Chapter 8, Problem 1TQ

Summary Introduction

The human genome contains 46 chromosomes (23 pairs) and they carry the genetic information. The 22 pairs of chromosomes are known as autosomes, each pair in the autosomes carries the same genes or genetic information except the sex chromosomes such as X and Y chromosomes. The X and Y chromosomes are involved in the determination of sexual characteristics in human beings.

Answer to Problem 1TQ

Two homologous chromosomes contain the same genes found at the same loci but may have the same or different copies of alleles.

Explanation of Solution

Chromosomes: The double helical DNA molecule is wrapped around histone proteins and the structure is known as a chromosome.  Chromosomes contain genes and carry genetic information. There are 46 chromosomes and 23 pairs of homologous chromosomes are present in humans. Homologous chromosomes are a pair of chromosomes and they found to be similar based on their size, physical character, pattern, centromere location, gene position and content. The offspring receives one chromosome from the mother and other from the father.

Genes: Genes are considered as a basic unit of the genetic information or heredity. The gene is composed of DNA sequence and that code for specific genetic characteristic. The size of genes differs from a few hundred to two million bases.

Loci: The physical location of genes on the chromosome is known as loci (singular “locus”). Homologous chromosomes contain a similar kind of genes in their corresponding loci.

Alleles: Alleles are different versions of a gene. In the diploid cell, two different alleles of a gene can present in a given locus on the pair of homologous chromosomes.