UNE BIOCHEMISTRY MIDTERM STUDY GUIDE QUESTIONS FULLY SOLVED & UPDATED 2023

A 19-year-old boy is diagnosed with Creutzfeldt-Jakob disease which is caused by the introduction of an amyloid fold in the disease-causing protein. The introduction of this fold causes the protein to transition from a primarily alpha helical structure to an aggregate of mostly beta sheets. This change in protein structure (leading to disease) is best attributed to changes in which of the following? folding of the secondary structures Which of the following is the best description of primary protein structure? a newly synthesized strand of amino acids How do most enzymes reduce the activation energy needed to move a reaction forward? providing an active site most complementary the transition state Movement of ammonia from an amino acid to an a-keto acid involves a family of enzymes best categorized as which of the following? transferases Hemoglobin has the ability to display cooperative binding while myoglobin does not display this binding kinetic pattern. Which of the following differences between the two proteins accounts for this difference in binding kinetics? the presence of quaternary structure Changes in the physiological variables listed below can alter the affinity of hemoglobin for oxygen. Which of the following will lower the affinity of hemoglobin for oxygen? increase in 2,3 bisphosphoglycerate (BPG) An enzyme has a mutation within the substrate binding site that reduces the binding of the coenzyme needed for covalent catalysis. Which of the following is likely to result as a consequence of this mutation? the enzyme will not be able to form the transition state complex Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as which of the following classes of enzymes? hydrolases If a mutation is made within the active site of an enzyme resulting in a decrease in Km, which of the following will be true with respect to the enzyme kinetics? the enzyme will require a lower substrate concentration to reach 1/2 Vmax Which of the following best describes an enzyme inhibitor that increases the Km but does not change the Vmax? a competitive inhibitor An enzyme is participating in a general acid-base catalysis reaction with an optimal reaction pH of 6.0. If acid is added to the environment reducing the pH to 3, what is the Iikely impact to the rate of the reaction? the rate of the reaction is likely to decrease as the pH is out of optimal catalytic range A new enzyme is discovered that increases in activity when it is phosphorylated on an exposed tyrosine residue. Phosphorylation of this amino acid is classified as which of the following? covalent modification In the image below the blue line indicates enzyme kinetics with no inhibitor present. Based on this information, which of the following is true? the green line shows enzyme kinetics with the addition of a noncompetitive inhibitor An example of enzyme activation by cleavage is best illustrated by which of the following? activation of chymotrypsinogen to chymotrypsin Use the figure below to compare the activities of glucokinase and hexokinase. Based on this information, which of the following is a true statement? glucokinase has a higher Km than hexokinase The following represents a series of reactions. As levels of B increase, this will decrease the conversion of S3 to B. Which of the following best describes this type of regulation in a biosynthetic pathway? feedback inhibition ATP is used to carry energy within the cell. The majority of energy in ATP is stored within which of the following bonds indicated on the image below? 1 Which os the following describes a correct and complete electron transfer pathway necessary for oxidative phosphorylation? NADH-- complex 1 -- CoQ-- complex III --cyt c -- complex IV Which of the following components of the electron transport chain is not bound to the mitochondrial membrane? CoQ ATP is a high energy molecule that is often hydrolyzed during reactions. The energy within ATP is stored primarily in which of the following components of the molecule? in the high energy phosphate bonds Heat can be generated in the brown adipose tissue of hibernating mammals. Which of the following is the most likely mechanism by which this occurs? expression of a protein that uncouples the ETC Succinate is a substrate for which complex in the electron transport chain? Complex II (Succinate-Q reductase) Which of the following is a true statement with regards to the malate-aspartate shuttle system? generates 2.5 molecules of ATP in mitochondria per each NADH from glycolysis Which of the following would be consistent with an exergonic reaction? delta G0 would be negative Complex II (Succinate Q-reductase) is not considered to be part of the process of oxidative phosphorylation because it is unable to do which of the following activities? pump protons from the mitochondrial matrix to the intermembrane space Dinitrophenol is an uncoupler of the electron transport chain. The addition of dinitrophenol will have which of the following impacts? increase oxygen consumption A 19-year-old male is being evaluated for muscle weakness. Evaluation of a muscle biopsy revealed normal rates of succinate oxidation but very low rates of pyruvate oxidation. Further testing determined normal levels of enzymatic activity in both malate dehydrogenase and pyruvate dehydrogenase. Based on this data, the patient may have a mutation in a gene encoding for which mitochondrial protein? Complex I (NADH Q-oxidoreductase) The malate-asparate shuttle is used to move reducing equivalents of cystolic NADH into the mitochondria where it can be oxidized. Which of the following compounds is used to move the reducing equivalents from cystolic NADH into the mitochondria? malate A series of reaction have the following delta G: A+B-- G=-1; C+D-- E G=+3 and E+F--G G=-5.... the overall delta G for this series of reactions is determined to be which of the following values? -3 An alpha-helical arrangement of amino acids is considered to be what level of protein structure? secondary structure of the protein Which amino acid would not be commonly found in the middle of an alpha-helical domain? proline Which of the following best describes a protein domain? a section of protein structure sufficient to perform a particular chemical or physical task Allosteric activators of hemoglobin will increase substrate binding through which of the following mechanisms? binding the protein, and keeping it in the "R" conformation Which of the following best describes the structure of heme? a planar porphyrin ring that binds iron Which of the following is an example of enzyme regulation through covalent modifcation? phosphorylation of muscle glycogen phosphorylase Under low energy conditions, AMP will bind to phosphofructokinase I and glycogen phosphorylase at site unique to the active site. This enhances the activity of these enzymes. This is an example of which of the following types of enzyme regulation? allosteric activation A 28-year-old male is recently diagnosed with HIV. As part of his treatment he is prescribed Nevirapine which interferes with retroviral reverse transcriptase enzyme. Using the graph below, which of the following best describes the impact of this drug on its target? It reduces the catalytic activity of the enzyme