Cell Signalling and Transduction
A signal cascade induced by adrenaline or thyroxine

results in the activation of a sequence of enzymes needed for the cell effect
All of these
involves the activation of a G protein
must begin with receipt of the signal molecule by a surface receptor

ANSWER DOWNLOAD EXAMIANS APP

Cell Signalling and Transduction
The signaling molecules called steroid hormones

are hydrophilic and so cannot penetrate the plasma membrane
bind to cell surface receptors to trigger chemical cascades
never enter the blood of humans
are made in one location of the body but have their effects some distance away

ANSWER DOWNLOAD EXAMIANS APP

Cell Signalling and Transduction
The binding of ligands to many G-proteins linked receptors leads to shortlived

increase in the concentration of certain extracellular signaling molecules called first messenger
decrease in the concentration of certain extracellular signaling molecules called first messenger
increase in the concentration of certain intracellular signaling molecules called second messenger
decrease in the concentration of certain intracellular signaling molecules called second messenger

ANSWER DOWNLOAD EXAMIANS APP