 2-non polar Which term describes the order of amino acids in a peptide chain? - ANSWER-Primary structure When using heat to denature a protein, which force is the first to be disrupted as temperature increases? - 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? - 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? - ANSWER-Protein aggregation In which situation would altering a protein structure lead to a disease state? - ANSWER-A mutation in aconitase blocks an essential step in aerobic metabolism How can an alteration in protein structure lead to a disease state? - 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. Which structural level shows the greatest difference when replacing denatured proteins with a denatured single subunit protein? - ANSWER-Tertiary 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? - ANSWER-Hydrophobic interactions form between denatured egg white proteins. What is the driving mechanism of plaque formation in prion diseases? - 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? - 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? - 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? - 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? - ANSWER-It has a high affinity for oxygen. At low O 2 concentrations, how does myoglobin's affinity for O 2 relate to hemoglobin's affinity for O 2? - ANSWER-Myoglobin has a much greater affinity for O 2 than hemoglobin does. Which pair of binding curves accurately compares how hemoglobin and myoglobin become saturated with oxygen as a function of the partial pressure of oxygen? - ANSWER-option 2 How does pH level promote the deoxygenated conformation of hemoglobin? - ANSWER-When pH lowers, O 2 binds with excess HCO 3 - in the blood, which blocks its ability to bind to the heme group and pull it into the dome conformation. What is occurring in surrounding tissues as the amount of hemoglobin saturated with oxygen increases? - ANSWER-The amount of carbon dioxide decreases. What is feedback inhibition? - ANSWER-Reversible, noncompetitive inhibition of an enzyme in a pathway by a product of that pathway Which form of enzyme regulation is likely to be used by an organism to control the catalytic activity of its enzymes as it adapts to changes in available nutrients? - ANSWER-Feedback inhibition How does heating beyond optimum temperature inactivate enzymes? - ANSWER-By changing the enzyme's three-dimensional shape What occurs in enzymes during the phenomenon of induced fit? - ANSWER-Substrate binding causes a conformational change. Which portion of the enzyme does the substrate bind to? - ANSWER-Active site Based on the provided enzyme pathway below, what would occur as a result of a defect in the enzyme which catalyzes the D→E reaction? - ANSWER-The amount of C would increase. Which type of inhibition occurs when a particular drug binds to the allosteric site of an enzyme and subsequently changes the enzyme's structure - ANSWER-Non competitive A particular enzyme acts on the succinate substrate and is inhibited by malonate. Which type of inhibition is expected based on the following structures? - ANSWER-Competitive What occurs immediately after the appropriate molecule enters the active site of an enzyme? - ANSWER-The enzyme binds the molecule to form an enzyme-molecule complex. Which type of inhibition is depicted in the following reaction scheme? - ANSWER-Feedback inhibition Which type of inhibition is depicted in the following figure? - ANSWER-non competitive How is energy provided for ATP production during the final stage of aerobic metabolism? - ANSWER-Protons diffuse through a transmembrane protein. How does insulin impact carbohydrate metabolism? - ANSWER-It stimulates the uptake of glucose from the blood by cells in the body. How does insulin reduce blood glucose levels? - ANSWER-It increases the translocation of GluT4 transporters to the cell membrane. Approximately how many ATP molecules can be produced from a single molecule of glucose during aerobic metabolism? - ANSWER-30 Which cellular condition prompts the cell to perform fermentation rather than the citric acid cycle? - ANSWER-Lack of O 2 What causes the symptoms of noninsulin-dependent (Type 2) diabetes? - ANSWER-There are not enough GluT4 transporters on plasma membranes. How many molecules of acetyl-CoA will the following fatty acid produce? - ANSWER-8 Which metabolic pathway involves coenzyme A, NAD, and FAD? - ANSWER-Beta oxidation Which molecule is pyruvate directly converted to under aerobic conditions? - ANSWER-Acetyl-CoA How many molecules of lactate are required to produce one molecule of glucose? - ANSWER-2 What is the role of oxygen in aerobic metabolism? - ANSWER-It acts as the final electron acceptor in the electron transport chain Which pathway is triggered by increased levels of epinephrine and provides a quick increase in available glucose? - ANSWER-Glycogenolysis Which type of molecule can be used in gluconeogenesis? - ANSWER-Amino acids Which molecule acts as the primary signal for glycogen breakdown? - ANSWER-Glucagon What is a possible chemical formula for a monounsaturated fatty acid? - ANSWER-C 8 H 14 O 2 Which carbon atom is the omega-carbon in the following fatty acid? - ANSWER-1 Which molecule represents the structural formula CH 3(CH 2) 4CH = CH(CH 2) 4COOH? - ANSWER-option 1 What is the correct chemical formula of the following fatty acid? - ANSWER-CH 3(CH 2) 5CH = CH(CH 2) 2COOH What is the function of the class of lipids known as eicosanoids? - ANSWER-They act as signaling molecules. What is a glycolipid? - ANSWER-A polymer of monosaccharides covalently attached to a membrane lipid. Which component of red blood cells determines blood type in the ABO blood group system? - ANSWER-Glycolipids and glycoproteins Which vitamin is not absorbed by phospholipid micelles? - ANSWER-Vitamin C Which event is stimulated by release of glucagon into the blood? - ANSWER-Increase in lipolysis of triglycerides What occurs in an otherwise healthy person whose diet has very few carbohydrates and high levels of fats? - ANSWER-Acetone is produced in the blood.