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Human Heredity

Human Heredity. Chapter 14. Human Chromosomes. Chromosomes are only visible during cell division (mitosis/meiosis). To analyze chromosomes, biologist photograph cells during mitosis and align the chromosomes in homologous pairs. This picture is known as a karyotype. Types of Chromosomes.

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Human Heredity

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  1. Human Heredity Chapter 14

  2. Human Chromosomes • Chromosomes are only visible during cell division (mitosis/meiosis). • To analyze chromosomes, biologist photograph cells during mitosis and align the chromosomes in homologous pairs. • This picture is known as a karyotype

  3. Types of Chromosomes • On a human karyotype: • Chromosome pairs 1-22 are known as autosomes. • They code for traits that are not related to sex. • Both males and females have the same type • Chromosome pair 23 includes the sex chromosomes. • Males have XY and females have XX.

  4. CHROMOSOMAL MUTATIONS ____________________________: Change in the ______________ or ____________ of chromosomes structure number

  5. fail to separate NONDISJUNCTION Homologous chromosomes ________________ during MEIOSIS = _________________________ One cell gets 2 copies of the chromosome the other cell gets none.

  6. Down syndrome (= ____________) TRISOMY 21

  7. Down syndrome (Trisomy 21) • Most common chromosomal abnormality • Mild to severe mental retardation • Risk of having a child with Down syndrome increases with age of mom

  8. Did you know??? • Sex is determined by the father of a child. • You have a 50% chance of having a boy or a girl ?

  9. X X Who decides? X X X X X Mom can give X Dad can give X or y X y X y y Dad SO ____ determines sex of the baby. If dad gives X with mom’s X = girl If dad give y with mom’s X = boy

  10. Sex Linked Genetic Disorders

  11. SEX CHROMOSOMES CAN CARRY OTHER GENES TOO= ___________________ SEX LINKED TRAITS These traits show up in different _______________ in males and females because they move with the sex chromosomes percentages

  12. carried on Y Y-LINKED GENES: Genes ______________ chromosome EXAMPLE:Hairy pinna Y linked _________genes _____ show up in males ONLY

  13. X-LINKED ____________ GENES: are carried on the X chromosome X-linked recessive disorders show up _____________ in ______ than females because males only have ______ X chromosome. MORE frequently MALES ONE

  14. HEMOPHILIA Blood clotting proteins on X CAUSE: Mutation in genes for __________________ carried ______ chromosome Blood clotting proteins are missing so person with this disorder can’t stop bleeding when injured; can ________________ from minor cuts or suffer internal bleeding from bruises or bumps. bleed to death

  15. Muscular Dystrophy CAUSE: deletion in gene that codes for a _______________ Results in ____________________ and loss of ___________________ muscle protein weakening skeletal muscle http://www.cadenhead.org/workbench/gems/jerry-lewis-telethon.jpg http://www.tokyo-med.ac.jp/genet/chm/dei.gif

  16. COLORBLINDNESS Color vision CAUSE: Mutation in one of three genes for _______________ carried on X chromosome Persons with this disorder have trouble distinguishing colors. Seen in 1 in 10 males 1 in 100 females http://gizmodo.com/gadgets/peripherals/samsung-develops-lcd-for-colorblind-036306.php

  17. When Harry Met Sally… • Harry and Sally are two normal vision adults who have a color blind son. • B – normal vision b – color blind • Show the cross between Harry and Sally. • What are the genotypes of Harry and Sally? • XBY, XBXb http://www1.istockphoto.com/file_thumbview_approve/2341727/2/istockphoto_2341727_cute_cartoon_couple_drinking_vector.jpg

  18. Harry and Sally Continued • Give all of the possible genotypes and phenotypes of their offspring. • XBXB – normal vision daughter • XBXb – normal vision daughter (carrier) • XBY – normal vision son • XbY – color blind son • Sally’s dad has normal vision. Is Sally’s Mom colorblind? • She could be colorblind, or she could be a carrier for the colorblindness trait.

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