5. Intergrative mechanisms: chemical signalling

Question 1

What is an autocrine signalling molecule?

Answer 1

Binds to receptors and exerts its effects on the cells that produces it

Question 2

What are the 2 extracellular signalling molecules?

Answer 2

Cell surface receptors - molecules too large or too hydrophilic to cross the cell membrane rely on membrane receptors
Intracellular receptors- molecules that are small enough or hydrophobic pass through the membrane & directly activate intracellular receptor protein

Question 3

What are features of receptors?

Answer 3

Proteins 
Specific for one molecule
Activated by agonists 
Blocked by antagonists 
Divided into classes for any one agonist

Question 4

What are the three different cells that induce different responses due to chemical signalling?

Answer 4

Heart muscle cell
Salivary glands
skeletal muscle cell

Question 5

What are the three stages of cell signalling?

Answer 5

1. Reception
2. Transduction
3. Response

Question 6

What are the 3 main classes of cell surface receptors?

Answer 6

G-protein coupled receptors
Enzyme linked receptors
Ion channel-linked receptors

Question 7

What are the 3 main classes of cell surface receptors?

Answer 7

G-protein coupled receptors
Enzyme linked receptors
Ion channel-`linked receptors

Question 8

What are the features ion channel-linked receptors?

Answer 8

Is either a part of an ion channel or is a separate protein near the channel
Opens/closes in response to the binding of its signal molecule
Converts chemical signals into electrical signals
Is a speciality of excitable cells

Question 9

What are the features G-protein linked receptors?

Answer 9

1. The G-protein is inactive when it is attached to a GDP molecule
2. A signal molecule binds to the receptor, which changes shape and binds to the inactive G-protein. A GTP molecule displaces the GDP, and activates the G-protein
3. The activated G-protein binds to another enzyme and activates it to it to initiate a cellular response.
4. The G-protein hydrolyses the GTP and returns to inactive state

Question 10

Look at adreneline as a signalling molecule

Answer 10

look at the slides around this topic

Question 11

What happens when intercellular communication fails?

Answer 11

Developmental disorders
Diseases
Cancer
Death