week 6 - cell signalling

Question 1

what is cell signalling

Answer 1

is the ability for cells to receive, process and trigger a response

Question 2

Name and briefly describe 3 types of cell signalling

Answer 2

1. Local signalling: the cell releases a signal that affects itself or nearby cells
2. Long distance signalling: the cell releases a signal (in the form of a hormone) that is put into the bloodstream and then distributed throughout the body
   3.

Question 3

Give 4 examples of signalling molecules or “first messengers”.

Answer 3

ions, hydrophillic molecules like adrenaline, hydrophobic molecules like testosterone, proteins like the human growth hormone

Question 4

What are intracellular receptors? Give one example.

Question 5

What happens to the three-dimensional structure of receptors upon ligand binding? Give an
example of what happens when an ion-channel receptor binds to its ligand?

Question 6

what are the 3 steps in cell signalling

Answer 6

1. signal reception 2. signal transduction. 3. cellular response

Question 7

Briefly describe the 2 types of cell signalling?

Answer 7

1. direct contact via cell junctions: animal and plant cells have cell junctions that allow signalling molecules to pass readily between the 2 adjacent cells without crossing the plasma membrane
2. cell surface molecules on adjacent cells interact with each other, resulting in a signal passing between the cells (e.g. immune responses)

Question 8

what is paracrine signalling?

Answer 8

cells nearby the cell producing a signal are affected by the release of this signal. This means that adjacent cells have receptios that perceive the signal from the secretory cell.

Question 9

what is autocrine signalling?

Answer 9

this is when the same cell releases a chemical signal, but has receptors that bind that signal and can then intiate cascades. This is a sign of a positve feedback loop.

Question 10

what is synaptic signalling?

Answer 10

This is when an electrical signal triggers the release of neurotransmitter molecules, which diffuse across a synaptic gap to the target cell to intiate a response.

Question 11

How do ions cross the cell membrane?

Answer 11

through channels in the membranes hat allow the ions to move into the side of the cell

Question 12

How do lipophillic molecules cross the membrane?

Answer 12

they can pass through the cell membrane by diffusion

Question 13

How do hydrophillic molecules cross the membrane

Answer 13

There is receptor on the surface of the receiving cell that can transmit the signal inside to the cell