DNA Structure and History

Question 1

DNA History

Answer 1

1. Gregor Mendel: discovered inheritance of traits
2. Friedrich Miescher: discovered nuclein (DNA)
3. Avery, McCarty, McLeod: showed DNA was genetic material, not proteins
4. Erwin Chargaff: found base pairing rules
5. Rosalind Franklin: discovered crystal structure of DNA (double helix)
6. James Watson & Francis Crick: published structure of DNA

Question 2

Nucleotide Structure

Answer 2

Deoxyribose sugar with nitrogenous base attached at 1’ and phosphate group (negatively charged) attached at 5’

Question 3

Chargaff’s Rule

Answer 3

Adenine + Thymine with 2 H-bonds
Guanine + Cytosine with 3 H-bonds
G&A = purines (double-ringed)
T&C = pyrimidines (single-ringed)

Question 4

DNA Structure

Answer 4

Double helix structure: right-handed, turns every 10 nucleotides, antiparallel, 3’ ends in hydroxyl, 5’ ends in phosphate