Chromosomal Mutations and Nondisjunctions

1. Chromosomal Mutations and Nondisjunctions Mistakes of Meiosis

2. ________________ Abnormalities CHROMOSOMAL • 1 infant in 200 newborns has a chromosomal abnormality • 28% of first trimester miscarriages have a chromosomal abnormality • Abnormalities in larger chromosomes don’t usually survive

3. Chromosomal Mutations Change in the structure of a chromosome due to the deletion, replication, or changing position, of a gene or set of genes Deletion Replication Inversion Translocation

4. Homologous chromosomes ___________________ during MEIOSIS NONDISJUNCTION fail to separate One cell gets 2 copies (an extra) chromosome the other is missing a chromosome .

5. Normal Meiosis Nondisjunction http://web.udl.es/usuaris/e4650869/docencia/gen_etica/meioferti2.html http://www.tokyo-med.ac.jp/genet/anm/domov.gif

6. How Does Nondisjunction Affect Fertilization? Since it happens to a sperm or egg, the new baby can end up with _____________ of a chromosome = __________________ OR only ___________ of a chromosome = ___________________ 3 copies TRISOMY one copy MONOSOMY

7. Body cells have 2 of each chromosomeexcept one pair has 3 copies = Trisomy (2n+1) How many chromosomes? 47

8. Body cells have 2 of each chromosomeexcept one pair = Monosomy (2n-1) How many chromosomes? 45

9. How are Abnormalities Detected? A __________ is a picture of an organism’s chromosomes KARYOTYPE (need cells from baby)

10. What Does a Karyotype Show You? Can tell __________________ chromosomes and also the ______________________ of a sequence of genes Can’t see _______________ mutations MISSING/EXTRA GENDER DELETIONS/INSERTIONS single gene

11. How is Gender Determined? Chromosomes that determine the sex of an organism = _________________ All other chromosomes = _________________ Sex chromosomes autosomes y X Humans have two sex chromosomes and _____ autosomes 44

12. SEX DETERMINATION XX = female male Xy =

13. Which of these is a Male?

14. Who determines the gender? Mom can give X Dad can give X or y X X X X X X X y X y X y If dad gives X with mom’s X = girl If dad give y with mom’s X = boy

15. Human Abnormalities caused by Non-Disjunction______________________________________________________ Down syndrome Klinefelter syndrome Turner syndrome

16. Down syndrome (Trisomy 21) 1 in 800 births Similar facial features Slanted eyes Protruding tongue

17. Down syndrome (Trisomy 21) Simian line on palm

18. Down syndrome (= ___________) TRISOMY 21

19. Nondisjunction of Autosomal Chromosomes Male with trisomy 21 (Downs syndrome)

20. Down syndrome (Trisomy 21) Most common chromosomal abnormality 50% have heart defects that need surgery to repair Mild to severe mental retardation Increases susceptibility to many diseases Risk of having a child with Down syndrome increases with age of mom

21. Sex Chromosomal Nondisjunction • Failure of chromosomes to separate properly during meiosis • Can lead to cells with extra genetic material (chromosomes) • Can lead to cells without any chromosomes (bar bodies)

22. 1. What would be the gender make-up of a zygote if a sperm with two XX chromosomes fertilized a normal egg? 2. What would be the gender make-up of a zygote if a sperm with an X and a Y chromosomes fertilized a normal egg? 3. What would be the gender make-up of a zygote if a sperm without a gender chromosome fertilized a normal egg?

23. Turner syndrome

24. Turner syndrome ____ 1 in 5000 births Females have only one X chromosome Small size Slightly decreased intelligence 35% have heart abnormalities Hearing loss common Broad chest Reproductive organs don’t develop at puberty Can’t have children XO http://medgen.genetics.utah.edu/photographs/diseases/high/611.gif

25. Klinefelter syndrome XXy

26. Klinefelter syndrome 1 in 1000 births Males have extra X chromosomes (Can be XXy, XXXy, or XXXXy) Average to slight decrease in intelligence Small testes/can’t have children Usually not discovered until puberty when don’t mature like peers