lecture 3.3 - Birth of molecular biology

Question 1

What did Muller do?

Answer 1

Muller was the first mutagenesis (x-ray mutagenesis)
Flies exposed to x-rays had loads of offspring with mutant characteristics
Can now use genetics to study interest
x-rays damage chromosomes.

Question 2

What did Auerbach do in the 1940s?

Answer 2

Auerbach was a chemical mutagenesis.
He saw that mustard gas was a mutagenic and that soldiers exposed to mustard gas had caused their offspring to have birth defects
Auerbach saw that the mustard gas affect genes and inheritability.
He found that the gas hadn’t affected proteins but DNA. And this hinted towards the importance of DNA in chromosomes.

Question 3

Who was George Beadle and what did he and his group hypothesise?

Answer 3

George Beadle worked in genetics and biochemistry.
He and his group worked with bread mould (Neurospora crassa). The mould underwent meiosis - all products were held together in an ascus.

The mould was carefully analysed and they formed a detailed genetic mapping.

The mould was grown on a plate in a controlled environment
mutations in genes corresponded with inability to make one enzyme
plotted the pathway of the enzyme
‘one gene, one enzyme concept’

Question 4

Luria and Delbrock

Answer 4

Look at infective events, used bacteriophage
could map mutations inside a gene

showed protein coat of the bacteriophage was left outside the bacteria but DNA went inside

mutations weren’t a direct result of the environment - they can be good or bad

Question 5

Esther Lederberg

Answer 5

Using replica plating - was able to confirm Luria and Delbrooks findings

mutations could be mapped within a gene
happened spontaneously - not a result of environment

Question 6

Avery experiment/ Hershey & Chase

Answer 6

Experiments with phage to conclusively show that it was the DNA that contributed the hereditary information to the next generation

guided and informed Watson and Crick