6 - DNA Is The Genetic Material

Question 1

Garrod proposition

Answer 1

proposed that in both cases of albinism and alkaptonuria, there was a defective inheritable factor for a metabolic step

Question 2

auxotroph def

Answer 2

a mutant that requires a particular additional nutrient

Question 3

prototroph def

Answer 3

the normal strain which does not require that certain additional supplement

Question 4

Beadle and Tatum’s experiment - 1941

Answer 4

came to the “one gene: one enzyme (one protein/function) hypothesis - that the genetic code is complementary
- demonstrated multiple genes for a pathway

Question 5

Friedrich Miescher 1869

Answer 5

discovery of nucleic acids by investigating the nuclei of leukocytes
- proposed that a substance called ‘nuclein’ may be the basis of hereditary

Question 6

Griffith Experiments - 1928 - outline the experiments and interpretations from each

Answer 6

R cells of pneumonia - non-pathogenic
S cells - pathogenic - secrete a polysaccharide capsule

1. The first control:
   - inject mouse with living R cells
   - mouse remains healthy
   - living R cells recovered from mouse
   - R cells survive in mice, but dont cause pneumonia
2. Second Control:
   - inject mouse with living S cells
   - mouse gets pneumonia
   - living S cells recovered from heart tissue
   - so S cell survive in mice, and cause pneumonia - pathogenic
3. third control
   - mouse injected with heat-killed S cells
   - mouse remains healthy
   - no living S cells recovered from heart tissue
   - so dead S cells dont cause pneumonia
4. the experiment aim:
   - mouse injected with micture of heat-killed S cells and living R cells
   - mouse dies
   - S and R cells recovered from mouse heart tissue
   - S cell transforming principle that survives heat treatment has altered some of the R cells - possible reproduced with them etc.