1 / 13

LEQ: How do the events of meiosis account for Mendel ’ s laws?

LEQ: How do the events of meiosis account for Mendel ’ s laws?. 9.18. Chromosome Theory of Inheritance. Genes occupy a specific location on a chromosome Chromosomes undergo segregation and independent assortment.

ewan
Download Presentation

LEQ: How do the events of meiosis account for Mendel ’ s laws?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. LEQ: How do the events of meiosis account for Mendel’s laws? 9.18

  2. Chromosome Theory of Inheritance Genes occupy a specific location on a chromosome Chromosomes undergo segregation and independent assortment

  3. * Segregation occurs when homologous chromosomes are separated during anaphase I.* Independent Assortment occurs when homologous chromosomes line up together during metaphase I.

  4. LEQ: How are linked genes inherited? 9.19 and 9.20

  5. Linked Genes • Genes found on the same chromosome • Linked genes do NOT independently assort • Look and behave like a monohybrid Punnett square

  6. Thomas Hunt Morgan • American embryologist – early 1900’s, studied fruit flies, identified the process of “crossing over” by studying linked genes • Why is Drosophila melanogaster a good organism to study? • Few chromosomes • Small • Easy to care for • Lots of offspring • Quick generation time

  7. How do you get genetic diversity with linked genes? Crossing over occurs. Chromatids with new gene combinations are referred to as recombinant chromatids.

  8. Recombination Frequency The percentage of recombinants from a cross. In this example Morgan observed 17% recombination frequency.

  9. LEQ: How is gender determined? 9.22

  10. Sex Determination Systems • X-Y: humans & fruit flies; XX = female; XY = male; sperm determines sex • X-O: insects (grasshoppers & roaches) O = absence of a sex chromosome; XX = female; X- = male; sperm determines sex by having an X or having no sex chromosome • Z-W: fish, butterflies, & birds; ZZ = male; ZW = female; egg determines sex • Number: ants & bees; females are diploid – fertilized eggs; males are haploid – unfertilized eggs

  11. LEQ: How are some traits linked to our gender? 9.23

  12. Sex Linked Genes • Genes that are located on sex chromosomes • Thomas Hunt Morgan identified sex linked traits by studying eye color in fruit flies • He noticed that white eye color is more common in males than females

  13. Fruit Fly Eye Color

More Related