In studies of recombination between mutants 1 and 2 from Problem 21, the results shown in the following table were obtained.

When mutant 6 was tested for recombination with mutant 1, the data were the same as those shown above for strain B, but not for K12. The researcher lost the K12 data but remembered that recombination was ten times more frequent than when mutants 1 and 2 were tested. What were the lost values (dilution and plaque numbers)?

Verified step by step guidance

1. Step 1: Understand the problem. The goal is to determine the lost values (dilution and plaque numbers) for the recombination frequency between mutant 6 and mutant 1 on E. coli K12. The problem states that recombination was ten times more frequent than the recombination frequency between mutants 1 and 2.
2. Step 2: Calculate the recombination frequency for mutants 1 and 2 on E. coli K12. Use the formula for recombination frequency: \( \text{Recombination Frequency} = \frac{\text{Number of Recombinant Plaques}}{\text{Total Plaques}} \). From the table, the number of plaques for mutants 1 and 2 on K12 is 8, and the dilution is \( 10^{-2} \).
3. Step 3: Multiply the recombination frequency of mutants 1 and 2 by 10 to find the recombination frequency for mutants 6 and 1 on K12. This is because the problem states that recombination was ten times more frequent for mutants 6 and 1.
4. Step 4: Use the new recombination frequency to calculate the number of plaques for mutants 6 and 1 on K12. Rearrange the recombination frequency formula to solve for the number of plaques: \( \text{Number of Plaques} = \text{Recombination Frequency} \times \text{Total Plaques} \). Assume the same dilution factor (\( 10^{-2} \)) unless otherwise specified.
5. Step 5: Verify the results by ensuring that the calculated recombination frequency for mutants 6 and 1 is indeed ten times the recombination frequency for mutants 1 and 2. This step ensures consistency and correctness in the calculations.

Key Concepts

Recombination Frequency

Recombination frequency refers to the rate at which genetic recombination occurs between two loci during meiosis. It is often expressed as a percentage or a ratio, indicating how often offspring inherit a combination of alleles different from their parents. In this context, understanding recombination frequency is crucial for interpreting the results of mutant interactions and predicting the outcomes of genetic crosses.

Mutant Phenotypes

Mutant phenotypes are observable traits resulting from genetic mutations that alter the normal function of genes. In the context of the question, the phenotypes of the E. coli strains (r and +) indicate different genetic characteristics that can affect recombination rates. Recognizing how these phenotypes relate to the underlying genetics helps in analyzing the data and understanding the implications of the recombination results.

Dilution and Plaque Assays

Dilution and plaque assays are techniques used to quantify the number of viral particles or bacterial colonies in a sample. In this scenario, the dilution factor indicates how much the original sample was diluted, while the number of plaques represents the number of successful infections or colonies formed. These measurements are essential for calculating recombination frequencies and understanding the relationship between the mutants and their phenotypes.