Science, Grade 6


Table Of Contents: Chromosomes

1. Chromosome Location
Pairs of chromosomes are found in the nucleus of a cell. One chromosome from each pair is inherited from each parent.
2. Composition of Chromosomes
Chromosomes are made up of DNA (deoxyribonucleic acid), the hereditary material in humans and most other organisms.
3. Four Nitrogen Bases
The hereditary information in DNA is stored as a code of four nitrogen bases: adenine, guanine, cytosine, and thymine.
4. What Is a Gene?
Specific sections of the DNA are called genes. Each gene provides the cell with different information.
5. Number of Human Genes
Each chromosome is made up of many genes. There are about 100,000 genes found on human chromosomes.
6. Chromosome Number in Humans
In each human body cell, there are 46 chromosomes, existing in 23 pairs.