Loading…

Flash Player 9 (or above) is needed to view presentations.
We have detected that you do not have it on your computer. To install it, go here.

Like this presentation? Why not share!

Like this? Share it with your network

Share

Chapter 15

on

  • 1,572 views

 

Statistics

Views

Total Views
1,572
Views on SlideShare
1,571
Embed Views
1

Actions

Likes
0
Downloads
47
Comments
0

1 Embed 1

https://www.facebook.com 1

Accessibility

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Chapter 15 Presentation Transcript

  • 1. Chapter 15 notes The Chromosomal Basis of Inheritance
  • 2. Concept 15.1
    • In 1902 Sutton noted the parallels between the behavior of chromosomes and the behavior of Mendel’s factors.
    • Chromosomal theory of inheritance : genes have specific loci on chromosomes, and the chromosomes undergo segregation and independent assortment
  • 3. Concept 15.1
  • 4. Concept 15.1
    • Morgan traced a gene to a specific chromosome
    • - Morgan used Drosophila “fruit flies” for his experiments
    • - only 4 pairs of chromosomes
    • - wild type flies have red eyes
    • - white eyes is a mutant phenotype
  • 5. Concept 15.1
    • - Morgan mated the white-eyed male to a red-eyed female
    • - all F 1 offspring were red-eyed
    • - The F 2 offspring were not 3:1; instead all females were red-eyed while half of the males had red and half had white eyes
    • - eye color was linked to the fly’s sex
  • 6. Concept 15.1
    • Genes located on sex chromosomes are called sex-linked genes
    • - Morgan’s evidence that a specific gene is carried on the X chromosome helped confirm the chromosomal theory of inheritance.
  • 7. Concept 15.1
  • 8. Concept 15.2
    • linked genes : genes that are located on the same chromosomes and tend to be inherited together
    • - linked genes deviate from expected Mendelian ratios
    • -ex. in flies body color and wing shape are inherited together
  • 9. Concept 15.2
  • 10. Concept 15.2
    • Genetic recombination : the production of new combinations of traits inherited from two parents
    • yellow-round x green-wrinkled
    • YyRr x yyrr
    • Parental types : when the offspring phenotypes are identical to the parents
    • - ex ¼ YyRr, ¼ yyrr
  • 11. Concept 15.2
    • Recombinants : when the offspring phenotypes are new combinations
    • ex ¼ Yyrr, ¼ yyRr
    • When 50% of all offspring are recombinants, we say there is a 50% frequency of recombination
    • - 50% frequency is observed for genes located on different chromosomes
  • 12. Concept 15.2
    • Geneticists can use recombination data to map a chromosomes genetic loci
    • Genetic map : an ordered list of the genetic loci along a particular chromosome
    • Linkage map : a genetic map based on recombination frequencies
  • 13. Concept 15.2
    • Map of body-color ( b ), wing-size ( vg ) and cinnabar ( cn )
    • - cn and b is 9%
    • - cn and vg is 9.5%
    • - b and vg is 17%
  • 14. Concept 15.2
  • 15. Concept 15.3
    • Sex-linked genes have unique patterns of inheritance
    • - fathers pass sex-linked alleles to daughters, but not sons
    • - mothers pass sex-linked alleles to both sons and daughters
  • 16. Concept 15.3
    • Because males only have one locus, they cannot be heterozygous
    • Sex-linked disorders in humans
    • - muscular dystrophy : 1/3500 males in the US
    • - hemophilia : absence of proteins for blood clotting
  • 17. Concept 15.3
  • 18. Concept 15.4
    • Nondisjunction : the members of a pair of homologous chromosomes do not move apart properly during meiosis I or II.
    • - gametes are (n+1) or (n-1) if they have too many or too few chromosomes
  • 19. Concept 15.4
    • Aneuploidy : having an abnormal chromosome number
    • Trisomic : a chromosome in triplicate (2n+1); ex. trisomy 21 (Down’s syndrome)
    • Monosomic : if a chromosome is missing (2n-1)
  • 20. Concept 15.4
  • 21. Concept 15.4
    • Polyploidy : organisms that have more than two complete chromosome sets
    • - triploidy (3n)
    • - tetraploidy (4n)
    • Polyploids are more normal in appearance than aneuploids
  • 22. Concept 15.4
  • 23. Concept 15.4
    • Breakage of a chromosome can lead to four types of changes in chromosome structure
    • Deletion : occurs when a chromosomal fragment lacking a centromere is lost during cell division
  • 24. Concept 15.4
    • Duplication : a fragment becomes attached as an extra segment to a sister chromatid
    • Inversion : a chromosomal fragment can reattach to the original chromosome in reverse order
    • Translocation : the fragment joins a nonhomologous chromosome
  • 25. Concept 15.4
  • 26. Concept 15.4
    • Alterations in chromosome number and structure are associated with several human disorders
    • - Down syndrome : 1/700 children born; extra 21 st chromosome
    • - Klinefelter syndrome: XXY male
    • - Turner syndrome: XO female
  • 27. Concept 15.4
  • 28. Concept 15.4
  • 29. Concept 15.4