Introduction

Eukaryotic organisms organize their DNA content into physical segments called chromosomes.  Humans have a total of 46 chromosomes, 22 pairs of homologous chromosomes along with 2 sex chromosomes.

Let us learn a little bit more about the organizations of genes along chromosomes.

What is a gene versus an allele? The following video explains the difference.

Summary

In this section, we have learned the following:

• Genes are discrete segments of DNA which code for specific proteins in the cell.
• Alleles are alternate forms of the same gene.
• Mutations result when changes occur to the DNA sequence of a gene.  Mutations are the ultimate source of all new alleles.
• Homozygous – two alleles of a gene are identical between the two chromosomes.
• Heterozygous –  two alleles of a gene are different between the two chromosomes.

Sources:

“Alleles and Genes.” Kahn Academy. Retrieved from https://youtu.be/P0nMnPPdW_k_Licensed under: Standard YouTube License