Cell Structure: Membrane Proteins

Question 1

What are the 2 main categories of CSM proteins?

Answer 1

-Intrinsic (integral)
-Extrinsic (peripheral)

Question 2

Describe a Intrinsic Protein.

Answer 2

A protein fully embedded from one side of the membrane to the other side and have hydrophobic amino acids on the outside surfaces of the protein.

Question 3

What do the hydrophobic amino acids do?

Answer 3

They interact with the hydrophobic fatty acid tails in the phospholipid bilayer.

Question 4

What are the 2 types of intrinsic proteins?

Answer 4

-Carrier proteins
-Protein Channels

Question 5

What are Protein Channels?

Answer 5

Intrinsic proteins containing a channel running through their centre. The channel is lined with hydrophilic amino acids and is filled with polar water molecules.

Question 6

What do the hydrophilic amino acids within the protein channel’s channel allow them for?

Answer 6

Allows water-soluble molecules/ions to diffuse through.

Question 7

What are Carrier Proteins?

Answer 7

Intrinsic proteins which can change shape and position to transfer hydrophilic molecules/ions across a membrane.

Question 8

What are Extrinsic Proteins?

Answer 8

Proteins which do not span the membrane, and are found on either one side of the membrane or the other side.

Question 9

What can extrinsic proteins sometimes be attached to?

Answer 9

Intrinsic proteins.

Question 10

What are the 3 key functions of extrinsic proteins?

Answer 10

-Play a structural role within the membrane.
-Act as enzymes
-Be receptors for other molecules.

Question 11

Give an example of an other molecule that extrinsic proteins can be receptors for?

Answer 11

Hormones.

Question 12

What can many membrane proteins have attached to them?

Answer 12

Carbohydrate molecule.

Question 13

What does a protein with a carbohydrate molecule attached form?

Answer 13

Glycoprotein.

Question 14

What are the 3 key functions of Glycoproteins?

Answer 14

-To allow cells to attach to each other, in order to form tissues , e.g. Nervous Tissue.
-To play a role in the Immune System, by presenting Antigens to T-Cells.
-Some act as Receptors for hormones.