Module 2: Types of Proteins

Question 1

Name the three main types of protein

Answer 1

globular
fibrous
conjugated

Question 2

Describe the features of fibrous proteins…

4 points

Answer 2

-they are long insoluble molecules
-they form due to having a high proportion of amino acids with hydrophobic R groups in their primary structure
-their amino acid sequence is usually quite repetitive
-they tend to make strong long molecules which don’t fold into 3D structures

Question 3

Give 3 examples of a fibrous protein

Answer 3

keratin

elastin

collagen

Question 4

Describe the structure of keratin and state where this protein is mainly present

Answer 4

-in hair skin and nails

-its a strong , inflexible , insoluble protein with a high proportion of disulfide bridges

Question 5

Describe the role of elastin in the body

Answer 5

-makes up part of the walls of blood vessels and the alveoli which provides them with the flexibility to expand and return to normal size

Question 6

Describe the structure and role of collagen in the body

Answer 6

-has many different forms but all consist of 3 polypeptide chains that form a long rope structure

-makes up connective tissue that is found in the skin , in tendons , ligaments and the nervous system

Question 7

Describe the main features of a globular protein…

4 points

Answer 7

-they are compact , water soluble , spherical molecules
-they form when proteins fold into their tertiary structure and their hydrophobic R groups are kept away from the aq environment
-the hydrophilic R groups are on the outside of the protein making it water soluble
-they are essential for regulating life processes such as chemical reactions , immunity and muscle contractions

Question 8

Name 3 globular proteins and describe their roles and/or structures in the body

Answer 8

insulin-a hormone involved in the regulation of blood glucose concentration

catalase-is a quaternary protein containing 4 haem groups
-the iron ions in the haem groups allow catalase to interact with hydrogen peroxide and catalyse its breakdown

haemoglobin-is a quaternary protein made from 2 alpha and 2 beta sub units , each sub unit contains a haem group and iron ions are able to combine reversibly with oxygen

Question 9

What is a conjugated protein?

Answer 9

a protein that contains a prosthetic group