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Biochem Exam 3 2024/2025 Questions With Completed & Verified Solutions.
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Biochem Exam 3 2024/2025 Questions With Completed & Verified Solutions.
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Biochem Exam 3 (Question Bank)What would be the diagnosis of someone with diabetic blood glucose levels and high insulin
levels, but no family history of diabetes? - ANS Type II Diabetes Mellitus (lifestyle diabetes)
What is the cause of Type II diabetes?
A. It is an auto-immune disorder that destroys the β-cells of the pancreas so the patient
produces less insulin than normal.
B. Patient has a genetic mutation that results in less insulin receptor being produced than
normal.
C. Patient has developed insulin resistance, where his/her insulin receptors do not recognize
the insulin her
body produces, likely due to his/her obesity.
D. There is no known cause, it can happen spontaneously. - ANS C. Patient has developed
insulin resistance, where his/her insulin receptors do not recognize the insulin her
body produces, likely due to his/her obesity.
Why would injections of insulin not help someone if type II diabetes if he/she has
hyperglycemia?
A. His/her body is already producing excess insulin but not responding to it.
B. His/her problem is with her insulin receptors responding to insulin.
C. Excess insulin will only exacerbate his/her insulin resistance.
D. All of the above. - ANS D. All of the above
Given the metabolic state of someone with type II diabetes, which of the following pathways
would you expect to be active in their cells (select all that apply)?
A. Glycolysis
B. Gluconeogenesis
C. β-oxidation
D. Amino acid degradation
E. Protein synthesis - ANS all of them
Given the metabolic state of someone with type II diabetes, what is the primary fuel source for
his/her cells currently?
A. Carbohydrates (glucose)
B. Fats
C. Proteins
D. It is a balance of all three - ANS B. fats
One major side effect of the herbal supplement, ephedrine, can be hot flashes and increased
perspiration due to increased thermogenesis, what is the likely cause of the heat production?
A. Increasing the activity of phosphfructokinase-1.
,B. Increasing the activity of the pyruvate dehydrogenase complex.
C. Increasing the activity of citrate synthase.
D. Increasing the activity of uncoupling proteins. - ANS D. Increasing the activity of uncoupling
proteins.
Would substituting fiber and complex carbohydrates (larger % cellulose) for the simple sugars
and starches (high sucrose and amylose/amylopectin) help someone with type II diabetes lose
weight, why?
A. Yes, because complex carbohydrates like cellulose are largely indigestible so they pass
through
the digestive tract without being absorbed.
B. Yes, cellulose contains less glucose residues than amylose or amylopectin.
C. Yes, because the fructose in sucrose is much more responsible for weight gain than the
glucose.
D. No, because cellulose, amylose, and amylopectin are all composed of glucose so it doesn't
matter. - ANS A. Yes, because complex carbohydrates like cellulose are largely indigestible so
they pass through
What fatty acid has the carbon skeleton designation of 18:1 (delta 9) - ANS oleic acid
Which coenzyme of the pyruvate dehydrogenase complex is reduced during the transfer of
acetate? - ANS lipoate
Which of the citric acid enzymes are irreversible? - ANS alpha-ketoglutarate dehydrogenase
complex, citrate synthase, and isocitrate dehydrogenase
What enzyme in the citric acid cycle is membrane bound? - ANS succinate dehydrogenase
True or false: The glyoxylate cycle provides a method for fatty acids to be converted to glucose
and exists in plants but not in animals - ANS true
What hormones can result in similar metabolic changes as glucagon? - ANS cortisol and
epinephrine/adrenaline
Indicate the effect of each on the overall rate of the citric acid cycle. Explain.a. increased
[citrate]b. increased [ATP]c. increased [succinyl-CoA] - ANS all decrease rate of citric acid
cyclea. inhibits citrate synthaseb. inhibits citrate synthase and isocitrate dehydrogenasec.
inhibits alpha-ketoglutarate dehydrogenase
T or F: The glyoxylate cycle allows the products of fatty acid oxidation to be converted,
eventually, to glucose - ANS True
T or F: the glyoxylate cycle depletes cellular stores of oxaloacetate - ANS false (makes more to
make glucose through gluconeogenesis)
, T or F: the glyoxylate cycle occurs instead of the citric acid cycle in plants. Explain - ANS false.
the citric acid cycle occurs in plants that can photosynthesize. The glyoxylate cycle is active in
the seeds of the plants prior to germination (produces glucose that photosynthesis would
typically produce)
T or F: individuals with Type I diabetes mellitus are hyperglycemic and hypoinsulinemic - ANS
true. these individuals cannot produce insulin (autoimmune disease that attacks pancreatic beta
cells). Insulin would normally signal for glucose uptake by cells, so without it blood glucose is
high
True or false: Electron transport complexes I, II, III, and IV are all proton pumps - ANS false.
complex II is not
Where do the electrons from NADH and FADH2, respectively, enter the mitochondrial ETC?
What effect does this have on the number of ATPs produced from the redox of each carrier? -
ANS NADH donates electrons to complex I. This results in the pumping of 10 protons, which
can be used to make 2.5 ATP.FADH2 donates electrons to complex II, which cannot act as a
proton pump, so only 6 protons are pumped from FADH2 electrons. Therefore, only 1.5 ATP are
produced.
single electron acceptor located in the inner membrane space of the mitochondria - ANS
cytochrome C
hydrophobic molecule that diffuses in the inner mitochondrial membrane - ANS CoQ
component of all four electron transfer complexes that is bound by cysteine residues - ANS
Fe-S clusters
Explain the role of each conformation of the αβ subunits of ATP synthase in ATP synthesis -
ANS αβ-empty (O): releases ATPαβ-ATP (T): catalyzes ATP synthesis and tightly binds
ATPαβ-ADP (L): binds ADP + Pi (not catalytically active)
Dietary lipids are absorbed across the intestinal wall as ________ and then resynthesized into
________. - ANS free fatty acids; triacylglycerols
Triacylglycerols are packaged, along with other lipids such as cholesterol, and protein into
________. These are transported through the _____ system. - ANS chylomicrons; lymphatic
Once in the blood system, fatty acids are taken up into extra-hepatic cells after being released
by _______. - ANS lipoprotein lipase
hydrolyzes fatty acids from triacylglycerols - ANS lipoprotein lipase and hormone sensitive
lipase
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