Chapter 12 BIOLOGIC OXIDATION

Question 1

defined as the removal of electrons

Answer 1

Oxidation

Question 2

gain of electrons

Answer 2

Reduction

Question 3

the process by which cells derive energy in the form of ATP from the controlled reaction of hydrogen with oxygen to form water

Answer 3

Respiration

Question 4

molecular oxygen is incorporated into a variety of substrates by enzymes designated as

Answer 4

Oxygenases

Question 5

many drugs, pollutants, and chemical carcinogens (xenobiotics) are metabolized by enzymes of this class, known as the

Answer 5

cytochrome P450 system

Question 6

Enzymes involved in oxidation and reduction are called

Answer 6

Oxidoreductases

Question 7

Oxidoreductases are classified into four groups namely

Answer 7

1. Oxidases
2. Dehydrogenases
3. Hydroperoxidases
4. Oxygenases

Question 8

• is a hemoprotein widely distributed in many tissues, having the typical heme prosthetic group present in myoglobin, hemoglobin, and other cytochromes
• is the terminal component of the chain of respiratory carriers found in mitochondria

Answer 8

Cytochrome oxidase

Question 9

• The action of the this enzyme is blocked by carbon monoxide, cyanide, and hydrogen sulfide, and this causes poisoning by preventing cellular respiration.
• It has also been termed “cytochrome a3.”

Answer 9

Cytochrome oxidase

Question 10

The heme a3is combined with another heme, heme a, in a single protein to form the cytochrome oxidase enzyme complex, and so it is more correctly termed ___

Answer 10

cytochrome aa3

Question 11

Flavoprotein enzymes contain ___ as prosthetic groups.

Answer 11

flavin mononucleotide (FMN) or flavin adenine dinucleotide (FAD)

Question 12

an enzyme found in kidney with general specificity for the oxidative deamination of the naturally occurring l-amino acids

Answer 12

l-amino acid oxidase

Question 13

which contains molybdenum and plays an important role in the conversion of purine bases to uric acid

Answer 13

xanthine oxidase,

Question 14

FAD-linked enzyme present in mammalian livers, which contains molybdenum and nonheme iron and acts upon aldehydes and N-heterocyclic substrates

Answer 14

aldehydedehydrogenase

Question 15

There are a large number of enzymes in the dehydrogenase class. They perform the following two main functions:

Answer 15

1. Transfer of hydrogen from one substrate to another in
   a coupled oxidation–reduction reaction
2. Transfer of electrons in the respiratory chain of electron
   transport from substrate to oxygen

Question 16

Crossroads of metabolism, the link between anabolic and catabolic pathways

Answer 16

Amphibolic

Question 17

– Measure of heat content of the reactants and products

– Measured in joules (J)

Answer 17

Enthalpy (ΔH)

Question 18

True or False

Flavin groups are not generally more tightly bound to their apoenzymes than are the nicotinamide coenzymes.

Answer 18

False

Question 19

acts as a carrier of electrons between NADH and the components of higher redox potential

Answer 19

NADH dehydrogenase

Question 20

is an intermediary carrier of electrons between acyl-CoA dehydrogenase and the respiratory chain

Answer 20

electron-transferring flavoprotein (ETF)

Question 21

are iron-containing hemoproteins in which the iron atom oscillates between Fe3+ and Fe2+ during oxidation and reduction

Answer 21

cytochromes

Question 22

Two type of enzymes found both in animals and plants fall

into the hydroperoxidase category:

Answer 22

1. peroxidases

2. catalase

Question 23

play an important role in protecting the body against the harmful effects of reactive oxygen species (ROS)

Answer 23

Hydroperoxidases

Question 24

are highly reactive oxygen-containing molecules such as peroxides which are formed during normal metabolism, but can be damaging if they accumulate

Answer 24

reactive oxygen species (ROS)

Question 25

are found in milk and in leukocytes, platelets, and other tissues involved in eicosanoid metabolism

Answer 25

Peroxidases

Question 26

Prosthetic group of peroxidase

Answer 26

protoheme

Question 27

catalyzes the destruction of H2O2 and lipid hydroperoxides through the conversion of reduced glutathione to its oxidized form, protecting membrane lipids and hemoglobin against oxidation by peroxides

Answer 27

glutathione peroxidase

Question 28

• is a hemoprotein containing four heme groups. It
  can act as a peroxidase, catalyzing reactions of the type
  -is also able to catalyze the breakdown of H2O2 formed by the action of oxygenases to water and oxygen

Answer 28

Catalase

Question 29

catalyze the incorporation of oxygen into a substrate molecule in two steps:
(1) oxygen
is bound to the enzyme at the active site
(2) the bound oxygen is reduced or transferred to the substrate

Answer 29

Oxygenases

Question 30

2 Subgroups of Oxygenates

Answer 30

1. dioxygenases

2. monooxygenases

Question 31

are an important superfamily of hemecontaining monooxygenases, and >50 such enzymes have been found in the human genome

Answer 31

Cytochromes P450

Question 32

Transfer of a single electron to O2 generates the potentially damaging ____, which gives rise to free-radical chain reactions, amplifying its destructive effects

Answer 32

superoxide anion free radical