KARYOTYPE:

The number size and shape of the chromosomes of a somatic cell arranged in a standard manner.

The normal human karyotype has 46 chromosomes

Chromosomes are described with the following categories:

Metacentric:

Acrocentric:

Telocentric:

Chromosomes are always arranged with the short arm on top

Standard nomenclature been developed for human chromosomes:

Paris nomenclature 1978

Human chromosomes are divided into 7 groups & sex chromosomes

Banded Human Karyotype

Difficult to distinguish between chromosomes without banding

Sources of tissue: blood-lymphocytes (mitogen phytohaemaggulatin), amniotic fluid, bone marrow, skin

Colchicine is used as a spindle arresting agent to accumulate metaphases

Differential staining of heterochromatic regions - assumed that the reagents differentially denature DNA reducing the amount of coiling

"Chromosomes & Karyotying" is installed in the network laboratories. It allows you to practice karyotyping, has a quiz and will be the basis for one of your practicals in BBT102.