Fluid Mosaic Model

Question 1

Fluid mosaic model

Answer 1

Proteins within membrane

Phospholipids can move within membrane

Glycolipids and glycoproteins
Cholesterol -regulates fluidity

Question 2

Functions of phospholipid bilayer

Answer 2

Allow lipid soluble substances to enter and leave
Prevent water soluble entering and leaving
Make membrane flexible and self resealing

Question 3

Explain how 3 features of a plasma membrane adapt it for its functions

Answer 3

Phospholipid bilayer
-acts as barrier preventing polar substances entering
Cholesterol
-increases strength + stability of membrane
Glycoproteins
-act as receptors

Question 4

What can pass through phospholipid bilayer

Answer 4

• Phospholipids and water don’t mix so the membrane prevents many water soluble substances getting through.
• Water is a polar molecule (the oxygen end is slightly negative and the hydrogen end slightly positive) – and can move through the membrane
• Charged molecules like ions cannot pass through the membrane
• Larger uncharged and molecules like glucose and polar chains of fatty acids cannot pass easily through the membrane and are transported by proteins
• Lipid soluble molecules can pass through