WGU C785 Biochemistry Unit Exam Questions and Answers 100% Verified

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WGU C785 Biochemistry Unit Exam Questions and Answers 100% Verified A final product of a four-step metabolic pathway serves as a noncompetitive inhibitor, binding to an enzyme in this pathway and t... emporarily turning off the pathway. Which enzyme is most likely to be targeted by the inhibitor? The final enzyme in the pathway The first enzyme in the pathway Any enzyme in the middle of the pathway The second enzyme in the pathway Correct Answer- The first enzyme in the pathway The final product's structure is more unlike the substrate for the first enzyme in the pathway than any other, and thus the least likely to fit the active site of enzyme 1. 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 AnswerThe 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.A patient has received a large dose of ionizing radiation at his place of employment. Which scenario is accurate? Ligase removes a single damaged base and replaces it with a new nucleotide. Double-stranded DNA breaks are being repaired by nonhomologous end joining, without the use of a homologous template. The homologous recombination pathway is upregulated and is facilitating the removal of mismatched bases. A string of damaged nucleotides is removed and replaced by a new nucleotide sequence in the base excision repair pathway. Correct Answer- Double-stranded DNA breaks are being repaired by nonhomologous end joining, without the use of a homologous template. Due to the large dose of ionizing radiation, the patient has many double-stranded DNA breaks, and undamaged homologous DNA is in short supply. Nonhomologous end-joining will be used to fix these double-strand breaks. A point mutation has altered the amino acid sequence of a neuronal tau protein, causing serine (Ser) at position 202 to be mutated to proline (Pro). Which set of codons below corresponds to this mutation? TCT to CCT AGA to GGA CGA to AGG AGG to CCC Correct Answer- TCT to CCTTCT is a codon for Ser, and CCT is a codon for Pro. TCT to CCT is a point mutation that changes Ser to Pro. A portion of the HLA gene and its associated amino acid sequence are shown below. If cytosine is deleted from codon 101, what will be the resulting amino acid sequence? Ser Tyr Glu Glu Met Leu Glu Pro Cys Glu His Ala Asp Correct Answer- Glu Met Leu Deletion of cytosine (C) from codon 101 leads to the DNA sequence 5'-GAG ATG CTG AT-3', which corresponds to the amino acid sequence Glu Met Leu. 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 ketogenesisAn 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. During aerobic metabolism, acetyl-CoA is produced from which molecule? Glycerol Lactate Pyruvate Oxaloacetate Correct Answer- Pyruvate Acetyl-COA is produced from the breakdown of pyruvate after glycolysis. During gluconeogenesis, how many ATP molecules are consumed for each glucose molecule produced? 4 2 1 6 Correct Answer- 6It takes 6 ATP molecules to produce glucose through gluconeogenesis. 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. Nonpolar amino acids make hydrophobic interactions. Hemoglobin acts as a buffer to prevent blood from becoming too acidic by binding ___. excess bicarbonate excess oxygen excess H+ excess CO2 Correct Answer- excess H+H+ causes blood pH to drop and become acidic. Hemoglobin binds to H+ which not only causes O2 to be released to the tissues but also buffers the blood to allow the pH to increase. How does the activation energy of enzyme-catalyzed reactions compare to those of corresponding uncatalyzed reactions? The activation energy of enzyme-catalyzed reactions are the same as uncatalyzed reactions The activation energy of the enzyme-catalyzed reactions only changes in response to temperature. The activation energy of enzyme-catalyzed reactions are lower than the uncatalyzed reaction The activation energy of enzyme-catalyzed reactions are higher than uncatalyzed reactions Correct Answer- The activation energy of enzyme-catalyzed reactions are lower than the uncatalyzed reaction The activation energy is the amount of energy needed to get the reaction started and over the energy hill to form products. Enzymes reduce the amount of energy needed to start the reaction or lower the amount of energy needed to climb the energy hill. How does the proton gradient affect the pH of the mitochondrial matrix and the intermembrane space? The concentration of protons in the matrix is higher than the concentration in the intermembrane space. The concentration of protons in the intermembrane space is higher than the concentration in the matrix.The pH of the intermembrane space is higher than the pH of the matrix. The pH of the intermembrane space is higher than the pH of the cytoplasm. Correct AnswerThe concentration of protons in the intermembrane space is higher than the concentration in the matrix. The intermembrane space of mitochondria has a high concentration of hydrogen ions (H+) which makes the pH very low compared to the matrix. Identify the factors that favor the deoxygenated form of hemoglobin. Excess protons, high carbon dioxide Excess protons, low carbon dioxide Few protons, low carbon dioxide Few protons, high carbon dioxide Correct Answer- Excess protons, high carbon dioxide Favoring deoxygenated hemoglobin means oxygen is being delivered or released from hemoglobin. When the tissues are using O2 to make ATP, CO2 is a byproduct. As CO2 accumulates in the blood it is converted to bicarbonate and H+ (protons). It's the build-up of H+ that lowers the pH and also initiates the release of oxygen from hemoglobin. Thus, high CO2 means excess H+, lower pH, and delivery of O2. If a fish raised in cold water were moved to much warmer water, how would it alter its membrane phospholipids? Membrane phospholipids would include the same fatty acids under either condition.Membrane phospholipids would include more shorter-chain, unsaturated fatty acids. It would add more cholesterol to its membranes. Membrane phospholipids would include more longer-chain, saturated fatty acids. Correct Answer- Membrane phospholipids would include more longer-chain, saturated fatty acids. The key to this question is to understand the relationship between the physical/chemical properties of fatty acids and the fluidity of membranes. An important thing to understand about cell membranes is that they are fluid. They are neither solid nor liquid, really, but something in between, almost like a gel. This fluidity allows the things in the membrane, such as membrane proteins, cholesterol, and phospholipids to move around and this movement is essential for staying alive. If we were to suddenly move a goldfish (for example) from freezing water (0 degrees Celsius) to a summertime pond (say, 25 degrees Celsius), that would be a huge problem. This is because the membrane lipids that were appropriately fluid at 0 C will now be TOO liquid at the warmer 25 C. The same is true going the other way too. A membrane that was appropriately fluid at 25 C would suddenly 'freeze-up' and become too solid at 0 C. The bulk of the material that makes up our cell membranes are the fatty acids that are part of the phospholipids from which the membrane is made. We can get a good idea of how temperature will affect membrane fluidity if we remember how temperature affects fatty acid fluidity. A basic relationship you will want to remember is this: The longer a fatty acid molecule is, the higher its melting point. The more double bonds it has, the lower it's melting point. What this means for membrane fluidity is this: When it's warm outside, and we want our membrane not to get too "runny", we want to make our phospholipids with more saturated, longer chain fatty acids. By contrast, when it is colder, we want to use more shorter-chain and unsaturated fatty acids in our phospholipids to keep our membrane from freezing solid. If a person were eating an absolutely fat-free diet, which vitamins would he or she not get enough of? Vitamins A, D, E, and KVitamins A, C, E, and K Vitamins A, B, C, and D Vitamins A, C, D, and K Correct Answer- Vitamins A, D, E, and K It is important to recall that there are just four fat-soluble vitamins. All the other vitamins that we need in our diet are water-soluble molecules. The fat-soluble vitamins are A, D, E, and K. If we consume no fats in our diet, we will have no source for these vitamins, since they come in along with the fat we consume. Immediately following transcription, mRNA must be processed before it is transported to the cytoplasm to undergo translation. Which statement correctly describes mRNA processing? Alternative combinations of introns can be linked together to produce closely related gene products. Exons are removed and introns are inserted into the mature mRNA sequence. mRNA is folded into beta-pleated sheets and alpha helices to produce a mature mRNA sequence. Introns are spliced out and exons are connected to produce a mature mRNA sequence. Correct Answer- Introns are spliced out and exons are connected to produce a mature mRNA sequence. Introns are removed from the mRNA sequence and the remaining exons are spliced together to create the mature mRNA. 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. In which situation would altering a protein structure lead to a disease state? A mutation in starch can lead to increased blood glucose levels. A mutation in cholesterol can result in heart disease. A mutation in an omega-3 fatty acid can cause a skin rash. A mutation in acetyl-CoA carboxylase can lead to brain damage. Correct Answer- A mutation in acetyl-CoA carboxylase can lead to brain damage. Acetyl-CoA carboxylase is an enzyme, and enzymes are proteins. We know this is an enzyme because the name ends in "-ase".Inheriting mutations in the BRCA-1 or BRCA-2 gene can increase an individual's likelihood of developing breast cancer or ovarian cancer. How can PCR be used to assess an individual's susceptibility to developing these cancers? PCR can be used to produce the mRNA for the BRCA-1 and BRCA-2 genes, which can then be sequenced to look for mutations. PCR primers can be engineered to flank the mutation of interest in the BRCA-1 and BRCA-2 genes, and the PCR product can be sequenced to look for mutations. The PCR process will provide an exponential increase in the amino acid sequence of the gene products. Then the amino acid can be sequenced to look for mutations. PCR primers can be engineered to sequence the BRCA-1 and BRCA-2 genes and determine whether mutations are present. Correct Answer- PCR primers can be engineered to flank the mutation of interest in the BRCA-1 and BRCA-2 genes, and the PCR product can be sequenced to look for mutations. By using primers that flank the mutation of interest, PCR can produce DNA which can be used to determine if the mutation is present. Legumain is an enzyme that is overexpressed in neurons in response to traumatic brain injury (TBI). How does TBI trigger an increase in the expression of the gene that codes for legumain? Nucleosomes are more widely spaced, exposing the legumain gene. DNA polymerase is able to bind to the legumain gene. Nucleosomes become tightly packed together, preventing the binding of transcription factors to the promoter region of the legumain gene. [Show More]

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