Chapter 12, Problem 14STP

Summary Introduction

To find out:

The number of chromosomes in the organisms karyotype with a monosomy of chromosome 3.

Introduction:

The study of genetics does not involve study of genes alone. Scientists also study chromosomes by using images of chromosomes stained during metaphase. Chromosomes are the structures that contain the genetic material that are passed from generation to generation of cells. The pairs of homologous chromosomes are arranged in order of decreasing size to produce a micrograph called karyotype.

Answer to Problem 14STP

The karyotype of the given organism will show 5 chromosomes due to only one copy of chromosome 3.

Explanation of Solution

Nondisjunction during meiosis may result in gametes with abnormal number of chromosomes. Cell division during which sister chromatids fail to separate properly is called nondisjunction. If an offspring has a set of three chromosomes of one kind, it is called trisomy. Having only one of a particular type of chromosome is called monosomy. Monosomy occurs due to nondisjunction either in meiosis I or meiosis II.

The given organism has diploid number of chromosomes as 6. So there are 3 pairs of chromosomes out of which chromosome 3 has only one of the pair of chromosomes due to monosomy. Hence the total number of chromosomes that can be seen in the karyotype of the organism is 5.