Chapter 24, Problem 15P

(a)

Summary Introduction

To describe: The reason why $\sigma =0$ lane in gel A has multiple bands.

Introduction:

Gel electrophoresis is a technique by which the DNA fragments could be separated based on their size and charge. The samples are loaded in the well which is separated based on their charge in between the positive and negative electrodes. When the current passes through the gel, molecules moves across the gel according to their charge.

(b)

Summary Introduction

To determine: In gel B, whether the DNA from the $\sigma =0$ preparation positively or negatively supercoiled in the presence of intercalating dye.

Introduction:

Gel electrophoresis is a technique by which the DNA fragments could be separated based on their size and charge. The samples are loaded in the well which is separated based on their charge in between the positive and negative electrodes. When the current passes through the gel, molecules moves across the gel according to their charge.

(c)

Summary Introduction

To determine: The reason for the presence of relaxed DNA in these lanes. As given, in both gels, the $\text{σ}\text{=}-\text{0}\text{.115}$ lane has two bands, one highly supercoiled DNA and one relaxed.

Introduction:

Gel electrophoresis is a technique by which the DNA fragments could be separated based on their size and charge. The samples are loaded in the well which is separated based on their charge in between the positive and negative electrodes. When the current passes through the gel, molecules moves across the gel according to their charge.

(d)

Summary Introduction

To determine: The approximate superhelical density of the native DNA.

Introduction:

Gel electrophoresis is a technique by which the DNA fragments could be separated based on their size and charge. The samples are loaded in the well which is separated based on their charge in between the positive and negative electrodes. When the current passes through the gel, molecules moves across the gel according to their charge.