M&R Session 1- The Membrane Bilayer Flashcards

0
Q

What is the dry weight membrane composition?

A

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

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1
Q

What are the five functions of biological membranes?

A
  • 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.
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2
Q

What is the composition of a phospholipid?

A

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

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3
Q

How do fatty acids increase phospholipid membrane fluidity?

A

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

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4
Q

What does amphipathic mean?

A

Both hydrophobic and hydrophilic moieties

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5
Q

What four mobilities do membrane lipids have?

A
  • flip-flop
  • lateral diffusion within the bilayer
  • flexion (vibration)
  • axial rotation
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6
Q

What is the role of cholesterol within a membrane?

A

To stabilise it!

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7
Q

How does cholesterol perform its function?

A
  • 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.
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