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Chromosome

• Overview

Definition:

Chromosomes are long pieces of DNA found in the center (nucleus) of cells. DNA is the material that holds genes . It is considered the building block of the human body.

Information:

Chromosomes come in pairs. Normally, each cell in the human body has 23 pairs of chromosomes (46 total chromosomes). Half come from the mother; the other half come from the father.

Two of the chromosomes (the X and the Y chromosome) determine if you are born a boy or a girl (your gender). They are called sex chromosomes:

• Females have 2 X chromosomes.
• Males have 1 X and 1 Y chromosome.

The mother always contributes an X chromosome to the child. The father may contribute an X or a Y. Therefore, it is the father that determines the gender of the child.

The remaining chromosomes are called autosomal chromosomes. They are known as chromosome pairs 1 through 22.

Related topics:

• Autosomal dominant
• Autosomal recessive
• Genetic counseling and prenatal diagnosis
• Sex-linked dominant
• Sex-linked recessive

For detailed information, see heredity and disease (genetics).

• Review Date: 1/16/2007
• Reviewed By: Brian Kirmse, MD, Mount Sinai School of Medicine, Department of Human Genetics, New York, NY. Review provided by VeriMed Healthcare Network.

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