plant cell signalling

Question 1

plant anatomical structures that play a role in hormone signal generation and transport

Answer 1

meristems
phloem
xylem
parenchyma cells
endodermis
cortex and epidermis
stomata
these structures work to produce, transport and regulate plant hormones ensuring proper development, growth and adaptation to environmental changes

Question 2

meristems

plant anatomical structures in hormone signal generation and transport

Answer 2

regions of active cell division at the tips of roots and shoots
produce plant hormones like auxins, cytokinins and gibberellins which are critical for growth and differentiation

Question 3

phloem

plant anatomical structures in hormone signal generation and transport

Answer 3

vascular tissue
responsible for transporting hormones throughout the plant

Question 4

xylem

plant anatomical structures in hormone signal generation and transport

Answer 4

primarily responsible for water and mineral transport
carries abscisic acid which plays a key role in stress responses

Question 5

signalling in plants

Answer 5

horomonal signalling
signal transduction pathways
plasmodesmata and cell-to-cell signalling
systemic signalling
environmental signalling

Question 6

major classes of plant hormones

Answer 6

auxins
cytokinins
gibberellins
abscisic acid
ethylene
brassinosteroids
jasmonic acid
salicylic acid
strigolactones

Question 7

F-box proteins in hormone perception

Answer 7

ubiquitin-proteasome system to regulate the degradation of specific proteins
SCF complex
auxin signalling
gibberellin signalling
strigolactone signalling
jasmonic acid signalling

Question 8

SCF complex

F-box proteins in hormone perception

Answer 8

mediates the attachment of ubiquitin to target proteins tagging them for degradation in the proteasome to control the levels of key regulatory proteins involved in hormone responses

Question 9

auxin signalling

F-box proteins in hormone perception

Answer 9

the TIR1/AFB family act as receptors for auxin
binding of auxin triggers interaction of the F-box protein with Aux/IAA proteins which are transcriptional repressors
promotion of ubiquitination and degradation of the Aux/IAA protins to allow the activation of auxin-responsive genes
regulates growth processes - cell elongation and differentiation

Question 10

Gibberellin signalling

F-box proteins in hormone perception

Answer 10

F-box proteins target DELLA protiens for degradation
DELLA proteins are negative regulators of giberellin signalling
allows the activation of genes that promote growth - stem elongation and cell germination

Question 11

strigolactone signalling

F-box proteins in hormone perception

Answer 11

promotion of symbiotic interactions with mycorrhizial fungi
regulate shoot branching, root development and stress responses

Question 12

jasmonic acid signalling

F-box proteins in hormone perception

Answer 12

regulate the degradation of JAZ proteins which act as repressors of Jasmonic acid signalling
allows the activation of genes involved in defense responses and stress adaptation.

Question 13

histidine kinases in hormone perception

Answer 13

function through a two-component signalling system
acts as the sensor and initiates a cascade of intracellular signalling events
- signal perception
- autophosphorylation
- phosphotransfer
- gene expression regulation
* cytokinin perception
* ethylene signalling
* abscisic acid signalling

Question 14

signal perception

histidine kinases in hormone perception

Answer 14

histidine kinase acts as a sensor for the hormone or environmental signal

Question 15

autophosphorylation

histidine kinases in hormone perception

Answer 15

histidine kinase undergoes a confromational change in response to hormone detection to activate its kinase activity
the histidine residue is autophosphorylated.

Question 16

phosphotransfer

histidine kinases in hormone perception

Answer 16

the phosphate is transferred from the histidine kinase to the response regulator which is a transcription factor or intermediate signalling molecule
activates or deactivates the ability of the response regulator to bind DNA or interact with other cellular components

Question 17

gene expression regulation

histidine kinases in hormone perception

Answer 17

the active phosphorylated response regulator moves to the nucleus and regulates the expression of specific genes

Question 18

cytokinin perception

histidine kinases in hormone perception

Answer 18

regulation of cell division and differentiation
histidine kinase receptors detect the cytokinin and initiate the signalling cascade
activated response regulators regulate gene expression involved in growth and differentiation

Question 19

ethylene signalling

histidine kinases in hormone perception

Answer 19

regulation of genes involved in stress response, fruit ripening, and senescence

Question 20

abscisic acid signalling

histidine kinases in hormone perception

Answer 20

critical for plant responses to stress

Question 21

regulation of receptor kinase signalling

Answer 21

ligand binding initiates receptor activation and dimerisation
autophosphorylation of the kinase domain activates downstream signalling
kinases, phosphatases and transcription factors propagate the signal
phosphorylation and dephosphorylation balance modulates signalling intensity
endocytosis and receptor trafficking regulate the duration and intensity of the signal