Chapter 7: 7.1 Types of Cell Signalling

Question 1

Cell signalling overview:

What is cell signalling often used for?

Answer 1

Sensing environmental signals and trigger a response in the cell

Question 2

Cell signalling overview:

Cell signalling is often in the form of…

Answer 2

A ligand

(A small molecule)

Question 3

Cell signalling overview:

What does the ligand bind to?

Answer 3

A receptor on the surface of the cell
* Often spans the membrane so that part of the receptor is facing the inside of the cell can transfer the signal

Question 4

Cell signalling overview:

Where does the signal go once the ligand binds to a receptor?

Answer 4

1. Can be picked up by an intermediate receptor called a transducer
2. Can go directly to a response regulator which triggers an intracellular response

Question 5

Cell signalling overview:

What are intercellular responses?

Answer 5

Signals that are shared between cells
* They get converted to intracellular responses within the cell

Question 6

What are the steps to cell signalling?

Answer 6

1. Synthesis of signalling molecule
2. Transport of the signalling molecule to target cell
3. Bind to a specific receptor
4. Start signal-transduction pathway (pathway of signals in the cell) to elicit a response

Question 7

Define:

Autocrine Signalling

Answer 7

Cell releases signals for itself

Question 8

In autocrine signalling:

What is the ligand?

Answer 8

Often a hormone or chemical messenger

Question 9

In autocrine signalling:

What do the ligands bind to?

Answer 9

Autocrine receptors on the same cell that made them

Question 10

Give an example of autocrine signalling

Answer 10

Certain immune cells produce secreted proteins that activate their own maturation process

Question 11

Define:

Paracrine Signalling

Answer 11

Communication between local cells

Question 12

In paracrine signalling:

What are the signals released as?

Answer 12

Ligands released as a chemical compound

Question 13

True or False:

Paracrine signalling only affects the cell itself

Answer 13

False, they only affect cells close to each other

Question 14

Give an example of paracrine signalling

Answer 14

Nerve cell sends signals to local muscle cells to contract

Question 15

Define:

Gap Junction Signalling

Answer 15

Signalling happens between cells that have direct contact to each other

Question 16

What do gap junction signalling often have?

Answer 16

Protein channels that span the membranes of both cells
* Connect the cells in tight gap junctions which mean nothing including water can pass through the gap

Question 17

In gap junction signalling:

How does signalling occur?

Answer 17

Signalling molecules can travel between the protein channels to trigger intracellular responses

Question 18

Give an example of gap junction signalling

Answer 18

Transfer of apoptosis (mediated cell death) signals

Question 19

What are forms of paracrine signalling?

Answer 19

• Paracrine signalling
• Gap junction signalling

Question 20

Define:

Synaptic Signalling

Answer 20

Signalling between nerve cells called neurons

Question 21

Describe:

How synaptic signalling works

Answer 21

• Neurons release signalling molecules (neurotransmitters) into the synapse (area between cells)
• The neurotransmitters are picked up by the receptor in another neuron to transfer down the signal

Question 22

What form of signalling is synaptic signalling?

Answer 22

Paracrine signalling

Question 23

Describe:

Endocrine Signalling

(3 points)

Answer 23

• Long distance signalling
• Signalling molecules are released into the bloodstream and travel to the site of signalling
• Ligands are often in the form of hormones

Question 24

Summarize of the signalling systems

Answer 24

• Autocrine: A cell targets itself
• Gap junction: A cell targets a cell connected by gap junctions
• Paracrine: A cell targets a nearby cell
• Endocrine: A cell targets a distant cell through the bloodstream