Topic 2.6: DNA and RNA Structure

Question 1

Nucleotide

Answer 1

Monomer of a nucleic acid

Question 2

Components of a nucleotide (3)

Answer 2

1) A pentose sugar (Pentagon)
2) A phosphate group (Circle 5’)
3) A nitrogenous base (Rectangle 1’)

Question 3

Nucleic acid

Answer 3

The genetic material of the cell

Question 4

Types of Nucleic Acids (2)

Answer 4

1) DNA

2) RNA

Question 5

Nitrogenous basesa

Answer 5

Purines (Double O)
1) Adenine
2) Guanine
Pyrimidines (Single O)
1) Cytosine
2) Uracil
3) Thymine

Question 6

Linkage between nucleotides (2)

Answer 6

1) Nucleotides are linked together into a single strand via condensation reactions ( 5’-phosphate - 3’-hydroxyl)
2) Formation of a sugar-phosphate backbone that is covalently linked together by phosphodiester bonds

Question 7

DNA Structure (3)

Answer 7

1) Two complementary strands line up in opposite directions (anti-parallel)
2) Bases are facing inwards and connected by hydrogen bonds (G ≡ C and A = T)
3) The double stranded molecule then twists in order to adopt a more stable energy configuration (double helix)

Question 8

RNA Structure

Answer 8

Remains single stranded, but may fold upon itself to

form double stranded motifs

Question 9

DNA vs RNA

Answer 9

1) Deoxyribose | Ribose
2) Thymine | Uracil
3) Doble stranded | Single stranded

Question 10

Discovery of DNA Structure

Answer 10

Discovered by Watson and Crick in 1953

Question 11

Bases of DNA Model

Answer 11

1) DNA is composed of nucleotides made up of a sugar, phosphate and base
2) DNA is composed of an equal number of purines (A + G) and pyrimidines (C + T)
3) DNA is organised into a helical structure

Question 12

Deduction of DNA Structure

Answer 12

1) Double helix structure
2) Antiparallel DNA strands
3) Complementary base pairing (A=T, G≡C)