1.4(c) - Hydrophilic signals Flashcards
What do Hydrophilic signals require to pass through plasma membrane?
Transmembrane receptor molecules
Why can’t Hydrophilic signals pass through the plasma membrane?
Hydrophilic molecules can’t pass through the hydrophobic membrane
The signal must be ______ across the membrane
transduced
What happens to the transmembrane receptors when the ligand binds?
The conformation changes
What role do transmembrane receptors have?
They act as signal transducers by converting the extracellular (outside the cell) ligand which alters the behaviour of the cell
What are the two ways hydrophilic signals can be transduced
- Cascades of phosphorylation by kinases
- Transmembrane proteins
What does phosphorylation cascades involve?
A series of events with one kinase activating the next in a sequence and so on
What can phosphorylation cascades result in?
The phosphorylation of many proteins as a result of the original signalling event
How are blood glucose levels maintained?
A negative feedback system involving the peptide hormones insulin and glucagon
Insulin allows fat and muscles cells to do what?
Absorb glucose from the bloodstream
How does glucose enter cells?
It passes into cells by travelling through transporter proteins in the plasma membrane (by facilitated diffusion)
What is GLUT4?
A transporter protein that allows glucose to enter cells
Binding of insulin to its receptor on the cell membrane causes what?
Binding causes a conformational change of the receptor which triggers phosphorylation of the receptor
What does the conformational change of the insulin receptor cause?
It starts a cascade of kinase phosphorylation inside the cell which leads to vesicles transporting GLUT4 to be moved to the cell membrane
What do the additional GLUT4 molecules allow?
They allow more glucose to enter the cell for further metabolism, allowing glucose to be controlled
