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What are they?? How do we use them? 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

Is this a normal karyotype?? 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 B C D A B C D

Problems with chromosomes Deletion: missing parts of chromosome A B C D A D

Problems with chromosomes Inversion: parts of chromosome tched A B C D A C B 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 Recessive: requires 2 allele copies to express disorder Dominant: requires only 1 allele copy to express disorder

Recessive disorders

Dominant disorder