Proteins - Retrieval Questions 3

Give an example of a transport proteins.

Haemoglobin

Give an example of a hormone.

Insulin

Give an example of an enzyme.

Pepsin

Define globular protein

It is a protein with a spherical shape that is soluble in water. They usually have metabolic roles.

Where is haemoglobin found?

In red blood cells.

What is the role of haemoglobin?

To transport oxygen from the lungs to the body tissues.

What structure does haemoglobin have?

A quaternary structure.

Why does haemoglobin have a quaternary structure?

Because it is made up of four polypeptide chains.
It has two alpha globin and two beta globin.

Why is haemoglobin also described as a conjugated protein?

Because it has a prosthetic group attached to each polypeptide chain.

What is a prosthetic group?

It is a non-protein component that is necessary for the protein to carry out its function.

What are prosthetic groups in haemoglobin called?

They are called haem groups.

What do the haem groups contain?

An iron ion.

How many oxygens can haemoglobin tranport?

Haemoglobin can transport 4 oxygen molecules. this is because one oxygen molecule can bind to each haem group.

What is insulin?

It is a globular protein that is secreted by the pancreas.

What is the role of insulin?

The role of insulin is to maintain blood glucose concentrations.

What is insulin composed of?

It is composed of two polypeptide chains. One chain is alpha helix, the other is beta pleated sheet.

What are the two polypeptide chains in insulin joined together with?

Disulphide links.

How is the shape of insulin relevant to its function?

The shape of insulin allows it to specifically bind to receptors on cell membranes to help lower blood glucose concentrations.

Why is insulin soluble in water?

Because it has a hydrophilic r group on the outside.

Why is it good that insulin is soluble?

So that it can dissolve in blood and be easily transported around the body.