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A Chromosome Study. Please pick up 1 set of chromosomes marked “normal” and 1 set of abnormal chromosomes labeled A B C or D, in addition to the lab handout If you have scissors, begin cutting out the “normal” chromosomes. If not, begin reading the lab handout. Genetic Screening.
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A Chromosome Study Please pick up 1 set of chromosomes marked “normal” and 1 set of abnormal chromosomes labeled A B C or D, in addition to the lab handout If you have scissors, begin cutting out the “normal” chromosomes. If not, begin reading the lab handout
Genetic Screening • Developing fetuses can be tested for some severe genetic disorders by the process of karyotyping – which analyzes the chromosomes found in each cell. • In this activity you will perform a karyotype on a “normal” set of chromosomes as well as an “abnormal” one.
Karotype: the most accurate test for Down’s Syndrome and other disorders. • A karyotype is a picture of all of the chromosomes found in the cells of an organism • Chromosomes are stained, photographed, and then arranged from largest to smallest
Normal Karyotype • Humans almost always have 23 pairs of homologous chromosomes. • Is this karyotype of a male or female?
Abnormal Karyotype • Some serious genetic disorders are caused by trisomy – a certain kind of mutation that gives an individual 3 copies of a chromosome. • The karyotype below shows trisomy-21, better known as Down’s Syndrome.
Your Karyotypes • You will be constructing 2 karyotypes. • The first will be a normal male or female, (46 XY or 46 XX) • The second will have a trisomy disorder. • This is a lab activity!
What to do • Cut out all of the chromosomes in the normal set. • Pair up homologous chromosomes – they are identical in size and banding pattern • Separate the sex chromosomes from the autosomes. • Arrange the pairs of autosomes from largest to smallest. • Label 1 side of the Human Karyotype Form as “normal.” Glue X chromosomes over the line marked X, Y chromosomes over the line marked Y. • Glue the largest pair over the line numbered 1. Glue the next largest over the line numbered 2. Continue until the smallest pair is glued over number 22. • Repeat the procedure for the abnormal set. There will be one extra chromosome in this set – but which number is it?