Karyotype

Definition

A karyotype is the complete set of chromosomes in a cell, organized and displayed in a standard format. It is used to study chromosomal abnormalities and variations in number or structure.

5 Must Know Facts For Your Next Test

1. Karyotypes are typically prepared from cells at metaphase when chromosomes are most condensed.
2. A normal human karyotype contains 46 chromosomes, including 22 pairs of autosomes and one pair of sex chromosomes.
3. Karyotyping can help diagnose genetic disorders like Down syndrome, which has an extra chromosome 21.
4. Chromosomes in a karyotype are arranged by size, banding pattern, and centromere position.
5. Techniques such as G-banding stain chromosomes to reveal distinct patterns used for identification.

Review Questions

• What phase of the cell cycle are cells usually in when preparing a karyotype?
• How many total chromosomes are found in a normal human karyotype?
• What genetic disorder is characterized by an extra chromosome 21?

Related terms

Autosome: Chromosomes that are not sex chromosomes; humans have 22 pairs.

Sex Chromosome: Chromosomes involved in determining the sex of an individual; humans have one pair (XX or XY).

G-Banding: A technique that uses specific stains to produce visible bands on chromosomes for easier identification.