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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.
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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
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 – this is called nondisjunction
Nondisjunction Notice the gametes have an uneven distribution of chromatids
Trisomy 21 • Abnormality shown in karyotype • Note that there are three copies of #21 chromosome. • This person has Down Syndrome.
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