WGU Biochemistry Questions and Answers All Verified and Rated A+

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WGU Biochemistry Questions and Answers All Verified and Rated A+ A risk factor associated with the use of metformin in the treatment of diabetes is lactic acidosis. Acidosis is associated with [a d... ecrease] in blood pH, due to [an increase] in the concentration of hydrogen ions (H+). Given this change in blood pH, hemoglobin is more likely to [release] oxygen. Correct Answer- Acidosis is associated with a decrease in blood pH, due to an increase in the concentration of hydrogen ions (H+). Given this change in blood pH, hemoglobin is more likely to release oxygen. A small segment of Kevin's green opsin gene is shown below. What would be the resulting mRNA sequence? Kevin's opsin gene at nucleotide positions 936 to 941. 5'-G.C.C.T.A.G-3' (coding strand) 3'-C.G.G.A.T.C-5' (template strand) c. 5'-GCCUAG-3' Correct Answer- This sequence is the same as the coding sequence, and the "T" bases have been replaced with "U", as is found in RNA. A substrate binds to an enzyme at a specific site, referred to as a(n)_________________. b. Active site Correct Answer- The active site of an enzyme is the site where the substrate specifically binds to the enzyme and the reaction is carried out. Acetyl-CoA, a central molecule in metabolism, is produced in the mitochondrial matrix. However, it is used for the synthesis of fatty acids in the cytosol. The transport of the acetylCoA from the matrix to the cytosol occurs by the conversion of acetyl-CoA to_______________.a. citrate Correct Answer- Acetyl-CoA combines with oxaloacetate to produce Citrate. Note that citrate is the first product produced in the citric acid cycle by the same reaction. Cells have the ability to mobilize citrate across the mitochondrial membrane. Thus, acetyl-CoA moves out of the mitochondria to the cytosol in the form of citrate. Once in the cytosol, the citrate is converted back to oxaloacetate and acetyl-CoA, and acetyl-CoA is utilized in fatty acid synthesis. Addition of ______________________alters the shape of the iron-heme complex, and therefore its absorption of light as indicated by its color change from dark purple (the color of hemoglobin in venous blood) to brilliant scarlet (the color of hemoglobin in arterial blood). c. oxygen Correct Answer- Oxygen binding alters the shape of the iron-heme complex, and therefore its light absorption properties as indicated by a color change. Aerobic respiration requires oxygen. Oxygen has a role in which of the following pathways: b. Electron transport chain Correct Answer- Gluconeogenesis is building of new glucose molecules and is not involved in aerobic respiration. Oxygen has a role as the terminal electron acceptor in the electron transport chain. After consultation with a genetic counselor and an examination of extended family history, the following pedigree was generated. Who did Kevin most likely inherit this mutation from? a. Maternal grandfather Correct Answer- Red-green color blindness occurs more frequently in males than females because these genes are located on the X chromosome, and males inherit only one X chromosome and will express whatever alleles are on that chromosome. Females, on the other hand, inherit two X chromosomes, and thus have two alleles for each gene. If one of the alleles is mutated on one X chromosome, there is usually a correct allele on the other that can provide the needed gene. A woman must have two mutated opsin alleles to be color blind, while men need only one. This is known as sex-linked inheritance. Kevin inherited his Y chromosome from his father and his X chromosome from his mother, so his X chromosome with the defective opsin gene most likely came from his maternal grandfather and was passedto him by his mother. Thus, both grandfathers is not correct because his paternal grandfather would have contributed a Y chromosome. After learning about Alzheimer's disease and one of the drugs used in its treatment, what other drug design strategies could you use to offer a treatment for AD? a. Drugs that block the production of amyloid beta peptide b. Drugs that break up the amyloid plaques d. Drugs that inhibit the aggregation of protein structures Correct Answer- The more we are able to understand the molecular details of a disease and the enzymes involved in the disease pathway, the more opportunities one has to target the key molecules. Any of the options here could be a possible treatment in the case of AD. Alzheimer's disease is caused by aggregation of the Amyloid beta peptide and tangle formation by the tau protein. What kinds of amino acids are likely to drive the formation of these protein aggregates? c. Hydrophobic Correct Answer- Hydrophobic amino acids strive to avoid water and like to interact with other hydrophobic amino acids. Generally they are found in the interior of a protein. But, when there are too many misformed peptides with exposed hydrophobic surfaces, they tend to attract each other and result in protein aggregation. As carbon monoxide binds to hemoglobin, the protein subunits change conformation to allow carbon monoxide to bind faster. This process is called __________. d. positive cooperativity Correct Answer- Carbon monoxide does competitively inhibit the overall function of the hemoglobin protein. Note that the question is referring to how the binding of one carbon monoxide molecule influences the conformation of the other subunits and increases the overall binding affinity for the hemoglobin molecule. Such a cooperative behavior exhibited by the subunits is referred to as positive cooperativity.Below is a diagram of the four steps of the beta oxidation cycle. Drag the correct small molecule to the step in the pathway to which it contributes. Correct Answer- The four steps of beta oxidation each involve a small molecule other than the fatty acid in the process, as shown below: Below is a schematic showing the synthesis and degradation of acetylcholine, an important neurotransmitter. If you were to design a drug to keep the acetylcholine concentration high, where would you target a drug inhibitor? b. Acetylcholinesterase Correct Answer- Acetylcholine is the substrate of the reaction and the desired chemical to preserve. However, since acetylcholine does not control its own production, it is ideal to target enzymes that can impact its concentration. Enzymes that produce acetycholine could be targeted for increased production, but this type of regulation is difficult to achieve with a drug. Instead, drugs usually inhibit specific enzymes. Acetylcholinesterase is the enzyme which digests acetylcholine to acetate and choline. Acetylcholinesterase inhibition will decrease degradation of the acetylcholine, which will therefore increase the concentration of acetylcholine. Supplementation with excess acetate or choline may also help increase choline acetyltransferase activity and perhaps increase acetylcholine concentrations, but the only productive target for a drug inhibitor in this scheme is acetylcholinesterase. Beta oxidation of a C14 fatty acid will make_______________ acetyl-CoA units after________ rounds of beta-oxidation. a. seven, six Correct Answer- Each round of beta-oxidation results in the production of a twocarbon acetyl-CoA units, so the number of carbons in a fatty acid chain divided by two is how many acetyl-CoA units are made. The number of rounds needed is one less than the number of acetyl-CoA units produced because the last round of beta-oxidation produces two acetyl-CoA units. Thus, a C14 fatty acid will altogether make seven acetyl-CoA units after six rounds of beta oxidation. Blood type is an example of what type of inheritance?a. Codominance Correct Answer- The genes that produce the A and B antigen proteins can both be expressed independently, and a heterozygote (someone with both genes) will be produce both A and B proteins - neither will dominate the other. The is an example of codominance. Carbohydrate loading is a common practice among endurance athletes. Often, three days before a big endurance event, they are known to eat large amounts of complex carbohydrates which leads to the storage of glycogen in their muscles. The stored glycogen increases their endurance by providing a steady supply of glucose during the event by the process of _______________. d. glycogenolysis Correct Answer- Glycogenolysis is the breakdown of glycogen to release glucose. A further breakdown of glucose results in ATP production which helps with the prolonged physical activity in the athletes. Carbon monoxide outcompetes oxygen for attachment to the __________ group of hemoglobin where it is permanently, covalently attached. d. heme Correct Answer- Carbon monoxide has a higher binding affinity than oxygen to the heme group of hemoglobin. Such binding is irreversible. Carbon monoxide shifts the Oxygen-Hemoglobin Dissociation Curve to the left, while carbon dioxide shifts this curve to the right. Based on your knowledge of the Bohr Effect, which of the following statements is true? b. Carbon dioxide decreases hemoglobin's affinity for oxygen, while carbon monoxide increases it Correct Answer- Carbon dioxide, released by the respiring cells, combines with the water molecules of plasma to form carbonic acid. Carbonic acid increases the H+ ion concentration (low or acidic pH). H+ ions stabilize the deoxy-conformation (T state) of hemoglobin and allow oxygen release and delivery to the tissues. On the other hand, carbon monoxide, which has a very high affinity for hemoglobin than oxygen, binds and maintains hemoglobin in oxyconformation (R state). Oxy-conformation of HB is amenable to further binding of carbon monoxide and shifts the Oxygen-Hemoglobin Dissociation Curve to the left.Carbonic anhydrase is an important __________ present in the red blood cells that aids in efficient transportation of carbon dioxide in the form of _________, from tissues to lungs. b. enzyme, bicarbonate ions Correct Answer- Carbonic anhydrase is an enzyme which catalyzes the conversion of carbon dioxide to bicarbonate ions. However, it does not transport carbon dioxide as is, but rather transports carbon dioxide by converting it to bicarbonate ions. This mechanism enables efficient transport of carbon dioxide by warding off bubble formation in the blood. Cyanide binds to complex IV of the electron transport chain, preventing electron transport. Which of the following would be the most immediate effect(s) of cyanide consumption a. Oxygen would not be consumed by the ETC. b. ADP will build up c. Protons will not be pumped to the intermembrane space Correct Answer- Cyanide binds to the last complex of the electron transport chain, complex IV, which usually transfers electrongs to oxygen to create water and keep the flow of electrons going. By blocking complex IV, oxygen will not be consumed, which will prevent electron transport. As a result, NADH cannot be consumed by the ETC and will build up, and protons cannot be pumped into the intermembrane space of the mitrochondria. As a result, ATP production by ATP synthase will slow. Deedra's dad has Alzheimer's Disease (AD) which is caused by a change in ______ structure. d. protein Correct Answer- AD is a manifestation of neuronal death and damage caused by malformed protein structures. Proteins are crucial molecules with various functions in the cells. The structure of a protein directly impacts its function. Deedra's father has Alzheimers which is caused by a disturbance in the protein structure of at least two proteins, amyloid beta and tau.DNA replication is ___________, which allows each of the two strands to serve as a _______ for the new strands. b. semiconservative, template Correct Answer- DNA replication is semiconservative, meaning that each new duplex has one original (parent) strand and one new strand. Because the two parent strands are separated during replication and the base pairing is predictable, each parent strand can serve as a template for the new strand synthesis. Drag the name of the protein structure level to the part of the amino acid that primarily contributes to that structure level. Correct Answer- Correct! The backbone of the amino acid participates primarily in primary and secondary structure while the R group stabilizes tertiary and quaternary structure. Due to their amphipathic nature, phospholipids can form micelles and transport other lipids. The fatty acid chains that make up the phospholipids are the basis for their non-polar character, and the __________ is/are the basis of its polar nature. d. phosphate group Correct Answer- Phospholipids have a phosphate group attached to the glycerol backbone that is the basis for their polar characteristic. During periods of strenuous exercise the muscle cells can become anaerobic. Without oxygen, the electron transport chain cannot continue and the citric acid cycle slows down. In such situations, how do cells make ATP? a. Pyruvate is transformed to lactate. Correct Answer- In the absence of oxygen, pyruvate is reduced to form lactic acid by fermentation. Emma has an A1C level of 7.0% in her blood. A1C is a form of__________________. a. Hemoglobin Correct Answer- In the presence of excessive amounts of glucose in the blood, glucose makes a covalent bond to the hemoglobin protein in a reaction known as glycation. A1C is the glycated form of hemoglobin.Emma was prescribed metformin which is used to control blood glucose levels. One direct effect of metformin is inhibition of the ------------------------- pathway in the liver. c. Gluconeogenesis Correct Answer- Metformin is a drug of choice for treating Type 2 diabetes. One of the direct actions of the drug in controlling the blood sugar levels is by inhibiting gluconeogenesis in the liver. Fatty acid synthesis occurs in the ---, so its building block molecule acetyl-CoA must be transported out of the --- and into the --- using the --- transport system. The acetyl-CoA is then combined with --- with the help of the coenzyme molecule --- in order to form --- in the first committed step of fatty acid synthesis. Correct Answer- The correct answer is: Fatty acid synthesis occurs in the [cytosol], so its building block molecule acetyl-CoA must be transported out of the [mitochondria] and into the [cytosol] using the [citrate] transport system. The acetylCoA is then combined with [carbon dioxide] with the help of the coenzyme molecule [biotin] in order to form [malonyl‑CoA] in the first committed step of fatty acid synthesis. Glucose is a monosaccharide. It can be used as the raw material to build which one of the following molecules? d. Glycogen Correct Answer- Glycogen is a polysaccharide made up glucose units. Glucose is not the only food source that can make acetyl Co-A. Correct Answer- Various sources such as amino acids and fatty acids, in addition to glucose, can be catabolized to produce acetyl Co-A. Glycolysis is the conversion of glucose to pyruvate. Is this a catabolic process or an anabolic process? d. Catabolic Correct Answer- Anabolic pathways refer to the synthesis of larger molecules from smaller ones, and they often require energy input from ATP.Catabolic pathways refer to the breakdown of larger molecules into smaller ones and often produce ATP as a result. Glycolysis is a catabolic process. During glycolysis, a molecule of glucose is broken down into two molecules of pyruvate and two molecules of ATP are made in the process. Hemoglobin acts as a buffer and controls the pH of the blood by binding to __________. d. H+ ions. Correct Answer- H+ ions contribute to the acidity of blood. By binding to these ions, hemoglobin is able to act as a buffer and maintain the pH at an appropriate range. Hemoglobin consists of four protein subunits. Each subunit contains [a heme group] that holds [an iron atom], which can bind to [an oxygen moleule]. Correct Answer- Hemoglobin protein consists of four protein subunits. Each subunit contains a heme group which binds an iron atom. The iron binds to oxygen, which can then be transported by hemoglobin. Hemoglobin's ability to bind or release oxygen depends on the pH of the environment. This behavior is known as the Bohr effect. Considering this, which of the following statements is true? a. Hemoglobin binds to the oxygen at high pH and releases oxygen at low pH. Correct AnswerpH is a measure of H+ ion concentration. High pH indicates a more basic environment in which the H+ ion concentration is low, as seen in the lungs. Under these conditions, hemoglobin binds more oxygen. Low pH indicates an acidic environment in which the H+ ion concentration is high. Such conditions encourage the binding of H+ ions to hemoglobin and stabilizing a form of hemoglobin which decreases the affinity for oxygen, resulting in release of oxygen. Hemoglobin's cooperative binding behavior is key to its physiological function. The binding of which of the following molecules influences this behavior? b. Oxygen Correct Answer- Binding of the first oxygen molecule to a hemoglobin subunit greatly enhances binding of the remaining oxygen molecules. All subunits communicate with each other and work in a unified fashion. This property is referred to as cooperativity.How many hydrogens can be accommodated by the carbon (in bold) that is participating in the double bond: -C-C=C-Ca. One Correct Answer- Recall that carbon can form four bonds. The carbons that are participating in a double bond will bind to one hydrogen each. Notice that four out of three bond positions are already occupied by the carbon-carbon bonds. If Zoey continues on her path of a no-fat diet, she could have a very poor wound healing response. Which one of the following lipid molecules can have an affect on this response? a. Phospholipid Correct Answer- Recall that phospholipids are crucial for cell membrane structure and fluidity. Additionally, in response to certain hormonal signals, certain fatty acids in the phospholipids are released from the cell membranes to produce other key lipid molecules such as eicosanoids. Eicosanoids play several roles in inflammation, fever, immunity and blood coagulation. In an exercising muscle cell under anaerobic conditions, Incorrect from glycolysis is turned into - -- in order to regenerate --- for further rounds of glycolysis, which produces --- ATP per round for the muscle cell to use. The Cori cycle allows --- to be turned into --- via gluconeogenesis in the liver at the expense of --- ATP. This means that, overall, the Cori cycle creates a deficit of --- ATP. Correct Answer- In an exercising muscle cell under anaerobic conditions, [pyruvate] from glycolysis is turned into [lactate] in order to regenerate [NAD+] for further rounds of glycolysis, which produces [2] ATP per round for the muscle cell to use. The Cori cycle allows [lactate] to be turned into [glucose] via gluconeogenesis in the liver at the expense of [6] ATP. This means that, overall, the Cori cycle creates a deficit of [4] ATP. In comparison to adult hemoglobin, fetal hemoglobin has a [higher] affinity for oxygen because it [doesn't bind] 2,3-BPG well. Correct Answer- Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin because its structure does not bind 2,3-BPG well. As a result, the T state of fetal hemoglobin is not stabilized and it remains more readily in the R state, ready to bind oxygen even at lower concentrations.In human cells, glycolysis takes place in the cytoplasm. The products of the glycolysis will enter the _________________ to continue with aerobic respiration. b. mitochondria Correct Answer- The products of glycolysis enter the mitochondria to continue with aerobic respiration. In Kevin's case, a specific kind of mutation in the opsin gene resulted in the premature termination of the translation process. This resulted in a shorter opsin protein than usual. What specific mutation could have caused this? c. Nonsense mutations Correct Answer- Missense mutations are point mutations that change a single base pair in a codon such that the codon now encodes a different amino acid. In Kevin's case, a nonsense mutation, which is a point mutation that changes a single base pair in a codon to a stop codon resulted in termination of the translation signal. This further led to the synthesis of truncated protein. In locations where the pH is low, hemoglobin will be in the [T] state, allowing it to [release] oxygen more effectively. Correct Answer- At low pH, hemoglobin will be in the T, or tense, state to allow it to release oxygen more effectively to oxygen-starved tissues. In order to fulfill their function, proteins must fold in proper, three-dimensional conformations. Which one of the following molecules, available in a cell, is likely to help a protein fold properly? b. Chaperone Correct Answer- Chaperones are helper proteins that ensure proper protein folding by stabilizing the polypeptide until the correct structure is fully formed. In the enzymatic cycle, the enzyme shape is changed when [Substrate binds] and resumes its original shape when [Product is released] after [Substrate is converted to product]. Correct Answer- An enzyme is a catalyst, meaning that it can catalyze the same reaction over and over again. Substrate binding can alter the conformation (or shape) of an enzyme, so it must resume its original shape when product is released, after substrate is converted to product, to allow it to perform the same reaction again.In the lungs, the CO2 concentration is [low] and the pH is [high], while in the tissues, the CO2 concentration is [high] and the pH is [low]. Correct Answer- In the lungs, CO2 concentration are low, resulting in decreased carbonic acid and higher pH. This creates a more basic (or alkaline) environment that promotes oxygen binding.In the tissues, CO2 concentration tends to be high, resulting in increased carbonic acid which lowers the pH. This creates an acidic environment that promotes oxygen release. In the pathway above, what will happen to the levels of Second Intermediate Substrate if Enzyme 1 is inhibited as a result of feedback inhibition? c. Decrease Correct Answer- Inhibition of an enzyme earlier in the pathway will prevent the product(s) of that enzyme from forming, thereby preventing the action of subsequent enzymes and formation of their respective products. For example, inhibition of Enzyme 1 would lead to a decrease in First Intermediate Substrate, which then reduces the levels of Second Intermediate Substrate because Enzyme 2 has less substrate on which to act. Thus, the levels of Second Intermediate Substrate will decrease as a result of feedback inhibition. In the pathway above, which compound could accumulate and trigger feedback inhibition? c. End Product Correct Answer- The substrate is the start of the pathway, and therefore cannot inhibit anything before itself. While the amount of substrate could be reduced, and thereby slow product formation, the substrate itself is not part of feedback inhibition. In order to regular the amount of a product from a pathway, cells often use feedback inhibition. When the end product is no longer needed (or needed at a reduced rate), the product begins to accumulate and bind to enzymes in the pathway. This binding can inhibit the action of that enzyme by noncompetitive inhibition, thus slowing the pathway and reducing the amount of product made. In the presence of oxygen, the end products of glycolysis have the potential to enter which one of the following pathways?c. Citric acid cycle Correct Answer- In the presence of oxygen, pyruvate forms acetyl Co-A and enters the citric acid cycle, while fermentation occurs in the absence of oxygen. Increased levels of 2,3-BPG will [decrease] the affinity for oxygen by binding to and stabilizing the [T] state of hemoglobin. The action of 2,3-BPG allows hemoglobin to [release] oxygen more effectively, which is similar to the effect of [low] pH on the action of hemoglobin. Correct Answer- Increased levels of 2,3-BPG will Incorrect the affinity for oxygen by binding to and stabilizing the Correct state of hemoglobin. The action of 2,3-BPG allows hemoglobin to Incorrect oxygen more effectively, which is similar to the effect of Correct pH on the action of hemoglobin. [Show More]

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