WGU C785 Final Exam With All The Correct Answers Already Passed

WGU C785 Final Exam With All The Correct Answers Already Passed Which level of protein structure is disrupted through the hydrolysis of peptide bonds? Quaternary Tertiary Primary Secondary Correct Answer: P ...

WGU C785 Final Exam With All The Correct Answers Already Passed Which level of protein structure is disrupted through the hydrolysis of peptide bonds? Quaternary Tertiary Primary Secondary Correct Answer: Primary The primary structure of a protein is the sequence of amino acids held together by peptide bonds. Peptide bonds are formed by dehydration reactions and disrupted by hydrolysis. A mutation in the beta-hemoglobin gene, which results in the replacement of the amino acid glutamate in position 6 with the amino acid valine, leads to the development of sickle cell anemia. The structures of glutamate and valine are shown below. If the beta hemoglobin gene in a patient with sickle-cell anemia were to be edited so that the valine in position 6 was replaced with a different amino acid, which replacement for valine would be expected to have the best clinical outcome, in theory, for the patient? (Assume the valine can potentially be replaced with any amino acid other than glutamate.) Correct Answer: The original amino acid in a healthy patient is glutamate, which is negatively charged. The mutated amino acid is valine, which is non-polar. Valine is causing sickle cell anemia. The best amino acid to replace valine so that the patient is healthy again would be the one most like glutamate, so any negatively charged amino acid. Secondary, tertiary, and quaternary levels of protein structure can all be impacted by exposing a protein to which treatment? Change of a hydrophobic amino acid to a different hydrophobic amino acid Addition of a reducing agent Placement of the protein in a solution with a low pH Increase in the concentration of the protein in solution Correct Answer: Placement of the protein in a solution with a low pH Changes in pH affect hydrogen bonds and ionic bonds. Hydrogen bonds in the backbone of amino acids occur in secondary structure, and both hydrogen bonds and ionic bonds occur in the side chains of amino acids in tertiary structure. An increase in beta-pleated sheet structure in some brain proteins can lead to an increase in amyloid deposit formation, characteristic of some neurodegenerative diseases. What is the primary biochemical process that follows the increase in beta-pleated sheet structure that leads to the development of the amyloid deposits? An increase in glycogen formation in the brain cells Aggregation of the proteins in the brain Secretion of glucagon, leading to excessive ketogenesis An increase in anaerobic metabolism of glucose in the brain Correct Answer: Aggregation of the proteins in the brain This question is describing changes in protein structure. Aggregation occurs when proteins clump together inappropriately, causing plaques like amyloid deposits to accumulate. Which level of protein structure is determined by the sequence of amino acids? Secondary structure Quaternary structure Tertiary structure Primary structure Correct Answer: Primary structure The primary structure of a protein is simply the sequence of amino acids held together by peptide bonds. Which force is most influential in determining the secondary structure of a protein? Hydrophobic effect Disulfide bonding Hydrogen bonding Electrostatic interactions Correct Answer: Hydrogen bonding The secondary structure of a protein is built by hydrogen bonds between the carboxyl groups and amino groups on the backbones of the amino acids. Which amino acid would most likely participate in hydrogen bonds? Correct Answer: Amino Acid structure 4 This is a polar, uncharged amino acid due to the OH group on the side chain. Polar, uncharged amino acids containing oxygen or NH groups make hydrogen bonds. Which portion of the amino acid is inside the box? The box is surrounding the section below the Alpha Carbon Correct Answer: Side Chain The side chain is the variable group of the amino acid, also called the R group. Every amino acid has the same amino group, carboxylic acid group, and an alpha carbon, but the side chain is different. Which pair of amino acids will most likely interact through hydrophobic forces between their side chains? Correct Answer: Both of these amino acids are non-polar and therefore can interact together with a hydrophobic interaction. Please note that the "S" in the amino acid on the right is non-polar, while the "SH" group in answer choice D is polar. The S must have an H to be polar and is otherwise non-polar. Which portion of the amino acid is inside the box? The box is over the Carbon at the Center of the chain Correct Answer: Alpha Carbon The alpha carbon is the central carbon on an amino acid that holds together the other groups of the amino acid. It is always attached to the amino group, the carboxyl group, the side chain, and a single hydrogen. It is part of the backbone of the amino acid and is found in every amino acid. Given the following amino acid structure, what is the strongest intermolecular force it would participate in to stabilize a protein structure? Ionic bond Disulfide bond Hydrogen bond Hydrophobic interaction Correct Answer: Hydrophobic interaction The amino acid pictured only has CH groups in its side chain, and therefore is non-polar. Non-polar amino acids make hydrophobic interactions. Which change would most likely result in a permanent modification of an expressed protein's function? An increase in the pH of a solution in which a protein is dissolved from 6.5 to 8.0, when it is known that the protein has an optimal activity of pH 7.8 A mutation of the gene for a protein that leads to the substitution of a hydrophobic amino acid with a nonpolar amino acid A mutation of the gene for a protein that leads to the substitution of a nonpolar amino acid with a charged amino acid The mutation of a gene for an enzyme involved in protein synthesis following exposure to X-rays, causing the protein not to be synthesized Correct Answer: A mutation of the gene for a protein that leads to the substitution of a nonpolar amino acid with a charged amino acid. The mutation of nonpolar amino acid to a charged amino acid will disrupt the original hydrophobic interaction, permanently changing the function of the protein. Which property of enzymes is illustrated in the final step of the enzymatic cycle? Enzymes are specific. Enzymes increase the reaction rate for a reaction. Enzymes are reusable. Enzymes lower the activation energy for a reaction. Correct Answer: Enzymes are reusable. In the final step of the enzymatic cycle, the product is released and the enzyme is able to bind to a new substrate and begin the cycle again. In the enzyme cycle, which step immediately follows induced fit? Formation of the enzyme-substrate complex Release of the product and enzyme complex Formation of the enzyme-molecule complex Formation of the enzyme-product complex Correct Answer: Formation of the enzyme-product complex The induced fit refers to the conformational change that the enzyme undergoes when it binds to the substrate to form the enzyme-substrate complex. Therefore, the enzymatic cycle step that occurs after the induced fit is the formation of the enzyme-product complex. Which type of inhibition occurs when a particular drug binds to the active site of an enzyme? Competitive Uncompetitive Irreversible Noncompetitive Correct Answer: Competitive Competitive inhibitors compete with the substrate to bind to the active site of the enzyme. Salivary amylase, an enzyme responsible for partial digestion of carbohydrates, has optimum activity at a pH value of 6.8. What is the impact on the activity if the pH is decreased to 4.0? Significantly increase Significantly decrease Slightly decrease Slightly increase Correct Answer: Significantly decrease A drop in pH from 6.8 to 4.0 is a significant change in pH. Recall that the hydrogen bonds and ionic bonds that hold protein structures together can be broken by changes in pH. The disruption in protein structure due to this pH change will also significantly decrease amylase activity. Low levels of glutathione are associated with certain types of ovarian and breast cancers. In the synthesis of glutathione, glutathione accumulates in the cell, binding to an enzyme in the pathway and temporarily preventing the synthesis of glutathione. Which type of inhibition is described by this scenario? Feedback Competitive Allosteric Uncompetitive Correct Answer: Feedback The keywords here are that glutathione accumulates and binds to an enzyme in the pathway to prevent synthesis. Feedback inhibition occurs when a product of a pathway turns into an inhibitor of an enzyme earlier in the pathway. Lipase is an enzyme with an optimum temperature of 98.6°F and an optimum pH of 7.0 in the duodenum in the human body. If a person is experiencing a fever of 99.8°F, what will increase the activity of the lipase enzyme? Decrease in temperature Increase in temperature Decrease of the substrate of the enzyme Increase of pH of duodenum to 8.0 Correct Answer: Decrease in temperature An enzyme will have the highest activity when it is under optimal conditions. In this case, the fever of 99.8 is above the optimal temperature, so lowering the temperature will increase activity. The enzyme glucokinase only binds its substrate glucose and converts glucose into the product glucose-6-phosphate. Which property of enzymes is described by this scenario? Specificity Activation energy Induced fit