Membranes

Question 1

Components of cell membranes

Answer 1

1. Phospholipid
2. Cholesterol
3. Glycolipid

Question 2

Describe the structure of cholesterol

Answer 2

1. Hydrophobic and hydrophilic region
2. Hydrophobic region interacts with hydrophobic hydrocarbon chains of phospholipid molecules
3. Interconnecting rings
   - rigid => membrane fluidity

Question 3

Function of cholesterol

Answer 3

@normal temp:
-restrains the movement of phospholipid and makes membrane less fluid

@cold temp:
-prevents solidification by hindering the close packing

Question 4

Structure and function of glycoproteins

Answer 4

Structure:
-phospholipids with short chains of sugar residues covalently attached to them

Function:

• recognition sites for
  1. neurotransmitter and hormones
  2. Adhesion bt cells

Question 5

What are the three types of membrane proteins?

Answer 5

1. Surface protein
2. Integral protein
3. Glycoprotein

Question 6

Structure and function of surface protein

Answer 6

Struc:

• attached to surface not embedded
• easily detached from membrane
• in contact with aq. medium => hydrophilic

Functions:

1. Structural support
2. Election carriers
3. Carrier molecules

Question 7

Structure and function of integral proteins

Answer 7

Structure:

• penetrate through
• held in place by strong hydrophobic and hydrophilic interactions
• hydrophobic midsections

Functions:

1. Structural support
2. Electron carriers
3. Carrier molecules

Question 8

Function of cell membrane

Answer 8

1. Boundary b.t. intercellular and extracellular environment
2. Regulates the movement of substances
   - selective permeable
3. Cell signalling and communication
4. Compartmentalisation within cells
5. Formation of Multiple ES-complexes