• Ahmad Wagih Abdel (Halim)

Chromosomes and Genes

  • Chromosome: Each chromosome is formed of two parallel chromatids attached to each other by the centromere. Each chromatid is formed of a short and a long segment.

  • Diploid: Each human somatic cell contains 46 chromosomes (diploid cells), divided into 44 autosomal chromosomes and 2 sex chromosomes.

  • Haploid: Each human gamete cell contains only 23 chromosomes (haploid cells).

  • Gene: It is a segment in the chromatid. Its mirror image on the other chromatid of the same chromosome is known as allele.


  • It is a method used to visualize and evaluate the chromosomes and their disorders.

  • Technique: Lymphocytes are taken from the blood and are cultured in a cell excitatory medium. The cell cycle is arrested artificially at the metaphase of mitosis, where chromosomes are extracted and examined.

Barr Body

  • It is an inactivated X chromosome. Any cell in the human body should contain no more than one functioning X chromosome at a time. Any extraX chromosome is referred...


Down Syndrome Duchenne Muscular Dystrophy Lynch Syndrome Turner Syndrome Duchenne Muscular Dystrophy 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.McLaren Regional Medical CenterFlintUSA

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