3.3 DNA Structure

Question 1

Outline DNA nucleotide structure

Answer 1

A DNA nucleotide is made up of a phosphate group, a deoxyribose sugar, and a nitrogenous base (can be one of four different bases).

Question 2

State the names of the four bases of DNA

Answer 2

Adenine, Guanine, Thymine, Cytosine.

Question 3

State the two purines

Answer 3

Adenine and Guanine

Question 4

State the two pyrimidines

Answer 4

Thymine and Cytosine

Question 5

Outline how DNA nucleotides are linked together into a single strand.

Answer 5

DNA nucleotides are linked together by a covalent bond between the deoxyribose sugar of one nucleotide, and the phosphate group of another.

Question 6

Outline the structure of a double helix

Answer 6

Two anti-parallel polynucleotide chains, held together by hydrogen bonds between the base pairs.

Question 7

State Adenine’s base pair

Answer 7

Thymine.

Question 8

State Thymine’s base pair

Answer 8

Adenine.

Question 9

State Guanine’s base pair

Answer 9

Cytosine.

Question 10

State Cytosine’s base pair

Answer 10

Guanine.

Question 11

Explain how a DNA double helix is formed

Answer 11

Formed through complementary base pairings (A+T, C+G). Pair’s held together by hydrogen bonds. This forms two polynucleotide chains.