DNA and RNA

Question 1

Give two types of nucleic acid

Answer 1

1. DNA (deoxyribonucleic acid)
2. RNA (ribonucleic acid)

Question 2

What are the monomers of DNA and RNA?

Answer 2

Nucleotide

Question 3

What is the structure of a nucleotide?

Answer 3

A pentose sugar, a phosphate group and a nitrogen-containing organic base

Question 4

What is the structure of a DNA nucleotide?

Answer 4

A pentose sugar called deoxyribose, a phosphate group and one of four bases - adenine (A), thymine (T), cytosine (C) and guanine (G)

Question 5

What is the structure of an RNA nucleotide?

Answer 5

A pentose sugar called ribose, a phosphate group and one of four bases - adenine (A), uracil (U), cytosine (C) and guanine (G)

Question 6

How is a polynucleotide formed?

Answer 6

The nucleotides join up via condensation reactions between the phosphate group of one nucleotide and the sugar of another. This forms a phosphodiester bond (consisting of a phosphate group and two ester bonds). This chain of sugars and phosphates is known as the sugar phosphate backbone

Question 7

Explain the double-helix structure of DNA

Answer 7

Two DNA polynucleotides join together by hydrogen bonding between the bases. Each base can only. join with one other - complimentary base pairing. A always bonds with T. C always bonds with G. This means there are equal amounts of A+T and C+G. Two H bonds form between A+T and three H bonds form between C+G. Two antiparallel polynucleotide chains twist to form the DNA double helix

Question 8

How is an RNA polynucleotide different to a DNA polynucleotide?

Answer 8

RNA is made from a single polynucleotide chain and it’s much shorter than DNA polynucleotides