Structure of plasma membrane

Question 1

Outline features of the plasma membrane that allow it to be referred to as fluid mosaic.

Answer 1

• Fluidity: Lipids and proteins move within the bilayer, making the membrane flexible.
• Mosaic: The membrane contains a mix of proteins, lipids, and carbohydrates arranged in a patchwork pattern.
• Phospholipid Bilayer: The hydrophilic heads and hydrophobic tails create a flexible barrier.

Question 2

Explain the terms hydrophilic and hydrophobic, ensuring you refer to the components of the phospholipid in your explanation.

Answer 2

• Hydrophilic refers to the “water-loving” part of a phospholipid, which is the phosphate head. It attracts water.
• Hydrophobic refers to the “water-fearing” part, which is the fatty acid tail. It repels water.

Question 3

Explain the function of cholesterol in the plasma membrane.

Answer 3

Cholesterol helps stabilize the plasma membrane by maintaining its fluidity, preventing it from becoming too rigid or too fluid.

Question 4

Describe the term semipermeable.

Answer 4

Semipermeable means that the membrane allows certain substances to pass through while blocking others.

Question 5

Outline the purpose of integral proteins found in the membrane.

Answer 5

Integral proteins help transport substances across the membrane, act as receptors, and contribute to cell signalling.