T2L2 Cell Membranes

Question 1

What is the main component of the plasma (cell) membrane and describe its features

Answer 1

Phospholipid bilayer

Phospholipid molecules are made of a polar hydrophilic head (phosphate) and the non polar hydrophobic tails. The tails are clustered together on the inside of the membrane and the heads on the outside.

Question 2

What forms due to the structure of phospholipids

Answer 2

Micelles

Question 3

Explain the fluid mosaic model

Answer 3

The components in the membrane are free to move around like a sea

Question 4

Explain proteins in the membrane

Answer 4

Some proteins are on the inside of the membrane some proteins are on the outside of the membrane - some span the whole membrane.

Many of the proteins are transport proteins: Channel and Carrier proteins

Channel proteins are like pores in the membrane

Carrier proteins change shape to pass the molecule across the membrane

Question 5

Explain the role of cholesterol in the membrane

Answer 5

hydrophobic and hydrophilic regions stop some molecules from passing through the membrane

cholesterol stops the phospholipids from moving around so provides stability

Question 6

Compare glycolipids and glycoproteins and their functions

Answer 6

Glycolipids are phospholipids with sugar molecules attached. They have a similar function to glycoproteins - they also act as recognition sites and antigens.

Glycoproteins: these are proteins with sugar molecules attached. They act as recognition sites and antigens