Using donor DNA from an E. coli strain of leu+ arg+ trp- you transform a resipient strain that is leu- arg- trp+ and select for leu+. The resulting 100 colonies are then screened for the arg and trp markers and the results are outlined in the table below.

genotype # of colonies
1. arg+ trp+ 8
2. arg- trp- 47
3. arg+ trp- 18
4. arg- trp+ 27

Determine the order of the genes and relative map distances.

To determine the order of the genes and their relative map distances, we can use the method of cotransduction. Cotransduction is the process in which two genes are transferred together from one bacterium to another via bacteriophages (viruses that infect bacteria).

In this experiment, we transformed a leu- arg- trp+ recipient strain using donor DNA from an E. coli strain with the genotype leu+ arg+ trp-. We then selected for colonies that acquired the leu+ marker. Now, we have 100 colonies, and we need to analyze their genotypes to determine the order and distances of the arg and trp markers.

We can use the following formula to calculate the cotransduction frequency:

Cotransduction frequency (%) = (Number of cotransductants / Total number of transductants) × 100

To calculate the map distances, we can use the formula:

Map distance between two genes = Cotransduction frequency between two genes / Total number of cotransductants × 100

Now, let's apply these formulas to the given data:

1. arg+ trp+ colonies: 8
2. arg- trp- colonies: 47
3. arg+ trp- colonies: 18
4. arg- trp+ colonies: 27

To calculate the cotransduction frequency between arg and trp, we need to determine the number of cotransductants. Cotransductants are the colonies that received both the arg and trp markers from the donor DNA.

From the data given, we can see that 8 colonies are arg+ trp+, 47 colonies are arg- trp-, 18 colonies are arg+ trp-, and 27 colonies are arg- trp+. To find the number of cotransductants (arg+ trp+), we need to subtract the number of non-cotransductants (arg- trp- colonies) from the total number of colonies:

Number of cotransductants = arg+ trp+ colonies = 8

Now, we can calculate the cotransduction frequency and the map distance:

Cotransduction frequency between arg and trp = (Number of cotransductants / Total number of transductants) × 100 = (8 / 100) × 100 = 8%

Map distance between arg and trp = Cotransduction frequency between arg and trp / Total number of cotransductants × 100 = (8 / 8) × 100 = 100%

Therefore, based on the data provided, the order of the genes is leu- trp- arg+. The map distance between trp and arg is 100%, indicating that these two genes are closely linked and rarely separated during the recombination process.