Chromosomes and Genes: An Introduction

Chromosomes are not visible in the cell’s nucleus—not even under a microscope—when the cell is not dividing. However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope. Chromosome is composed of DNA coiled and condensed around nuclear proteins called histones. Humans inherit one set of chromosomes from their mother and a second set from their father. In total, most human cells contain 46 chromosomes with 22 pairs of autosomes, or non-sex chromosomes, and two sex-determining chromosomes. The sex chromosomes in humans are called X and Y. Females carry two X chromosomes, while males carry one X and one Y chromosome. Cells of the body that contain two sets of chromosomes are called diploid.

Gene: It is a linear sequence /segment of DNA that provides the coded instructions for synthesis of RNA, which, when translated into protein, leads to the expression of hereditary character.

Source of info.

1. http://www.nature.com/scitable/topicpage/introduction-what-is-dna-6579978

https://ghr.nlm.nih.gov/primer/basics/chromosome

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