Communication and Signalling Flashcards
state three example of extracellular signalling molecules:
steroid hormones, peptide hormones and neurotransmitters
hydrophobic signalling molecules:
diffuse directly through the phospholipid bilayer and so bind to intracellular receptors either in the cytosol or the nucleus
what is the name of hydrophobic signalling molecule receptors?
transcription factors
what is the role of transcription factors?
proteins that when bound to DNA can either stimulate or inhibit the transcription of DNA
three examples of hydrophobic signalling molecules:
steroid hormones
oestrogen
testosterone
what happens if a hormone binds to a receptor in the cytosol?
the hormone receptor complex would move to the nucleus and bind to specific sites on DNA and affect gene expression
what is the name of the specific bing sites on DNA?
hormone response elements
how do hydrophilic signalling molecules operate?
they bind to transmembrane receptors as ligands and do not enter the cytosol
two examples of hydrophilic signalling molecules:
peptide hormones and neurotransmitters
what occurs following the binding of a hydrophilic signalling molecule?
transmembrane receptors change conformation and act as signal transducers. The signal is transduced across the plasma membrane and the ligand binding event is converted into intracellular signals which alter the behaviour of the cell
what is meant by the resting membrane potential of a neuron?
a state in which there is no nervous impulse being transmitted
what is a neurotransmitter receptor?
ligand-gated ion channels with a synaptic region at one end of the neuron.
summarise neurotransmission:
binding cause the channels to open and sodium ions enter the cell. The changes in potential caused by entry of sodium ions opens voltage gated channels allowing more sodium ions to flow in and maybe reaching the threshold. changes in potential now close sodium channels and open potassium channels-causing repolarisation. the sodium-potassium pump restores the resting potential.
