Stress response

Question 1

What is oxidative stress?

Answer 1

Oxidative stress occurs when a cell produces too much oxygen leading to self reaction

Question 2

What macromolecules will oxygen react with?

Answer 2

DNA, RNA, Lipids, Proteins

Question 3

What type of oxidative stress does O2- generate?

Answer 3

Superoxide stress

Question 4

What type of oxidative stress does H2O2 generate?

Answer 4

Peroxide stress

Question 5

What genes positively regulate the proteins involved in superoxide stress?

Answer 5

SoxR and SoxS

Question 6

What is the name of the enzyme which the cell produces in order to grant superoxide stress?

Answer 6

Superoxide dismutase

Question 7

Is superoxide toxic?

Answer 7

Superoxide itself isn’t toxic, However it’s byproduct (Oh radicals) are

Question 8

What does an elevated superoxide concentration lead to?

Answer 8

Increased intracellular free iron (called the fenton reaction)

Question 9

What happens if you lose FUR

Answer 9

Enter oxidative stress

Question 10

What is the name of the regulator of the genes involved in peroxide stress?

Answer 10

OxyR

Question 11

What is the frontline defence against peroxide stress?

Answer 11

Glutathionine

Question 12

What is the mechanism of action of Glutathionine for peroxide stress

Answer 12

Act as a hydrogen donor to restore oxidised macromolcules

Question 13

How does the cell maintain a pool of reduced glutathione?

Answer 13

Gkutathione oxidoreductase is produced to keep the glutathionine negatively charged

Question 14

What is the purpose of catalase in peroxide stress?

Answer 14

Converts hydrogen peroxide into water and oxygen

Question 15

What is hypoosmotic stress?

Answer 15

When there is a higher solute concentration inside the cell leading to water flooding the cell

Question 16

How does the bacteria prevent hypoosmotic stress?

Answer 16

Mechanosensitive channels will become activates in a gradient response, slowly opening more and more channels

Question 17

What is hyperosmotic stress?

Answer 17

When there is a higher solute concentration outside the cell leading to water flooding the cell

Question 18

How does the bacteria prevent hyperosmotic stress?

Answer 18

Increasing the concentration of compatible solutes which reduces water activity of the cell

Question 19

What are the general characteristics of the compatible solutes?

Answer 19

Unable to cross membrane
Do not carry net electrical charge