Proteins (B)

Question 1

What is the primary structure?

Answer 1

This refers to the sequence of amino acids in the polypeptide chain

Question 2

What does the sequence of amino acids determine?

Answer 2

The specific shape of the protein

Question 3

What type of chains are in the primary structure?

Answer 3

Long, straight chains

Question 4

What exactly is bonded in the primary structure?

Answer 4

The H from the amine groups and the C=O from the carboxyl groups

Question 4

What is the secondary structure?

Answer 4

Representing the folding or coiling of the polypeptide chain as a result of the hydrogen bonding between amine groups and carboxyl groups

Question 5

Why do proteins have such a wide variety of roles?

Answer 5

This is because tertiary structures are specific and unique

Question 5

What is the tertiary structure?

Answer 5

Further folding and coiling of the secondary structure, creating a unique 3D shape due to hydrogen bonds, ionic bonds and disulfide bonds.

Question 6

What types of secondary structures exist?

Answer 6

Alpha helix and Beta pleated sheet

Question 7

What does the tertiary structure of an enzyme determine?

Answer 7

The shape of its active site and its specific function

Question 8

What is the quaternary structure?

Answer 8

When proteins consist of more than one polypeptide chain

Question 9

What are the polypeptide chains held together by?

Answer 9

Hydrogen bonds, ionic bonds and disulfide bonds

Question 10

What are the two types of proteins?

Answer 10

Globular
Fibrous

Question 11

What are the features of globular proteins?

Answer 11

Are soluble in water
They include enzymes, antibodies and hormones
Consist of a highly folded and coiled polypeptide chain to produce a compact, complex tertiary structure

Question 12

What are the features of fibrous proteins?

Answer 12

Are insoluble in water
Is a secondary structure made up of long polypeptide chains which can form sheets or fibres
The fibres give strength while the sheets give flexibility
Their structural roles in the body are due to their strength and flexibility

Question 13

How is denaturation of a protein caused?

Answer 13

The breaking of hydrogen and ionic bonds
High temperatures above the optimum temperature
Extreme changes in pH
Heavy metals

Question 14

What is the denaturation of a protein?

Answer 14

An alteration in the tertiary structure of a protein
The loss of the 3D shape of the protein causes the protein to be no longer functional

Question 15

What is important to note about disulfide bonds strength?

Answer 15

They are not broken at the temperature which breaks hydrogen and ionic bonds. In some proteins the disulfide bonds can remain intact at temperatures as high as 70’C

Question 16

What is the test for proteins?

Answer 16

Add Biuret reagent
A purple or lilac colour indicates protein is present
If the solution remains blue, no protein is present