Biosignalling

Question 1

Describe the four types of intercellular signalling.

Answer 1

Endocrine = signalling molecules travel to other cells via the blood stream.

Paracrine = signalling molecules act on cells in the immediate surrounding area.

Neuronal = signalling molecules travel across a synapse to receptors on target cell.

Contact dependent = signalling molecules expressed on cell surface and bind to receptors on another when they come into contact.

Question 2

What is the difference between fast and slow cell response?

Answer 2

Fast = ms/minutes - altered protein function leads to altered cytoplasmic behaviour / cell response.

Slow = minutes/hours - altered gene expression leads to increased/decreased or new protein synthesis, leads to altered cytoplasmic behaviour / cell response.

Question 3

List the cell-surface receptor types.

Answer 3

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

Question 4

What is the general pathway for activation of an intracellular response?

Answer 4

1. Hormone carried to tissue via serum binding protein, and diffuses across cell membrane.
2. Hormone binds to intracellular receptor in nucleus, causing dimerization with other hormone-receptor complexes.
3. This binds to
   Hormone Response Elements in the DNA.
4. These HREs are adjacent to specific genes.
5. Dimerized receptor attracts coactivator/corepressor proteins that regulate transcription of adjacent gene.
6. Increased/decreased mRNA production alters production of corresponding protein, which produces cellular response.