exam 3

1. When electrons are lost during a metabolic oxidation: (2 points)

   • They go off into the environment.

   • They are neutralized by protons.

   •  They are picked up by a coenzyme.

   • Carbon dioxide is always given off.

They are picked up by a coenzyme

1. Which of the following represents the correct pair of oxidized/reduced coenzymes?

   1. NAD*/NADH

   2. FAD/FADH

   3. NAD* /NADH2

   4. NAD*/FADH2

NAD*/NADH

1. In steps 5-8 of the citric acid cycle, the high-energy molecules------, --------and ----- are produced, and-------is regenerated to begin another turn of the cycle. (2 points)

   1. GDP; FADH2; NADH/H*; oxaloacetate

   2. GTP; FADH2; NADH/H+; oxaloacetate

   3. GTP; FADH2; NADH/H+; citrate

   4. GDP; FAD; NAD+; oxaloacetate

   5. GDP; FADH2; NADH/H+; isocitrate

GTP; FADH2; NADH/H+; oxaloacetate

1. The mitochondria are the location where----- takes place and most----- is produced. (2 points)

   1. citric acid cycle; ATP

   2. digestion; acetyl coenzyme A

   3. digestion, ATP

   4. citric acid cycle; acetyl coenzyme A

   5. digestion; fatty acid

citric acid cycle; ATP

1. The common molecule produced from all foods at the second stage of catabolism is

   1. ADP.

   2. acetyl-SCoA.

   3. Glucose.

   4. citric acid.

   5. carbon dioxide.

acetyl-SCoA

1. Which of the following is not true of the citric acid cycle?

   1. All enzymes of the cycle are located in the cytoplasm, except succinate dehydrogenase, which is bound to the inner mitochondrial membrane.

   2.  In the presence of malonate, one would expect succinate to accumulate.

   3. Oxaloacetate is used as a substrate but is not consumed in the cycle.

   4. Succinate dehydrogenase channels electrons directly into the electron transfer chain.

   5. The condensing enzyme is subject to allosteric regulation by ATP and NADH.

All enzymes of the cycle are located in the cytoplasm, except succinate dehydrogenase, which is bound to the inner mitochondrial membrane.

1. The oxidative decarboxylation of alpha-ketoglutarate proceeds by means of multistep reactions in which all but one of the following cofactors are required Which one is not required?

   1. ATP

   2. Coenzyme A

   3. Lipoic acid

   4. NAD+

   5. Thiamine pyrophosphate

ATP

1. Almost all of the oxygen (O2) one consumes in breathing is converted to:

   1. acetyl-CoA.

   2. carbon dioxide (CO2).

   3. carbon monoxide, and then to carbon dioxide.

   4. None of the above

   5. water.

water

1. The relative concentrations of ATP and ADP control the cellular rates of.

   1. Glycolysis.

   2. oxidative phosphorylation.

   3. pyruvate oxidation

   4. the citric acid cycle.

   5. All of the above

All of the above

1. Citrate synthase and the NAD+-specific isocitrate dehydrogenase are two key regulatory enzymes of the citric acid cycle. These enzymes are inhibited by:

   1. acetyl-CoA and fructose 6-phosphate.

   2. AMP and/or NAD†

   3. AMP and/or NADH.

   4. ATP and/or NAD*.

   5. ATP and/or NADH

ATP and/or NADH

1. The two main purposes of the citric acid cycle are? 

   1. Synthesis of citrate and gluconeogenesis

   2. Degradation of acetyl-COA to produce energy and to produce energy and to supply precursors for anabolism

   3. Degradation of pyruvate to produce energy and to supply precursors for anabolism

   4. Degradation of glucose to produce energy and to supply precursors for anabolism

   5. Degradation of pyruvate to produce energy and to synthesize oxaloacetate to gluconeogenesis

Degradation of acetyl-COA to produce energy and to produce energy and to supply precursors for anabolism

1. Which of the following answers completes the sentence correctly? Succinate dehydrogenase----

   1. is an iron-sulfur protein like aconitase.

   2. contains FAD and NAD+ cofactors like pyruvate dehydrogenase.

   3. is an integral membrane protein, unlike other enzymes of the citric acid cycle.

   4. carries out an oxidative decarboxylation like isocitrate dehydrogenase.

   5. is inhibited by mevalonate.

is an integral membrane protein, unlike other enzymes of the citric acid cycle.

1. A reaction which involves substrate-level phosphorylation is:

   1. isocitrate-----> a-ketoglutarate

   2. citrate----> isocitrate

   3. succinyl COA----> succinate

   4. succinate---->fumarate

   5. Fumarate----malate

succinyl COA----> succinate

1. Conversion of 1 mol of acetyl-CoA to 2 mol of CO2 and CoA via the citric acid cycle leads to the net production of:

   1. 1 mol of citrate

   2. 1 mol of FADH2

   3. 1 mol of NADH

   4. 1 mol of oxaloacetate

   5. 7 mol of ATP

1 mol of FADH2

1. A water-soluble component of the electron transport chain that can diffuse freely in the intermembrane space and can carry electrons is -------

   1. Ubiquinone

   2. 2,3-BPG

   3. Cytochrome c

   4. Cytochrome oxidase

   5. Heme

Cytochrome c

1. Which of the following statements about the chemiosmotic theory is correct?

   1. Electron transfer in the mitochondria is accompanied by an asymmetric accumulation of protons on one side of the inner mitochondrial membrane.

   2. It predicts that oxidative phosphorylation can occur even in the absence of an intact inner mitochondrial membrane.

   3. The effect of uncoupling reagents is a consequence of their ability to carry electrons through membranes.

   4. The membrane ATP synthase has no significant role in the chemiosmotic theory.

   5. All of the above are correct.

Electron transfer in the mitochondria is accompanied by an asymmetric accumulation of protons on one side of the inner mitochondrial membrane.

1. How many fused rings are present in steroid molecules?

   1. 0

   2. 2

   3. 3

   4. 4

   5. 5

4

1. Compared to that of a saturated fatty acid, the melting point of an unsaturated fatty acid with an equal number of carbons will be (2 points)

   1.  the same.

   2. Lower.

   3. Higher.

   4. More information is needed.

Lower

1. Cholesterol is transported in the blood in the form of: (2 points)

   1. free cholesterol

   2. Oligosaccharide

   3. LDL

   4. leukotrienes

   5. None of the above

LDL

1. Which of the following is not a characteristic of fatty acids? (2 points)

   1. even number of carbons

   2. double bonds

   3. 10-20 carbons

   4. branched

   5. synthesized by the human body

branched

1. Saturated triacylglycerols are usually------because-----

   1.  liquids; they have relatively short fatty acid chains

   2. liquids; their rigid fatty acid chains do not fit together closely

   3. liquids; they contain impurities from their natural sources

   4. solids; they have relatively long fatty acid chains

   5. solids; their flexible fatty acid chains allow the molecules to fit together closely

solids; their flexible fatty acid chains allow the molecules to fit together closely

1. Which reaction can be used to convert oils into fats?

   1. Hydrogenation

   2. Hydrolysis

   3. Esterification

   4. Saponification

   5. dehydration

Hydrogenation

1. The saponification reaction used to form soaps can be more specifically described as

   1. acid hydrolysis.

   2. basic hydrolysis.

   3. Hydrogenation.

   4. Dehydrogenation.

   5. dehydration.

basic hydrolysis

1. The compound that is the immediate precursor to the prostaglandins is

   1. Cholesterol.

   2. oleic acid.

   3. stearic acid.

   4. arachidonic acid.

   5. leukotriene.

arachidonic acid

1. The hydrocarbon end of a soap molecule is

   1. hydrophilic and attracted to grease.

   2. hydrophobic and attracted to grease.

   3. hydrophilic and attracted to water.

   4. hydrophobic and attracted to water.

   5. neither hydrophobic nor hydrophilic

hydrophobic and attracted to grease

1. The process of transport across cell membranes which costs biochemical energy is

   1. simple diffusion.

   2. facilitated diffusion.

   3. active transport.

   4. Osmosis.

   5. none of the above

active transport

1. The biochemical roles of lipids are

   1. short-term energy storage, transport of molecules, and structural support.

   2. storage of excess energy, components of cell membranes, and chemical messengers.

   3. catalysis, protection against outside invaders, and motion.

   4. component of cell membranes, catalysis, and structural support.

   5. neurotransmitters, hormones, transport of molecules.

storage of excess energy, components of cell membranes, and chemical messengers

1. Biomolecules can be classified as lipids on the basis of

   1. a common structure consisting of long hydrocarbon chains.

   2. the presence of many hydroxyl groups and at least one carbonyl group.

   3. the presence of at least one amine group and one carboxylic acid group on each molecule.

   4. the physical properties of odor, color, and melting point within certain guidelines.

   5. the physical property of solubility in nonpolar organic solvents.

the physical property of solubility in nonpolar organic solvents

1. Which of the following is not a consequence of partial hydrogenation of vegetable oils?

   1. Longer shelf life

   2. Lower melting temperature

   3. Reduction of some cis double bonds to single bonds

   4. Conversion of some cis double bonds to trans double bonds

   5. Increased risk of cardiovascular disease upon consumption by humans

lower melting temperature

1. Which of the following is not a fat-soluble vitamin?

   1. A

   2. C

   3. D

   4. E

   5. K

C

1. Triacylglycerols obtained from the diet are transported through the lymph system and bloodstream by which of the following lipoproteins?

   1. LDL

   2. HDL

   3. VLDL

   4. Chylomicrons

Chylomicrons

1. Triacylglycerols are synthesized from glycerol and:

   1. Fatty acids

   2. Cholesterol

   3. Sphingosine

   4. Acetyl-CoA

Fatty acids

1. Which of the following statements apply (applies) to the B-oxidation of fatty acids?

   1. The process takes place in the cytosol of mammalian cells.

   2. Carbon atoms are removed from the acyl chain one at a time.

   3. Before oxidation, fatty acids must be converted to their CoA derivatives.

   4. NADP+ is the electron acceptor.

   5. The products of B oxidation can directly enter the citric acid cycle for further oxidation.

a.     1 and 3 only.

b.     1, 2, and 3

c.     1, 2, and 5

d.     3 and 5 only.

e.     4 only

3 and 5 only

34. The complete metabolism of one molecule of myrisic acid, a fatty acid with 14 atoms of carbon, would require-----turns of the beta-oxidation cycle.

    1.  6

    2.  7

    3. 12

    4. 14

    5. 16

6

34. Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires.

    1. ATP, carnitine, and coenzyme A.

    2. ATP, carmitine, and pyruvate dehydrogenase.

    3. ATP, coenzyme A, and hexokinase

    4. ATP, coenzyme A, and pyruvate dchydrogenase.

    5. carmitine, coenzyme A, and hexokinase

ATP, carnitine, and coenzyme A

34. The major site of formation of acetoacetate from fatty acids is the:

    1. adipose tissue

    2. Liver.

    3. Brain.

    4. Kidney.

    5. muscle.

Liver