Question Abacterial strain is able to grow on rich medium wh

Question Abacterial strain is able to grow on rich medium (which contains all the amino acids, vitamins, and a variety of carbon sources) but not on minimal medium oron minimal medium supplemented with leucine. What could be the genotype(s) of this bacterial strain with respect to the angand Mouloci? Answer leu or arg Abu

Solution

1)

The bacterial strain must be growing in the presence of all aminoacids and it might have arg^-leu^-. But, leucine can be synthesized from the other protein sources of the bacteria. So, the bacteria can also have the genotype of arg⁺leu^-.

2)

The minimal medium has to consist of streptomycin and sodium azide to select the E.Coli recombinants of genotype gly⁺azi^Rstr^R. If sodium azide and streptomycin are present in the medium, those colonies that have grown are said to be resistant to those two compounds. Those that have grown in the absence of glycine in the medium are said to have that gene.

3)

From the given options, the F^- bacterial strain that has ala⁺leu⁺ can be selected by growing them on the minimal medium that has streptomycin.

4)

CO transduction frequency also should be less than 1%.

If the distance between the two genes is very less, then there is higher possibility of them getting co-transduced. SO, the answer is very high and almost 100 percent.

5)

Answer is a-c-b, c is closer to b than to a.

As the co-transduction frequency is higher between b and c, they are very close to each other.

As the co-transduction frequency is higher between a and c and lower between a and b, a is closer to c than to b.

So, a cannot be between b and c, it has to be after c. The gene order can be written either as a-c-b or b-c-a. Nevertheless, it is evident that c is close to b than to a as c-b has co-transduction frequency of 65% and c-a has 20%.