Proteins

Question 1

what are proteins polymers of?

Answer 1

amino acids

Question 2

what are amino acids joined together by?

Answer 2

polypeptide bonds

Question 3

what is the structure of an amino acid?

Answer 3

• central carbon atom
• amine group
• hydrogen atom
• carboxyl group
• an ‘R’ group

Question 4

what is the primary structure of a protein?

Answer 4

• peptide bonds have formed between amino acids to form a long, straight chain (polypeptide)

Question 5

What is the secondary structure of a protein?

Answer 5

Hydrogen bonds form between nearby amino acids to form either an alpha helix or beta pleated sheet.

Question 6

What is the tertiary structure of a protein?

Answer 6

more bonds form between the different R groups to give the protein a 3D structure. R-group interactions involve hydrogen bonds, disulfide bonds, ionic bonds and polar interactions.

Question 7

What is the quaternary structure of a protein?

Answer 7

The structure formed from the interaction of multiple polypeptide chains held together by bonds.

Question 8

What is an example of a protein with a quaternary structure?

Answer 8

Haemoglobin
- consists of 4 polypeptide chains bonded together
-each chain surrounds an iron-containing haem group
-the haem group is referred to as a prosthetic group

Question 9

What are globular proteins?

Answer 9

• Globular proteins are spherical and arranged with their hydrophobic amino acids tucked inside and the hydrophilic amino acids exposed on the outside.
• This means globular proteins are soluble and can be transported easily from one part of the cell to another
  -They perform functional roles and include things like enzymes (such as amylase), hormones (such as insulin) or proteins like haemoglobin.
  -Globular proteins unravel and denature when the temperature or pH deviates from optimum levels
• Globular proteins with prosthetic groups attached (such as haemoglobin) are referred to as conjugated proteins.

Question 10

What are fibrous proteins?

Answer 10

-Long and thin and their primary structure consists of a repetitive sequence of amino acids.
-They perform structural roles so they are strong and insoluble
- fibrous proteins tend to be less sensitive than globular proteins to changes in temperature and pH

Question 11

What’s an example of a fibrous protein?

Answer 11

Collagen is a fibrous protein found in skin, bone and muscle. Its quaternary structure consists of 3 polypeptide chains held together by hydrogen bonds