Lecture 16

Question 1

What are local cell signalling mechanisms?

Answer 1

Contact, cell-cell signalling, paracrine, autocrine, synaptic

Question 2

What are long distance cell signalling mechanisms?

Answer 2

Endocrine, neuronal

Question 3

Why is signal transduction good?

Answer 3

Allows massive amplification therefore very low amounts of hormones/neurotransmitters can be effective

Question 4

what is an example of intracellular receptors and local signalling gases?

Answer 4

1. Steroid hormones

2. Nitric oxide

Question 5

What are G-protein coupled receptors (GPCRs)?

Answer 5

1000s of receptors controlling heart rate, vision, smell. They span the membrane 7 times.

Question 6

How do G-Protein Coupled Receptors work?

Answer 6

Contain GDP which is bound to alpha subunits, the activation of the G-Protein by GPCRs swaps GDP for GTP. The active G-Protein then transmits the signal. The signal is turned off by the hydrolysis of GTP –> GDP

Question 7

What else can G-Proteins do?

Answer 7

They can activate enzymes that generate second messengers in the cell e.g. cAMP

Question 8

What are Enzyme Coupled Receptors?

Answer 8

Receptor Tyrosine Kinases - span the PM once, they are receptors that phosphorylate tyrosine amino acids

Question 9

Differences between GPCR and RTK

Answer 9

GPCR are faster.

Question 10

What are steroid hormones?

Answer 10

Receptors for steroids found in cytosol

Question 11

What are Nitric Oxide triggers for?

Answer 11

Smooth muscle relaxation, it generates cyclic GMP