30.4 DNA

Question 1

What is the full name of DNA

Answer 1

Deoxyribonucleic acid

Question 2

What are monomers of DNA

What are these made of

Answer 2

Nucleotides are made of 3 components

• Pentose sugar
• Phosphate
• Base

Question 3

What are the 4 different types of bases

Answer 3

Adenine
Thymine
Cytosine
Guanine

Question 4

Describe the polymerisation of nucleotides

Answer 4

• Two nucleotides link when the OH group of a phosphate on one nucleotide reacts with an -OH group on a sugar molecule on another nucleotide to eliminate a molecule of water
• More nucleotides add on in the same way to form a polymer chain which has sugar phosphate backbone

Question 5

Describe double helix of DNA

Answer 5

• Two strands held together by hydrogen bonds
• Bases adenine and thymine bond together
• Guanine and cytosine bond together

Question 6

Why is adenine thymine bond weaker than cytosine guanine

Answer 6

A-T bond is a double bond whilst C-G bond is triple

Question 7

What happens to DNA during cell division

Answer 7

• The hydrogen bonds of DNA double helix break and strands start to unravel but the covalently bonded chain remains in tact retaining the sequence of bases
• The cell contains a mixture of separate nucleotide molecules which attach to their complimentary pair on the strand

So two new double helix molecules are made

Question 8

How is DNA used

Answer 8

• It codes for proteins which are the basis of living things