stiner- oxygen

Question 1

oxygen

Answer 1

highly combustable at high temps

but inert at body temps

Question 2

90% of oxygen is committed to what

Answer 2

oxadative phosphoylation

Question 3

at body temp activation of O2 is by what

Answer 3

metal ions, iron, copper, manganese

Question 4

what are ROS

Answer 4

reactive oxygen species

partially reduced. reactive forms of oxygen.

Question 5

what is the end product of complete oxygen reduction

Answer 5

water

Question 6

oxidative stress occurs when?

Answer 6

when rate of ROS generation exceeds the rate of neutralizing them

Question 7

ROS can be used by what for what reasons

Answer 7

by immune cells to destroy pathogens

Question 8

excess ROS leads to what

Answer 8

increase in oxidative damage to biomolecules

Question 9

most prevalent ROS in blood and tissue is what

Answer 9

H2O2, hydrogen peroxide

Question 10

what is the most reactive and damaging radical

Answer 10

OH

Question 11

what is a radical

Answer 11

cluster of atoms, one of which contains an unpaired electron in its outermost shell
highly reactive
highly unstable

Question 12

3 ways ROS are formed

Answer 12

1. By reaction of oxygen with de-compartmentalized metal ions
2. As a side reaction of mitochondrial electron transport
3. Normal enzymatic reactions- formation of H202 by fatty acid oxidases in the peroxisome

Question 13

another source of ROS

Answer 13

activation of polymorphonuclear leukocytes (PMN) during inflammatory conditions
-example is myeloperoxidase

Question 14

what does myeloperoxidase do?

Answer 14

convert H2O2 and Cl- to hypochlorous acid (HOCl)

Question 15

one of the most sensitive places for ROS damage? and why?

Answer 15

cell membrane. rich is polyunsaturated fatty acids which easily react with ROS

Question 16

why does damage occur?

Answer 16

The hydroxyl radical is known to react with all components of the DNA molecule, damaging both the purine and pyrimidine bases and also the deoxyribose backbone

Question 17

Permanent modification of genetic material resulting from these “oxidative damage” incidents represents the first step involved in what?

Answer 17

in mutagenesis, carcinogenesis, and ageing.

Question 18

The most extensively studied DNA lesion is the formation of 8-OH-G

Answer 18

8-OH-G

Question 19

what else is very susceptible to ROS damage

Answer 19

side chains of amino acids, particularly cystine and methionine

Question 20

what increases the intracellular production of ROS

Answer 20

AGEs and their attachment to RAGE receptors on cell membranes

Question 21

what are positive uses of ROS?

Answer 21

1. The cells of the thyroid gland must make hydrogen peroxide in order to attach iodine atoms to thyroglobulin in the synthesis of thyroxine
2. Macrophages and neutrophils must generate ROS in order to kill some types of bacteria that they engulf by phagocytosis

Question 22

antioxidate defense against ROS

Answer 22

1. superoxide dimutase
2. small molecules that are antioxidants
   vitamin A, C, E, uric acid

Question 23

what does superoxide dimutase do?

Answer 23

which converts two superoxide anions into a molecule of hydrogen peroxide and one of oxygen, and catalase (converts hydrogen peroxide to water and oxygen)