Topic 2b- Cell membrane structure

Question 1

Describe the fluid mosaic model.

Answer 1

The fluid mosaic model is one way of understanding biological membranes, consistent with most experimental observations. This model states that the components of a membrane such as proteins or glycolipids, form a mobile mosaic in the fluid-like environment created by a sea of phospholipids.

Question 2

What do the phospholipids do?

Answer 2

Form a barrier to dissolved substances.
They have a head and a tail
Head is hydrophilic- attracts water
Tail is hydrophobic- repels water
The molecules automatically arrange them into a bilayer. The heads face outwards.

Question 3

What does the cholesterol do?

Answer 3

Type of lipid. Fit between phospholipids. They bind to the hydrophobic tails, causing them to pack more closely together. Restricts movement of the phospholipids, making the membrane less fluid and more rigid.
Cholesterol helps to maintain the shape of animal cells.

Question 4

Explain why the plasma membrane can be described as having a fluid mosaic structure.

Answer 4

It is a mosaic of components that move freely and fluidly in the plane of the membrane.