CELL SIGNALLING AND CYTOKINES

Question 1

What are the different types of cell signalling

Answer 1

Paracrine signalling
Autocrine signalling
Endocrine signalling

Question 2

What is paracrine signalling

Answer 2

The signalling molecules manufactures by the original cell target cells very close by

Question 3

Example of paracrine signalling

Answer 3

Synaptic transmission

Gap junctions- contact dependent

Question 4

What is synaptic transmission

Answer 4

Example of paracrine. Signalling

Electrical and doesn’t involve changes in chemical concentrations

Question 5

Advantages of synaptic transmission

Answer 5

Communications between neutrons involves a chemical messenger across synaptic cleft
No dilution in general circulation
System can by reactivated very quickly

Question 6

Disadvantages of synaptic transmission

Answer 6

Specificity
Hardwiring is expensive
Possibly vulnerable

Question 7

Advantages of gap junctions (contact dependent )

Answer 7

Allow the movement of ions
Allow the movement of metabolites and intercellular signalling molecules
Essential in embryonic development

Question 8

Disadvantages of contact dependent signalling

Answer 8

Can only communicate with adjacent cells
Relatively slow transmission across an organ
Potential transmission of deleterious factors from one cell to another

Question 9

What is contact dependent signalling

Answer 9

Also know as gap junctions
Cells can communicate via cytoplasmic bridges which allow signalling molecules to pass between cells without being secreted into the extra cellular fluid

Question 10

What is autocrine signalling

Answer 10

Self signalling, the signalling molecules target the same cell they were manufacture at

Question 11

What is endocrine signalling

Answer 11

Signalling molecules (hormones ) utilise the circulatory system to target cells far away from the regional manufacturing cell

Question 12

How is signal specificity achieved

Answer 12

Signalling molecules must match the active site of the target cell (either receptor or cell to cell contact )

Question 13

What causes the formation of lipid rafts

Answer 13

Interactions between lipids generate the formation off lipid rafts
Very important in cell signalling

Question 14

What holds together the phospholipid bilayer

Answer 14

Held together by hydrophobic interactions

Question 15

What are cytokines

Answer 15

Soluble proteins or glycoproteins produced by cells

Are the most important signalling molecules

Question 16

What do cytokines do

Answer 16

Mediate and regulate immunity (innate and adaptive ), haematopoesis and embryogenesis
Regulate inflammation - either pro-inflammatory or anti-inflammatory

Question 17

How are cytokines produced

Answer 17

Are released by cells

Mainly produced de novo , however some are stored as precursors

Question 18

What does pleiotrophy mean

Answer 18

Same cytokines can bind to multiple cells

Each cell= different reaction and different outcome

Question 19

What does redundancy mean in terms of cytokines effects

Answer 19

2 or more cytokines have the same or similar effects on a cell

Question 20

What does synergy mean in terms of cytokines effects

Answer 20

The combined effect can be greater/ additive compared to the actin of each cytokines alone

Question 21

What does antagonism mean in terms of cytokines effects

Answer 21

One cytokines inhibits the activity of another

Question 22

What does cascade activation mean in terms of cytokines effects

Answer 22

One cytokine may induce a cascade of cytokine expression involving multiple cells

Question 23

Why are cytokines self limiting and brief

Answer 23

If the stimulus is removed they stop - rarely act alone

This is because the RNA produced is unstable allowing transient expression

Question 24

What does cell signalling coordinate

Answer 24

Movement 
Metabolism 
Growth
Development 
Immune response

Question 25

What can the effects of cytokines be

Answer 25

Pleiotrophy
Redundancy
Synergy
Antagonism
Cascade activation