Biological membranes, fluid-mosaic model, lipid properties

Question 1

Fluid-Mosaic

Answer 1

Fluid - individual lipid molecules move
Mosiac - diverse ‘particles’ penetrate the lipid layer

Question 2

Fluid-Mosaic Model

Answer 2

Structure of Biological Membranes

It is the bilayer of amphipathic lipids
Proteins: Integral (Transmembrane)

Question 3

Classes of Membrane Proteins

Answer 3

Integral (membrane proteins)
Peripheral (membrane proteins)
Lipid-Anchored (membrane proteins)

Question 4

Biological Membranes

Answer 4

Functions:
- Define cell boundary (plasma membrane)
- Define/enclose compartments
- Control movement of material into and out of the cell
- Allow response to external stimuli
- Enable interactions between cells
- Provide scaffold for biochemical activities

Question 5

Plasma Membrane

Answer 5

• Trilaminar structure
• Made of phospholipid bilayer
• Amphipathic molecules, meaning they have hydrophobic and hydrophilic regions

Question 6

Integral (transmembrane) proteins

Answer 6

They are permanently embedded into the lipid bilayer
- Transport of nutrients and ions
- Cell-cell communication (gap junction)
- Attachment

Question 7

Peripheral membrane proteins

Answer 7

Require protein anchors to hold them up
- Temporarily associated with the membrane
Can associate on either side/all surfaces of the lipid bilayer

Question 8

Lipid-anchored membrane proteins

Answer 8

• Covalently attached to lipid in the bilayer
• Can be detached by an enzyme

Question 9

Lipid properties

Answer 9

• Hydrophobic
• Good stores of energy for cells
• Saturated or unsaturated