1. Sex Determination & Nondisjunction Disorders June 13, 2016

2. Karyotype Human Karyotype:  46 chromosomes organized in 23 pairs in order of decreasing size Pairs # 1-22:  autosomes  somatic (body) chromosomes  all 22 pairs are homologous Pair # 23:  sex chromosomes  contain genes that code for sexual characteristics

3. June 13, 2016 Karyotype

4. June 13, 2016 Female Karyotype  XX  homologous pair  2 sets of genes for every trait Sex Chromosomes

5. June 13, 2016 Sex Chromosomes XYXY  not homologous (no pair)  each one contains different genes  males only have 1 copy of genes on X & Y chromosome Male Karyotype

6. June 13, 2016 Sex Determination X X X Y Who determines the gender of offspring in humans?  all eggs carry one X chromosome  ½ of sperm carry one X chromosomes  ½ of sperm carry one Y chromosomes  Therefore: male determines the gender meiosis XX XYXY XX XY eggssperm

7. June 13, 2016 Nondisjunction Disorders anaphase I

8. June 13, 2016 Nondisjunction Disorders Nondisjunction:  one pair of homologous chromosome doesn’t separate during anaphase I  Result:  ½ gametes have one chromosome too few  other ½ gametes have one chromosome too many  in females, nondisjunction occurs more often if >35 years old missing one chromosome one extra chromosome

9. June 13, 2016 Nondisjunction Disorders amniocentesis :  recommended for all women over 35 years old  fetal cells removed with a needle from amniotic fluid  karyotype of fetal cells examined for nondisjunction disorders http://pregnancy.healthguru.com/content/ video/watch/100062/Understanding_Amni ocentesis?HG_Google_Video_Sitemap=

10. June 13, 2016 Chromosomal Abnormalities  occur when a normal gamete (n = ___)joins with a gamete that has: 1.n + 1:  individual will have ______________________ 2.n - 1:  individual will have ______________________  in either case the resulting individual will suffer from some disabilities depending on which chromosomes are involved (24) (1 chromosome too many)47 45 (1 chromosome less) (22) 23

11. June 13, 2016 Nondisjunction Disorders Common Examples: 1.Down Syndrome trisomy 21 2.Klinefelter’s syndrome XXY 3.Turner’s syndrome X0 monosomy 4.Trisomic female (super female) XXX 5.Jacob’s syndrome (super male) XYY male female (47) (45)

12. June 13, 2016 Chromosomal Abnormalities Down Syndrome  trisomy 21

13. June 13, 2016 Chromosomal Abnormalities Down Syndrome  developmental delays  physical abnormalities  short  folds around eyes  short fingers & toes  large protruding tongue  weak muscles  heart defects

14. June 13, 2016 Chromosomal Abnormalities Klinefelter’s syndrome ● XXY ● male

15. June 13, 2016 Chromosomal Abnormalities Klinefelter’s syndrome ● tall ● small testicles ● after puberty develop some feminine traits (ex. breasts) ● sterile

16. June 13, 2016 Chromosomal Abnormalities Turner’s syndrome ● XO ● female

17. June 13, 2016 Chromosomal Abnormalities Turner’s syndrome ● short ● thick neck ● never goes through puberty ● sterile 15 year old

18. June 13, 2016 Chromosomal Abnormalities Trisomic Female ● XXX ● super female ● have very few problems ● most are fertile

19. June 13, 2016 Chromosomal Abnormalities Jacob’s syndrome ● XYY ● super male ● very tall ● low mental ability ● often aggressive

20. June 13, 2016 Homework Page 120 #1-5 Karyotype Assignment