DNA Structure

1. Outline: nucleotide structure in terms of:

sugar = deoxyribose

nitrogenous base

phosphate group

2. State the names of the four nitrogenous bases in DNA:

adenine

guanine

thymine

cytosine

3. Outline how the DNA nucleotides are linked together by covalent bonds into a single strand

backbone: deoxyribose - phosphate - deoxyribose - phosphate

nitrogenous base attached to deoxyribose

4. Explain: how a DNA double helix is formed using:

complementary base paring:

A = T: adenine forms two hydrogen bonds with its complementary base, thymine

G = C: guanine forms three hydrogen bonds with its complementary base, cytosine

hydrogen bonds:

the combination of hydrogen bonds between A = T and G = C hold the two strands of DNA together

each strand forms a helix, the two strands together form a double helix

5. Draw a simple diagram of the molecular structure of DNA