12th Zoology

Human Genetics – Karyotyping

Human Genetics – Karyotyping

Karyotyping is a technique through which the complete set of
chromosomes are separated from a cell and the chromosomes are lined up in
a karyogram. The term karyogram has now been replaced by another word
called Idiogram referring to a diagrammatic representation of chromosomes.

The karyological studies are usually made during mitosis, though the
chromosome structure and details can also be best done in meiotic
preparations. It is much easier to obtain and prepare suitable mitotic cells.

Mitosis also reveals the replicated chromosomes viz., sister chromatids. The diploid set of chromosomes in the eukaryotic cells has
constant morphological (phenotypic) features such as number, size, shape.

The chromosomes are identified by other features such as the
secondary constriction, arm ratio, and banding pattern. The summation of all
such characters, which identify a set of chromosomes is called

Karyotyping involves the culture of foetal cells found in the
amniotic fluid, in vitro, in a highly nutritive solution containing phytohaemagglutinin.

The foetal cells are cultured with colchicine. Colchicine stops
mitosis at metaphase. When these cells are subjected to a hypotonic
solution, the cells swell because the soluble salts are of lower concentration
than in normal protoplasm. The water diffuses into the cell and separates the

The scattered chromosomes are then placed on a slide, stained
and photographed under a microscope. Individual chromosomes are then
cut off from the photograph and marked as homologous pairs to form an


Related Topics in Zoology:

Bio Zoology All Important Topics

  1. MODERN GENETICS Introduction and Scope

  2. Human Genetics – Karyotyping

  3. Karyotyping of Human chromosomes

  4. Genetic Engineering

  5. Tools Of Genetic Engineering

  6. Restriction enzymes – Recombinant DNA Technology

  7. DNA – Segmenting / Fragmenting

  8. Genetic Diseases

  9. Human Genome Project (HGP)

  10. Cloning

  11. Transgenic organisms

  12. Gene Therapy

  13. Bioinformatics

  14. Scope of Genetic Engineering – Scope of Bioinformatics

  15. Database

  16. Genome sequencing

  17. Protein structure


    1. Human population and explosion

    2. Population Explosion

    3. Growing Population and Environmental impacts

    4. Global warming – Green house effect

    5. Ozone layer depletion

    6. Prevention and Effect of Ozone depletions

    7. Waste management – Classification

    8. Management of hazardous wastes

    9. Management of non hazardous wastes

    10. Waste water treatment and management

    11. Biodiversity

    12. Conservation of Biodiversity

    13. Characteristics of a Bioreserve

    14. Energy crisis and its environmental impact

    15. Steps to be taken to resolve energy crisis

    16. Environmental impacts of Power Sources

    17. Poverty and environment

    18. Fresh water crisis and management

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