Genetic Variation In Bacteria Extra

Question 0

How does conjugation occur?

Answer 0

One cell produces a thin projection that met pets another cell and forms a conjugation tube

The donor cell replicates one of its small circular pieces of DNA

The circular DNA is broken up to make it linear before it passes along the tube into the recipient cell

This linear strand then forms a circle in the recipient cell (new plasmid)

Question 1

Diversity in bacteria arises from changes to its DNA. How do these changes occur?

Answer 1

Mutation

Recombination (conjugation)

Question 2

In 1946 Joshua Ledeberg carried out experiments designed to demonstrate that genes could be transferred between different strains of the bacteria E.coli
How was this carried out?

Answer 2

Strain 1 - can’t synthesise methionine and biotin so would only grow if these were added to the medium

Strain 2 - can’t synthesis threonine and leucine so would only grow if these were added to the medium

The strains would grow in the minimal medium when grown together

Question 3

What is the minimal medium?

Answer 3

A growth medium that contains only the basic nutriens

Question 4

What is the supplementary medium?

Answer 4

Jelly like substance to which nutrients have been added (it has been supplemented)