cell signalling in plants Flashcards
(22 cards)
what are factors that plants sense and respond to?
- light
- time (day length and seasons)
- gravity
- wounding by herbivores
- infection by pathogens
- drought/flooding
- touch (wind, objects)
- internal chemical signs
- heat or cold stress
what is de-etiolation?
plants growing in the absence of light
what is signal transduction?
process that cells use to transfer information from sensor molecules such as cell surface receptors to parts of the cell that generate responses
what are the three phases of signal transduction?
- reception
- transduction
- response
how does a light signal cause signal transduction?
slide 9
- light signal is detected by phytochrome receptor -> activates at least 2 signal transduction pathways
- one pathway uses cGMP as second messenger that activates kinase
- another increases cytosolic level of Ca+ to activate other type of protein kinase
how are hormones transported?
- through xylem/phloem
- across cellular membrane
- through tegulated transport proteins
what are 2 common methods of hormonal sognal transduction?
reversiple protein transduction and targeted proteolysis
what are downstream effects of hormonal signal transduction?
changes in gene transcription
changes in other cellular activities like ion transport
which hormones promote cell elongation?
auxin + gibberelin
which hormones help in cell divisoin + growth
auxin, gibberelin, cytokinin
what hormone promotes seed germination?
gibberelin
what hormone aids in fruit ripening?
ethylene
what hormone maintains seed dormancy?
abscisic acid
what hormone promotes abscission?
abscisic acid
how did boysen-jensen prove that the chemical causing bending in a plant with lateral light is water-soluble?
it did not respond to lateraal light when blocked by a solid or butter
what are functions of auxin?
- to stimulate elongation of cells within young developing shoots
- rapidly alters gene expression
- stimulates sustained growth responses
- increases activity of proton pumps, to reduce pH of cell walls…
what are practical uses for auxins?
- vegetative propagation of plants by cuttings
- herbicides
- assisting fruit development
what are functions of cytokinins?
- cell division an differentiation
- apical dominance
- anti-aging: maintaining leaf tissues
what does the release of soluble sugars and starch cause
increased turgor pressure -> loosening of cell wall -> increased cell size
what are functions of gibberellins?
- stem elongation
- fruit growth
- germination
what are functions of abscisic acid (ABA)?
- often antagonises actions of growth hormones
- seed dormancy
-> phosphorylation of ABA
-> seeds germinated when ABA is deactivated - drought tolerance
-> ABA closes stomata
what is the function of ethylene?
- triple response to mechanical stress
-> slowing of stem elongation, stem thickening, horizontal stem growth - leaf abscission
-> allows enzymes to digest cellulose - fruit ripening
