Lecture 3 - Bioenergetics and Biological Oxidations

Question 1

The conversion of glucose to pyruvate (glycolysis) results in the net synthesis of:

Answer 1

2 ATP

2 NADH

Question 2

The oxidation of acetyl-CoA to CO2 (the TCA cycle) results in the synthesis of:

Answer 2

1 GTP
3 NADH
1 FADH2

Question 3

Oxidation of fatty acids does not directly produce high energy phosphate bonds, but for each cycle of oxidation, what is produced?

Answer 3

1 NADH

1 FADH2

Question 4

The oxidation of NADH and FADH2 by the electron transport chain results in the synthesis of:

Answer 4

3 (2.5) or 2 (1.5) ATP

Question 5

The 3 major reactions for interconversions of Adenine Nucleotides (ATP, ADP, AMP) are:

Answer 5

1. Kinase-catalyzed reactions
2. Myokinase (adenylate kinase) reactions
3. Nucleoside diphosphate kinase reactions

Question 6

Myokinase (adenylate kinase) is present in high concentrations in _____.

Answer 6

muscle - it is associated with the myofibril

Question 7

May regulatory enzymes in metabolic pathways are allosterically regulated by:

Answer 7

the adenylate nucleotides

Question 8

The three types of enzymes that catalyze oxidation and reduction reactions are:

Answer 8

1. Dehydrogenases
2. Oxidases
3. Oxygenases

Question 9

Which is NOT a principal difference between NAD+ and NADP+?

A. NADP+ has an additional phosphate group on the ribose moiety
B. NAD+ participates primarily in catabolic pathways which tend to be oxidative in nature
C. NADPH participates mainly in biosynthetic anabolic pathways which are usually reductive in nature
D. NADP/NADPH is found in the cytosol and cannot cross the inner mitochondrial membrane
E. All of the following are principal differences

Answer 9

E

Question 10

Pellegra, characterized by dermatitis, diarrhea, and dementia, is a deficiency of what cofactor?

Answer 10

Niacin (vitamin B3)

Question 11

Nicotinamide Coenzymes are synthesized from _______ and ______.

Answer 11

Niacin and Tryptophan

Question 12

Flavin coenzymes are derived from _______.

Answer 12

Riboflavin

Question 13

Which type of reaction is catalyzed by dehydrogenases requiring nicotinamide coenzymes?

A. Alcohol –> Aldehyde
B. Aldehyde –> Alcohol
C. Keto –> Alcohol
D. Carbon-carbon double bond formation

Answer 13

A - dehydrogenases requiring nicotinamide coenzymes also catalyze Alcohol –> Keto reactions

Question 14

What part of FAD is involved in the transfer of electrons?

Answer 14

A ring system containing nitrogen atoms (isoalloxazine ring)

Question 15

Which type of reaction is catalyzed by dehydrogenases requiring flavin coenzymes?

A. Alcohol –> Aldehyde
B. Aldehyde –> Alcohol
C. Keto –> Alcohol
D. Carbon-carbon double bond formation

Answer 15

D

Question 16

______ catalyze the transfer of electrons from some organic substrate to molecular oxygen via an intermediate carrier.

Answer 16

oxidases

Question 17

________ catalyze hydroxylation of some organic substrate.

Answer 17

monooxygenases

Question 18

Enzymes involved in the hydroxylation of proline and lysine residues of collagen are examples of what class of enzymes?

Answer 18

dioxygenases

Question 19

How are monooxygenases different from dioxygenases?

Answer 19

They incorporate only one of the oxygen atoms into a substrate (the other oxygen gets reduced to H2O).

Question 20

The monooxygenases require a source of reducing power to reduce molecular oxygen to a hydroxyl group and water. The reducing power is supplied by ________.

Answer 20

NADPH

Question 21

What are the 3 proteins that constitute the miniature electron transport chain embedded in the microsomal (SER) membrane?

Answer 21

1. Flavoprotein
2. Non-heme iron protein
3. Cytochrome P450

Question 22

Where are monooxygenases usually located? (2 locations)

Answer 22

1. Mitochondria (steroid hydroxylation reactions)

2. Microsomes (hydroxylation reactions)

Question 23

The 3 major ROS are:

Answer 23

1. Superoxide (O2-)
2. Hydrogen peroxide (H2O2)
3. Hydroxyl radical

Question 24

What enzyme generates H2O2 in the process of detoxifying the superoxide radical?

Answer 24

SOD (Superoxide dismutase)

Question 25

What enzymes reduce hydrogen peroxide to H2O?

Answer 25

Peroxidases

Question 26

What enzymes catalyze the dismutation of hydrogen peroxide to H2O?

Answer 26

Catalase

Question 27

There are two sources of hydrogen peroxide. One is formation by SOD in the process of detoxifying the superoxide radical. The other is via:

Answer 27

Oxidase-Catalyzed Reactions (includes peroxisomal reactions catalyzed by FAD-dependent oxidases, such as amino acid oxidases and the first reaction in the oxidation of fatty acids)

Question 28

Most of the hydrogen peroxide is produced, and the excess destroyed in the __________.

Answer 28

peroxisomes