Karyotype Notes
What each of the human chromosomes look like
Karyotype: A photomicrograph of chromosomes arranged according to a standard classification
In other words… Chromosomes are digitally arranged so that they are matched with their homologue or “ partner ” chromosome. Homologue chromosomes are the same size, shape, and carry the same genes, and one is inherited from each parent. They are numbered according to size.
Sex determination with karyotype This karyotype has 23 exact pairs, which means the person is female. Note that #23 chromosomes are both X.
Normal human male Note that #23 chromosomes are X and Y. Notice the size of the Y chromosome. It is much smaller then the X
Is this person female or male?
Trisomy 21 Abnormality shown in karyotype Note that there are three copies of #21 chromosome. This person has Down Syndrome.
Correlation between mother’s age and Trisomy 21 incidence
Monosomy X Abnormality shown in karyotype Note this person only has 1 copy of the X chromosome. This female has Turner’s syndrome.
XXY Male (Extra X) Notice that this person has an extra X chromosome. This is called Klinefelters. They would be considered a male even though they 2 X chromosomes
If there are chromosomal number abnormalities, how do they form? Meiosis: the process of creating sperm or egg from a diploid cell If there is a mistake when chromosomes are separating, then the resulting sperm or egg will have too many or too few chromosomes.