CancerQuest >> Cell Division >> The Cell Cycle

Chromosome Pairs in Human Cells

The image below shows the chromosomes from a human cell. The depiction of all of the chromosomes in this manner is known as a karyotype. Karyotypes are often performed on fetal tissues during pregnancy to detect chromosomal abnormalities in the unborn child. These chromosomes have been colored by the binding of fluorescent dyes. Notice that there are two copies of each chromosome. The wide range in sizes of the chromosomes is also apparent. The chromosomes are numbered in the inverse order of their size. Chromosome 1 is the largest chromosome and the smallest chromosomes are those numbered 21 and 22. The karyotype shown below is from a male and contains one X and one (much smaller) Y chromosome. The DNA in even the smallest of the chromosomes contains millions of basepairs.

In many cancer cells the number of chromosomes is disturbed so that there are either too many or too few chromosomes in the cells. Cells with too many or too few chromosomes are said to be aneuploid. More on genetic changes and cancer.

The image above is courtesy of Applied Imaging, Santa Clara, CA.