BIOS 110: Membranes

What are the functions of biological membranes?

Specialized compartments, regulates reaction sequences, cell-cell recognition, and molecule binding for cell signaling.

Product of one enzyme equals:

Substrate for next enzyme

What are biological membranes mostly composed of?

Phospholipids, cholesterol, proteins, glycolipids, and glycoproteins

Which model is more accurate: Sandwich Model, or Fluid Mosaic Model?

Fluid Mosaic Model

Do saturated fatty acids have double or single bonds between carbons?

Single bonds

Do desaturated fatty acids have double or single bonds between carbons?

Double bonds

Does fatty acid saturation increase or decrease lipid fluidity?

Fatty acid saturation decreases lipid fluidity

Does fatty acid desaturation increase or decrease lipid fluidity?

Fatty acid desaturation increases lipid fluidity.

True or False: Long hydrocarbon tails make lipids more fluid, whilst short hydrocarbon tails make lipids less fluid.

False: Long hydrocarbon tails make lipids less fluid, as short hydrocarbon tails make lipids more fluid.

When the membrane becomes more fluid, it is:

More permeable

When the membrane becomes less fluid, it is:

Less permeable

True or false: Cholesterol maintains membrane integrity at extreme temperature conditions

True, it prevents too fluid/permeable membranes at warmer extreme warmer temperatures, and it prevents phospholipids from crystalizing at extreme lower temperatures.

Increase in temperature:

More fluid membranes

Decrease in temperature:

Less fluid membranes

What are membrane proteins?

Either peripheral (surface) or integral proteins.

What is the structure of an integral protein, and what does it do?

Alpha-helices with a hydrophilic end and hydrophilic core, which helps anchor proteins in a membrane.

What are glycolipids and glycoproteins used for?

Labels for packaging and distribution in the Golgi.

What is membrane diffusion?

Spontaneous movement of molecules from areas of high concentration to areas of low concentration.