Question

1. Describe the concept of membrane fluidity. How is membrane fluidity altered with temperature and how organisms cope with that?

2. Membranes are asymmetric. Explain why

3. Describe the concept of membrane domains (e.g. enterocyte cells have multiple domains: apical, lateral and basal). Why is this relevant?  

Answer 1

ANS (1)- MEMBRANE FLUIDITY----->Lipid bilayer membrane structure is a quite rigid and stable structure but this structure also allows the phospholipid and sterol molecules to moves around within membrane, and leading to the fluidity(ability of substance to flow easily) of the membrane.

**ALTERATION OF MEMBRANE FLUIDITY WITH TEMPERATURE-

• Low temperature --->When the temperature goes down, membrane transform into solid state from liquid state that prevents the molecules to move rapidly and hence; resulting in  decrease of the membrane fluidity.
• High temperature--->When the temperature goes up, the membrane again reverse into liquid state from solid ones; resulting in rapid movement of molecule and increasing fluidity of the membrane. (this happens because fatty acid tails of the phospholipids become less rigid and allows more movement of protein and other molecules in and through the membrane).

**ORGANISM MODIFICATIONS TO DEAL WITH TEMPERATURE CHANGE (fluidity change)-

• bacteria and archaeal adapt some strategies to change their lipid compositions of their membrane to deal with temperature, as it influence the permeability of nutrients in/out of the membrane,
• They adapt Homeoviscous adaptation---> it is the adaptation process which allows cell membrane to maintain a liquid crystalline state at the low temperature to cause a membrane to enter the gel state.