Topic 1.3 Membrane Structure

Question 1

What are the functions of membrane proteins?

Answer 1

1. Hormone binding sites, 2. Immobilized enzymes with active site on the outside, 3. Cell adhesion to form tight junctions between groups of cells in tissues and organs, 4. Cell-to-cell communication, 5. Channels for passive transport to allow hydrophilic particles across by facilitated diffusion, 6. Pumps for active transport which use ATP

Question 2

Integral Proteins

Answer 2

Hydrophobic, in hydrocarbon chain

Question 3

Peripheral Proteins

Answer 3

Hydrophilic, on surface

Question 4

What is a Phospholipid Bilayer?

Answer 4

The outer cell membrane is formed by two layers of amphipathic phospholipids. They spontaneously arrange so the tail faces in and the head faces out.

Question 5

Explain the Fluid Mosaic Model.

Answer 5

The presence of proteins interspersed in the membrane that can move around.

Question 6

List aspects that supported Fluid Mosaic Model

Answer 6

1. Areas of weakness in the middle (hydrocarbon chains) interrupted by strong areas (transmembrane proteins), 2. Structure of membrane proteins vary in shape, 3. Some proteins are hydrophilic, 4. Fluorescent antibody tagging located proteins moved around the membrane.

Question 7

What did electron microscopy show Daveson and Danelli?

Answer 7

Led them to believe the membrane formed a sandwich.