Membranes & transport - fluid mosaic model

Question 1

What do membranes form between the cell and its environment?

Answer 1

Partially permeable barriers

Membranes also form barriers between cytoplasm and organelles and within organelles.

Question 2

Name the processes by which substances can cross membranes.

Answer 2

• Diffusion
• Facilitated diffusion
• Osmosis
• Active transport

These processes allow for the movement of substances across cell membranes.

Question 3

How do membranes play a role in cell signalling?

Answer 3

By acting as an interface for communication between cells

This facilitates interactions and responses in cellular environments.

Question 4

Who first outlined the fluid mosaic model of membranes?

Answer 4

Singer and Nicolson in 1972

This model explains the arrangement of biological molecules in cell membranes.

Question 5

What does the fluid mosaic model help to explain?

Answer 5

• Passive and active movement between cells and their surroundings
• Cell-to-cell interactions
• Cell signalling

These aspects are critical for understanding cell behavior and communication.

Question 6

Why are cell membranes described as ‘fluid’?

Answer 6

Because the phospholipids and proteins can move around within their own layers

This fluidity is essential for membrane function.

Question 7

Why are cell membranes described as ‘mosaics’?

Answer 7

Because the scattered pattern produced by the proteins within the phospholipid bilayer resembles a mosaic when viewed from above

This characteristic highlights the diverse composition of membranes.

Question 8

List the four main components of the fluid mosaic model.

Answer 8

• Phospholipids
• Cholesterol
• Glycoproteins and glycolipids
• Integral and peripheral proteins

Each component plays a specific role in membrane structure and function.