Chapter 21, Problem 6P

Interpretation Introduction

(a) Interpretation:

The average human chromosome contains about $1\times {10}^8$ bp of DNA. If each base pair has a mass of about $660\text{daltons}$ and there are about $\text{2}\text{g}$ of protein (histones plus non-histones) per gram of DNA, the weight of such a chromosome should be calculated in grams.

Concept introduction:

Compaction ratio is the ratio of extended length to actual length. Length of total DNA is the product of extended average length of DNA, total number of chromosomes per cell and total number of cells. On dividing total DNA length by the distance between the Sun and the Earth, the ratio of the lengths is obtained.

Interpretation Introduction

(b) Interpretation:

The length of extended DNA should be calculated.

Concept introduction:

Compaction ratio is the ratio of extended length to actual length. Length of total DNA is the product of extended average length of DNA, total number of chromosomes per cell and total number of cells. On dividing total DNA length by the distance between the Sun and the Earth, the ratio of the lengths is obtained.

Interpretation Introduction

(c) Interpretation:

An actual chromosome is about $\text{5}\text{μm}$ long. The approximate compaction ratio is to be determined.

Concept introduction:

Compaction ratio is the ratio of extended length to actual length. Length of total DNA is the product of extended average length of DNA, total number of chromosomes per cell and total number of cells. On dividing total DNA length by the distance between the Sun and the Earth, the ratio of the lengths is obtained.

Interpretation Introduction

(d)Interpretation:

You have about $4\times {10}^{12}$ cells in your body. If you have $46$ chromosomes in each cell, the approximate extended length of your entire DNA should be calculated. For comparison, the distance from the earth to the sun is about $1.5\times {10}^8\text{km}$.

Concept introduction:

Compaction ratio is the ratio of extended length to actual length. Length of total DNA is the product of extended average length of DNA, total number of chromosomes per cell and total number of cells. On dividing total DNA length by the distance between the Sun and the Earth, the ratio of the lengths is obtained.