Genetics: DNA History and Discovery

Question 1

What happened for DNA in 1869? (J Frederich Miescher)

Answer 1

First person to isolate DNA. Named it nucleic acid (Was acidic + found in nucleus)

Question 2

What happened for DNA in the 1920’s?

Answer 2

Scientists discover chromosomes contain DNA (hereditary material)

Question 3

What happened for DNA in the early 1900’s? (Phoebus Levene)

Answer 3

RNA and DNA discovered. Shown they were made of nucleotide chains. Both contain a 5 ring carbon sugar, phosphate group, and 1 of 4 nitrogen bases (GACT). RNA contains U not T. Incorrectly suggested there were equal amounts of these bases.

Question 4

What happened for DNA in 1928? (Frederick Griffith)

Answer 4

Discovery of DNA’s function began when testing smooth and rough bacteria strains on mice.

• Dead smooth/live rough killed no mice
• Mixed killed mice
• Dead smooth’s factor transformed live rough into live smooth (transformation)
• Concluded transforming factor had genetic information

Question 5

What happened for DNA in 1944? (Avery, McCarty, and MacLeod)

Answer 5

Identified previous transforming factor as DNA and not a protein. Suggested DNA was the hereditary substance.

• Heat killed pathogen bacteria transformed when treated with protein destroying enzyme, but not DNA destroying

Question 6

What happened for DNA in 1951? (Chargaff)

Answer 6

Was discovered the nitrogen based ration in cells relates to genetic codes (A = T , C = G)

Question 7

What happened for DNA in 1950-1951? (Rosland Franklin)

Answer 7

Repeating structures in DNA discovered after crystallography was used on it.

Question 8

What happened for DNA in 1952? (Hershey and Chase)

Answer 8

Experiments conducted on bacteriophages using radioactive tracers. Conclusively discovered DNA as (Griffith’s) a transforming factor. DNA entered bacteria to take over, not protein.

Question 9

What happened for DNA in 1953-1964? (Watson and Crick)

Answer 9

The 3-D double helix shape of DNA was discovered and DNA code,