Paste this page into your notebook & glue the Karyotype Activity tab here
The diagram below shows the karyotype for a normal human. Karyotypes are prepared from the nuclei of
cultured white blood cells frozen at the metaphase stage of mitosis. A photograph of the chromosomes is
then cut up and the chromosomes are rearranged on a grid so that the homologous pairs are placed
together. Homologous pairs are identified by their general shape, length, and the pattern of banding produced
by a special staining technique. Karyotypes for a human male and female are shown below. The male
karyotype has 44 autosomes, a single X chromosome, and a Y chromosome (written as 44 + XY), whereas the
female karyotype shows two X chromosomes (written as 44+XX).
Typical Layout of a Human Karyotype
Karyotypes for different species
The term karyotype refers to the chromosome
complement of a cell or a whole organism. In
particular, it shows the number, size, & shape of
the chromosome as seen during metaphase of
mitosis. The diagram on the left depicts the
human karyotype. Chromosome numbers vary
considerably among organisms and may differ
markedly between even closely related species:
Organism
Chromosome #
Human
46
Chimpanzee
48
(Vertebrates)
(Diploid; 2n)
Gorilla
48
Horse
64
Cattle
60
Dog
78
Cat
38
Rabbit
44
Goldfish
94
Rat
42
Distinguishing characteristics of Chromosomes
Each chromosome has distinctive features that enable it to be identified and distinguished from others. The
banding pattern does not represent individual genes, but regions of the chromosome that would contain up to
many hundreds of genes. They are “stained” in a special technique that gives them their banded appearance.
Chromosome Length
Centromere Position
Banding Pattern
Satellite Endings
Karyotype Activity
Determine the sex and chromosome condition of the individual whose chromosomes are displayed on the next
page. The example karyotype presented on the instruction page along with the hints on how to recognize
chromosome pairs can be used to help you complete this activity.
Questions:
1. Explain what a karyotype is and comment on the information it provides:
2. Distinguish between autosomes & sex chromosomes:
3. Determine the sex of this individual:
4. Is the individual’s karyotype normal or abnormal.
5. Explain why the karyotype is either normal or abnormal. (How do you know?)
Analysis:
Cut out the chromosomes, pair them up, & glue them down