Question

Also, How far apart are the bob and billy genes that control growth in the absence of BOB and BILLY nutrients? Explain your reasoning.

.(4 points) Strain A of bacteria is an Hfr strain that can grow on minimal media without added nutrients, but is sensitive to killing by Ampicillin (genotype Hfr AmpSbobt billyt joet). Strain B of bacteria is an F- strain that is resistant to Ampicillin, and needs the nutrients BOB, BILLY, and JOE added to minimal media in order to grow (genotype Ampbob- billy joe"). You mate these two strains and then interrupt the mating with a blender at various times and plate the bacteria onto different kinds of media. After 5 minutes of mating, you see bacteria growing on minimal media with Amp, BOB and BILLY (but no JOE). After 12 minutes you see colonies growing on minimal media with Amp, JOE, and BILLY (but no BOB). After 22 minutes you see colonies growing on minimal media with Amp, JOE and BOB. How far apart are the joe and bob genes? Explain your reasoning.

Answer 1

In the interrupted mating technique, the conjugation bridge is intentionally broken to stop the mating between the Hfr strain and F strain at different time intervals to determine the order and time of the gene transfer.

In the experiment mentioned above, the linear transfer of genes is determined.

Strain A Hfr Cell Strain-B F-strain Am Amp Silly + Bog Tout Amp Linear Transfer of genes

The gene which enters first would show higher concentration as the time interval is increased. This can be determined using the graph given below:

Freq. y Mfr characters among recombinanto (%) Time Eminutes) BILLY Bart Joet

the graph determines the order of genes transferred: JOE-BOB-BILLY

when these genes are mapped on the plasmid DNA as shown in the figure given below

Joet es er BOB 1000 5 (12) 3o BILLY (22)

it can be found that the transfer of JOE takes place at 5 minutes, BOB at 12 minutes and BILLY at 22 minutes.

This shows that the distance between JOE and BOB genes is 7minutes while BOB and BILLY genes are 10 minutes apart from each other.