Chapter 12, Problem 18P

Summary Introduction

To analyze:

In the given table, the partial diploid genotypes are tested for the following aspescts:

Complete the following table for production of $\text{β}$ galactosidase and permease in the presence or absence of lactose. Use ($\text{+}$) and ($\text{-}$) to indicate the presence of active enzyme and absence of active enzyme respectively. Determine the strain of partial diploid in lac ${}^{\text{+}}$ or lac ${}^{\text{-}}$.

Introduction:

In the lac operon, the partial diploids are produced by conjugation between $\text{F'}\text{× F}$; it will have two copies of the part of genome, hence, they are partially diploid. The lac operon partial diploids contain one copy of the lac operon information in the recipient bacterial chromosome and a second copy of it picked up by the $\text{F'}$ plasmid. The genotypes of the partial diploids are written in a fashion that on left side, the $\text{F'}$ segment is written, and on the right side recipient chromosome is written, and these are separated and indicated by ($\text{/}$).

Based on the studies of structural gene mutations, Jacob, Monod, and Colleagues concluded that lac $\text{+}$ and lac $\text{-}$ requires two protein-producing genes i.e. lacZ and lacY.

These two wild type alleles are always dominant to the mutant type alleles.