2.1.2m and n- Proteins

Question 1

What is the N- terminus?

Answer 1

in a polypeptide there is always one end with a free amino (NH2) group: this is called the N- terminus

Question 2

What is the C- terminus?

Answer 2

in a polypeptide chain, there is always a free end with a carboxyl (COOH) group: this is called the C- terminus

Question 3

What is the structure of proteins?

Answer 3

primary —-> secondary —-> tertiary —-> quarternary

Question 4

What is the primary structure of a protein?

Answer 4

The primary structure is the sequence of amino acids in a protein

Question 5

What is the secondary structure of a protein?

Answer 5

The secondary structure of a protein is formed when a chain of amino acids coil together to form an alpha helix or fold to form a beta pleated sheet (they both require H- bonding)

Question 6

What is the tertiary structure of a protein?

Answer 6

The tertiary structure of a protein is when the secondary structures fold together to form a very precise 3D shape

Question 7

What are the forces responsible for the formation of the tertiary structure?

Answer 7

• van der waal’s forces (hydrophilic and hydrophobic interactions)
• hydrogen bonds
• ionic bonds
• disulphide bonds

Question 8

What are van der waal’s forces?

Answer 8

• weak forces of attraction between non- polar groups or polar groups
• water excluded from these hydrophobic side chains helps keep the side chains together

Question 9

What is the quarternary structure of proteins?

Answer 9

the quarternary structures of proteins are composed of more than one polypeptide chain: the arrangement of the chains is the quarternary structure