BIOCHEM C785 Biochemistry Module 4 with complete solution

Biochemistry Module 4

The polysaccharide cellulose is composed of sugar monomers linked through ______ linkages, with their CH2OH groups in _________ direction relative to the neighboring monomer.

Select one:

a. Beta; opposite Correct! Polysaccharides of nondigestible Carbohydrates (the "fiber" in our diets) are held together by bonds known as beta linkages between individual monosaccharides; their CH2OH groups are orientated in an opposite direction relative to its neighbors. These bonds make cellulose indigestible in our bodies. b. gamma; same

c.  alpha; opposite

d.  beta; same

Which of the following nutrients cannot be broken down to a substance that can participate in the production of ATP via aerobic cellular metabolism?

Select one:

a.       Correct! Vitamins are not nutrients that can be broken down in the process of creating ATP; rather they are essential in small quantities to serve as coenzymes or cofactors in enzymatic processes. Vitamin E is an antioxidant

b.      Lipids

c.       Protein

d.      Complex Carbohydrates

Glycolysis produces two ATP molecules. Through what process are these ATP molecules made?

Select one:

a. Substrate level phosphorylation Correct! The reactions within glycolysis directly form a bond between ADP and Pi to form ATP in the process of substrate level phosphorylation b. Oxidative phosphorylation

c.  Electron transport chain

d.  Beta oxidation

What product of beta oxidation is able to enter the citric acid cycle?

Select one:

a. Acetyl CoA Correct! Acetyl CoA made by the process of beta oxidation enters the citric acid cycle b. Glucose

c.  Glycerol

d.  Fatty acyl-CoA

What process is shared between anaerobic and aerobic Metabolism ? Select one:

a. Glycolysis Correct! The pyruvate produced in glycolysis will have different fates based on the availability of oxygen, but glycolysis will occur regardless of oxygen's presence or absence. b. Lactate fermentation

c.  Electron transport chain

d.  Citric acid cycle

A defect occurs that prevents pyruvate from converting to lactate under anaerobic conditions. What is a possible consequence?

Select one:

a.  Glycolysis continues because NAD+ levels are low

b.  Glycolysis continues because NAD+ levels are high

c.  Glycolysis stops because NAD+ levels are low

d.  Glycolysis stops because NAD+ levels are high Incorrect. When pyruvate is converted into lactate, NADH is oxidized to NAD+. If this conversion does not happen, NAD+ is not generated. Without NAD+, glycolysis could not continue.

Which of the following differentiates aerobic from anaerobic cellular Metabolism ?

Select one:

a.  The breakdown of glucose into compound with fewer carbon atoms

b. The utilization of O2 as an electron acceptor Correct! Only in aerobic respiration is O2 consumed and this occurs in the last step of the electron transport chain. Oxygen acts as the final electron acceptor and forms water during this step c. The production of ATP

d. The use of ingested food to create energy

Which of the following processes does NOT take place in the mitochondria of a cell? Select one:

a.  Production of FADH2

b. Conversion of pyruvate to lactic acid Correct! When oxygen is scarce, pyruvate--created through glycolysis---remains in the cytosol and will be converted anaerobically into lactate (fermentation) c. Creation of a proton gradient

d. Production of CO2 in the citric acid cycle

Under anaerobic conditions in humans, which molecule is formed in the cytosol by fermentation? Select one:

a.  Glucose-6-phosphate

b.  Acetyl-CoA

c.  Lactate Correct! When there is no oxygen available for cellular respiration, for example, during strenuous muscular exercise, the pyruvate formed via glycolysis will be fermented into lactic. The lactate will be sent to the liver for conversion back into glucose via the Cori cycle

d.  Fructose