Types of Proteins 3.7

Question 1

Globular Proteins

Answer 1

They are compact, soluble and usually spherical. They fold so their hydrophobic R-groups are in the centre, protected from water and their hydrophilic R-groups are on the outside

Question 2

Insulin

Answer 2

This is a globular protein that is used to regulate blood glucose concentration in the blood. It is a spherical shape and is soluble so it ca be transported around the bloodstream.

Question 3

Conjugated proteins

Answer 3

These are like globular proteins but they also contain a prosthetic group. This is a non-protein e.g a haem group.

Question 4

Haemoglobin

Answer 4

This is a protein that is made from 4 polypeptides and is used to transport oxygen around the blood. The haem group contains iron 2+ ions that binds to oxygen and can carry it around the body.

Question 5

Catalase

Answer 5

This is an enzyme made of 2 subunits that has haem groups that bind to hydrogen peroxide which is a byproduct of metabolism and can be toxic if not broken down, catalse breaks it down

Question 6

Fibrous proteins

Answer 6

These are long, insoluble molecules that have their hydrophobic R-groups in their primary structures and are exposed. They are normally long, strong molecules and not folded into 3D structures

Question 7

Keratin

Answer 7

Found in hair, skin and nails. It has lots of disulfide binds which makes it very hard and inflexible. It depends how many disulfide bonds it has, hair has less of them than nails which is why it’s more flexible

Question 8

Elastin

Answer 8

This is found in the walls of blood vessels or in the alveoli as they need to be elastic and flexible. It is a quaternary protein and made from stretchy molecules called tropoelastin

Question 9

Collagen

Answer 9

This is found in the skin and ligaments. They are made from 3 polypeptides that are twisted together into a rope like structure that is usually flexible.