Stress response Flashcards
What is oxidative stress?
Oxidative stress occurs when a cell produces too much oxygen leading to self reaction
What macromolecules will oxygen react with?
DNA, RNA, Lipids, Proteins
What type of oxidative stress does O2- generate?
Superoxide stress
What type of oxidative stress does H2O2 generate?
Peroxide stress
What genes positively regulate the proteins involved in superoxide stress?
SoxR and SoxS
What is the name of the enzyme which the cell produces in order to grant superoxide stress?
Superoxide dismutase
Is superoxide toxic?
Superoxide itself isn’t toxic, However it’s byproduct (Oh radicals) are
What does an elevated superoxide concentration lead to?
Increased intracellular free iron (called the fenton reaction)
What happens if you lose FUR
Enter oxidative stress
What is the name of the regulator of the genes involved in peroxide stress?
OxyR
What is the frontline defence against peroxide stress?
Glutathionine
What is the mechanism of action of Glutathionine for peroxide stress
Act as a hydrogen donor to restore oxidised macromolcules
How does the cell maintain a pool of reduced glutathione?
Gkutathione oxidoreductase is produced to keep the glutathionine negatively charged
What is the purpose of catalase in peroxide stress?
Converts hydrogen peroxide into water and oxygen
What is hypoosmotic stress?
When there is a higher solute concentration inside the cell leading to water flooding the cell
How does the bacteria prevent hypoosmotic stress?
Mechanosensitive channels will become activates in a gradient response, slowly opening more and more channels
What is hyperosmotic stress?
When there is a higher solute concentration outside the cell leading to water flooding the cell
How does the bacteria prevent hyperosmotic stress?
Increasing the concentration of compatible solutes which reduces water activity of the cell
What are the general characteristics of the compatible solutes?
Unable to cross membrane
Do not carry net electrical charge
