M&R Session 1- The Membrane Bilayer Flashcards Preview

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Flashcards in M&R Session 1- The Membrane Bilayer Deck (8)
0

What are the five functions of biological membranes?

-continuous, highly selective permeable barrier
-control a chemical environment
-communication- between cells and their environment
-recognition- signalling molecules, adhesion proteins and immune surveillance
-signal generation- in response to a stimulus.

1

What is the dry weight membrane composition?

60% protein
40% lipid
1-10% carbohydrate
(20% water as membranes are hydrated structures)

2

What is the composition of a phospholipid?

Glycerol, 2 fatty acid side chains, a phosphate head group

3

How do fatty acids increase phospholipid membrane fluidity?

Unsaturated fatty acids contain a cis double bond which produce a kink. This reduces tightness of phospholipid packing and therefore increases membrane fluidity.

4

What does amphipathic mean?

Both hydrophobic and hydrophilic moieties

5

What four mobilities do membrane lipids have?

-flip-flop
-lateral diffusion within the bilayer
-flexion (vibration)
-axial rotation

6

What is the role of cholesterol within a membrane?

To stabilise it!

7

How does cholesterol perform its function?

-reduces membrane fluidity by binding to the carbonyl group of phospholipids and therefore reducing chain motion.
-increases membrane fluidity by binding to this carbonyl group and consequently decreasing tightness of packing of phospholipids.

Decks in SOPHIE'S ESA 2 Class (74):