The structure of DNA and RNA

Question 1

How many polynucleotide strands does DNA have?

Answer 1

Two polynucleotide strands

Question 2

What is the overall structure of DNA

Answer 2

It has:

• a sugar-phosphate backbone
• with bases in the centre

Question 3

What bond is the two polynucleotide strands held together by and where do they form?

Answer 3

Hydrogen bonds which form on opposite strands

Question 4

What are the bases complimentary to?

Answer 4

The bases on one strand are complimentary to the bases on the other strand

A purine base on one strand is complimentary to a pyrimidine on the opposite strand

Question 5

What is important about the distance between the sugar-phosphate backbone?

Answer 5

That it is constant all down the DNA molecule

Question 6

What is meant by the term anti-parallel?

Answer 6

The polynucleotide strands in DNA run in opposite directions

Question 7

What is the relationship between base pairs and the number of hydrogen bonds they form?

Answer 7

Different base pairs form different hydrogen bonds

Question 8

How many hydrogen bonds does Guanine and Cytosine form?

Answer 8

3 hydrogen bonds

Question 9

How many hydrogen bonds does Adenine and Thymine form?

Answer 9

2 hydrogen bonds

Question 10

What are the proportions between complimentary base pairs?

Answer 10

The same proportions

Question 11

What are some key differences between DNA and RNA?

Answer 11

DNA is found in chromosomes in the nucleus. RNA is found in the cytoplasm

DNA is a very long molecule. RNA is a very short molecule

DNA has two polynucleotide strands in a double helix. RNA has is single stranded- has one polynucleotide strand

RNA has Uracil instead of Thymine