1l- Amino acid sequence determines protein structure

Question 1

What are proteins?

Answer 1

Polymers of amino acid monomers

Question 2

What are amino acids linked with to form polypeptides?

Answer 2

Peptide bonds

Question 3

Amino acids all have the same basic structure differing only in what?

Answer 3

The R group present

Question 4

What are the ways in which R groups can vary?

Answer 4

• size
• shape
• charge
• hydrogen bonding capacity
• chemical reactivity

Question 5

What are the four classifications of R groups?

Answer 5

• basic (positively charged)
• acidic (negatively charged)
• polar
• hydrophobic (non-polar)

Question 6

What does the wide range of functions carried out by proteins result from?

Answer 6

The diversity of R groups

Question 7

What is the primary structure of a protein?

Answer 7

The sequence in which the amino acids are synthesised into the polypeptide

Question 8

What results in secondary structure?

Answer 8

Hydrogen bonding along the backbone of the protein strand

Question 9

What are the three types of secondary structure?

Answer 9

• alpha helices
• parallel or anti-parallel beta sheets
• turns

Question 10

What does the tertiary structure of the protein involve?

Answer 10

The folding of the polypeptide chain to give a more complex 3D structure

Question 11

How is tertiary structure stabilised?

Answer 11

By interactions between the R groups

Question 12

What are the five interactions between the R groups that help stabilise tertiary structure?

Answer 12

• hydrophobic interactions
• ionic bonds
• LDF’s
• hydrogen bonds
• disulfide bridges

Question 13

What are disulfide bridges?

Answer 13

Covalent bond between R groups containing sulfur

Question 14

Where does quarternary structure exist and what does it describe?

Answer 14

It exists in proteins with two or more connected polypeptide subunits. It describes the spatial arrangement of the subunits

Question 15

What is a prosthetic group?

Answer 15

A non-protein unit tightly bound to a protein and are necessary for the proteins function

Question 16

What is an example of a prosthetic group?

Answer 16

The ability of haemoglobin to bind to oxygen is dependent on the non-protein haem group

Question 17

What can interactions between R groups be influenced by?

Answer 17

Temperature and pH

Question 18

What affect can temperature have on the interactions between R groups?

Answer 18

Increasing temperature disrupts the interactions that hold the protein in shape, and the protein begins to unfold, eventually becoming denatured

Question 19

What affect does pH have on the interactions between R groups?

Answer 19

The charges on acidic and basic R groups are affected by pH. As pH increases or decreases from the optimum, the normal ionic interactions are lost, which gradually changes the conformation of the protein until it becomes denatured