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Warm Up Complete Edpuzzle on pedigrees If you haven’t completed Edpuzzle from yesterday do so now You will have 10 minutes before we start the notes Karyotypes What are they?? How do we use them? Normal Karyotype--male Normal Karyotype--female Is this person female or male? How are DNA samples obtained for karyotypes? What to look for? Are there 46 chromosomes? Are there 2 identical pairs of each autosome and 2 sex chromosomes? Are there any rearrangements between chromosomes or large deletions? Trisomy 21 or Down Syndrome 1 in 700 births 47 chromosomes XY or XX #21 Trisomy Nondisjunction 3 Correlation between mother’s age and Trisomy 21 incidence Turners syndrome caused by Nondisjunction Monosomy Male or Female? Is this a normal karyotype?? XXY Male (Extra X) Klinefelter syndrome XXY on 23rd pair Male with some female characteristics small testes that do not produce as much testosterone as usual Delayed puberty Reduced body hair infertility Deletion—18 Q Deletion Syndrome 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. Nondisjunction What we can’t see Individual DNA strands or genes The number of genes in any given area of a chromosome. The presence or location of small mutations. (Scientists cannot predict diseases caused by small mutations within genes. Other chromosomal disorders that can arise? Problems with chromosomes Duplication: copied parts of chromosome A A B B C B D B C D Problems with chromosomes Deletion: missing parts of chromosome A A B D C D Problems with chromosomes Inversion: parts of chromosome tched A A B C C B D D Chromosomal mutations Deletion Duplication Inversion Translocation Human genetic disorders from deleterious genes Sometimes the alleles inherited contribute to disorders and not from the number or shape of the chromosomes. Sex-linked: genes found on X or Y chromosome 2. Recessive: requires 2 allele copies to express disorder 3. Dominant: requires only 1 allele copy to express disorder 1. Recessive disorders Dominant disorder
