1.4 Hydrophillic Signalling

Question 1

Where do hydrophilic signaling molecules bind

Answer 1

Transmembrane receptors

Question 2

Do hydrophilic signaling molecules enter the cytosol

Answer 2

No

Question 3

Give examples of hydrophilic signaling molecules

Answer 3

Peptide hormones and neurotransmitters

Question 4

Transmembrane receptors change conformation when

Answer 4

The ligand binds to the extra cellular face

Question 5

How does the signal get across the plasma membrane

Answer 5

It is transduced

Question 6

Transmembrane receptors act as signal transducers… how

Answer 6

They convert extracellular ligand binding events into intracellular signals

Question 7

What do transduced hydrophilic signals often involve

Answer 7

G proteins and cascades of phosphorylation by kinase enzymes

Question 8

What is the function of a G protein

Answer 8

To relay signals from activated receptors to target proteins such as enzymes and ion channels

Question 9

What do phosphorylation cascades allow

Answer 9

More than one intracellular signaling pathway to be activated
Can result in the phosphorylation of many proteins as a result of the original signaling event

Question 10

Explain fully the events of hydrophilic signaling

Answer 10

Hydrophilic signaling molecules bind to transmembrane receptors and do not enter the cytosol
Transmembrane receptors change conformation when the ligand binds to the extracellular face
The signal is transduced across the plasma membrane- the ligand binding event is converted into intracellular signals, altering the behavior of the cell
Transduced hydrophilic signals often involve G proteins or cascades of phosphorylation by kinase enzymes.
An example of hydrophilic signaling molecules are neurotransmitters