Structure of Membranes

Question 1

Where are membranes found?

Answer 1

Surrounding outside of cell.
Inside a cell surrounding an organelle.

Question 2

What is a phospholipid?

Answer 2

Phosphate group head (polar and hydrophilic)
Fatty acid chain tails (non-polar and hydrophobic)

Question 3

What does the phospholipid bilayer do?

Answer 3

Allows lipid- soluble substances to enter and leave cell.
Prevent water- soluble substances entering and leaving cell.
Makes the membrane flexible and self- scaling

Question 4

Role of intrinsic proteins

Answer 4

Transports across the membrane

Question 5

Role of channel protein

Answer 5

Allow passive movement of polar molecules and ions down conc gradient

Question 6

Role of carrier proteins

Answer 6

Play role in both passive and active transport in cells.
Involves shape of protein changing.

Question 7

Role of glycoproteins

Answer 7

Embedded in plasma membrane with attached carb chains.
Involved in cell adhesion and receptors for chemical signals.

Question 8

Role of glycolipids

Answer 8

Lipids attached with carb chains.
Act as cell markers.

Question 9

Role of cholesterol

Answer 9

Regulates the fluidity/ stability of membrane

Question 10

Role of steroids

Answer 10

Most functions as signalling molecules (hormones)
Maintains membrane structure and fluidity (reduces lipid mobility and widens membrane bilayer)