Chapter 28, Problem 6P

(a)

Summary Introduction

To describe:

The effect of addition of high concentration of glucose in lac operon.

Introduction:

Operon can be defined as a set of adjacent structural genes with adjacent regulatory signals that affect transcription of the structural genes. Each operon is consisted of structural genes, promoter, operator, and so on.

(b)

Summary Introduction

To describe:

The effect of a mutation that prevents dissociation of the Lac repressor from operator.

Introduction:

In normal lac operon regulation, when the repressor is bound to lactose, it no longer binds to the operator DNA. Binding of lactose to the repressor alters the conformation of the repressor protein so that it does not have affinity for the operator.

(c)

Summary Introduction

To describe:

The effect of a mutation that completely inactivates $\beta \text{galactosidase}$ .

Introduction:

An operator is a DNA segment that turns the gene on and off. Its interaction with proteins increases or decrease the rate of transcription thus make an operon inducible or repressible.

(d)

Summary Introduction

To describe:

The effect of a mutation that completely inactivates galactosidase permease.

Introduction:

In the absence of lactose the repressor proteins binds to operator site and prevent the transcription. When the lactose is available it binds to the repressor protein and change the repressor shape, so that it cannot binds to the operator and structural genes are transcribed to produce proteins.

(e)

Summary Introduction

To describe:

The effect of mutation that prevents binding of $\text{CRP}$ to its binding site near the lac promoter

Introduction:

An operon is a functioning unit of genomic DNA containing a cluster of genes under the control of a single promoter. Operon occurs primarily in prokaryotes but also in some eukaryotes. Operon is made up of several structural genes arranged under a common promoter and regulated by common operator.