Biological membranes

Question 1

what is the role of cell membranes?

Answer 1

Cell membranes act as barriers and control what passes into and out of cells and organelles

Question 2

describe the features of the cell membrane

Answer 2

These membranes are partially permeable. Only certain molecules are able to pass through. The components of the membrane determine which molecules are allowed through

Question 3

how do cell membranes have permeability?

Answer 3

Cell membranes achieve this permeability due to their structure — they are composed of phospholipids

Question 4

what is the cell membrane composed of?

Answer 4

The cell membrane is composed of two layers of phospholipids — this is called the phospholipid bilayer.

Question 5

what happens to the phospholipid bilayer and its components in aqueous conditions?

Answer 5

• In aqueous conditions, the hydrophilic heads form two outer rows while the hydrophobic tails are protected in a non-aqueous core.
• The phospholipid bilayer creates a partially permeable barrier and keeps the membrane fluid but stable.

Question 6

list the names of the components in the cell membrane

Answer 6

• phospholipids
• proteins
• glycoproteins
• glycolipids
• cholesterol

Question 7

why is the components in a cell membrane known as the fluid mosaic model?

Answer 7

• Its constituent components can move about conferring the membrane’s fluidity
• All the components differ in size and shape just like a mosaic

Question 8

what are the names of the 2 types of membrane proteins?

Answer 8

• integral (intrinsic proteins)

- peripheral (or extrinsic proteins)