Stress Flashcards
name 5 things that can put/cause stress on an organism
Temperature, pH, pro-oxidants, metals, osmolytes
what two things influence and organisms stress threshold
genetics and physiological factors
what allowed the identification of stress response genes
transcriptomics
what allows many organisms to cope with heat
heat shock proteins
can be modified GM to make them more resistant
what is the ‘adaptive response’ to stress and what causes it
exposure to non-lethal dose of stress - protects you against higher doses of stress next time
caused by the up-regulation of genes that help them cope
what is cross-tolerance and what does this suggest
when an organism adapted to one type of stress shows elevated resistance to other stresses
tells us there are general stress pathways
how is stress sensed to trigger a response
plasma-membrane bound protein interacts with the chemical, triggering a signalling cascade where a MAP-kinase is phosphorylated, then in turn phosphorylates something else etc…
what is the two- component regulatory system in bacteria
the chemical can activate a sensor protein which phosphorylates something
or can activate a response regulator - which regulates transcription
why is there phosphate present in the cells/ membrane
to return response regulator to its non-phosphorylated state - no longer blocks transcription
why does bacteria activate desaturase enzymes when faced with cold stress
as this introduces double bonds - kinks- in the fatty acid chains -increasing membrane fluidity counteracting the cold
what is a cryoprotectant
a substance that prevents the freezing of tissues, or prevents damage to cells due to freezing
eg. trehalose
why might microos have good stress responses to temperature
as they can’t regulate their own temperature - very dependent on the environment
what does heat stress cause
nucleic acid degradation - increased mutation, degradation of H bonds, protein denaturation, membrane fluidity
the synthesis of what helps stabilise macro molecules as a response to heat stress
trehalose
what are the two response molecules to cope with heat stress in yeast
HSE - heat shock element - bind to heat shock factor
STRE - stress response element
