3.2 - DNA Structure

Question 1

1944, Avery, McLeod, McCarty

Answer 1

• Proteins considered the hereditary molecule before the discovery of DNA
• Avery and his colleagues suggest that DNA, rather than protein as widely believed at the time, may be the hereditary material of bacteria
• When DNA of lethal S-strain extract was destroyed, R-strain did not take up toxic DNA and mouse lived

Question 2

Purine Nucleotides

Answer 2

• Contain a phosphate, deoxyribose sugar and a nitrogenous base
• Adenine and Guanine

Question 3

Pyrimidine Nucleotides

Answer 3

• Contain a phosphate, deoxyribose sugar and a nitrogenous base
• Cytosine and Thymine

Question 4

Erwin Chargaff

Answer 4

• molar ratio of Adenine to Thymine is 1:1

- molar ratio of Guanine to Cytosine is 1:1

Question 5

1953, James Watson and Francis Crick

Answer 5

-correctly described DNA structure

Question 6

Characteristics of DNA

Answer 6

• Double helix
• Hydrogen bonding (G-C 3H bonds, A-T 2H bonds)
• Complementarity
• Antiparallel
• sugar-phosphate backbone