1. Patterns of Chromosome Inheritance
Chapter 24

2. Karyotyping Karyotype Chromosomal aberration
Size-ordered chart of the metaphase chromosomes of an individual cell
Chromosomal aberration
A mutation that is large enough to see under a light microscope

3. Amniocentesis

4. Chorionic villi sampling

5. Normal male karyotype

6. Down syndrome karyotype

7. Changes in Chromosome Number
Nondisjunction
Result after fertilization:
Trisomy
Monosomy

8. Nondisjunction in Meiosis I

9. Nondisjunction in Meiosis II

10. Down Syndrome

11. Changes in Sex Chromosome Number
Y chromosome-determines maleness.
SRY gene produces a testis-determining factor
Caused by non-disjunction

12. Non-disjunction in Sex Chromosomes
Y chromosome-determines maleness.
Results of non-disjunction?:
XXX
XXY
XYY X0 0Y
Survivable with problems
Survivable with problems
Survivable with problems
Survivable with problems
Lethal

13. Non-disjunction in Sex Chromosomes
Turner Syndrome --XO
Klinefelter Syndrome—XXY
Poly-X Females---XXX
Jacobs Syndrome---XYY

14. Changes in Chromosome Structure
Mutation– a permanent genetic change.
Chromosome mutation--change in chromosome structure.
Types:
Inversion
Translocation
Deletion
Duplication

15. Deletion

16. Duplication

17. Translocation

18. Inversion

19. WHAT’S HAPPENING??

20. Sex-Linked Traits
Traits controlled by genes on the X or Y chromosomes are sex-linked although most are unrelated to gender.
An allele on the X chromosome that is in the region where the Y chromosome has no alleles will express even if recessive; it is termed X-linked.
A female would have to have two recessive genes to express the trait; a male would only need one.

21. X-Linked Alleles
The key for an X-linked problem shows the allele attached to the X as in:
XB = normal vision
Xb = color blindness.
Females with the genotype XBXb are carriers because they appear to be normal but each son has a 50% chance of being color blind depending on which allele the son receives.
XbXb and XbY are both colorblind.

22. Cross involving an X-linked allele

23. X-linked recessive pedigree chart

24. X-Linked Disorders Red-green color blindness Muscular dystrophy.
Hemophilia.

25. http://perth. uwlax. edu/faculty/howard/BIO101/DNA&translation/sld002

26. Diana

27. Chapter Summary
Humans - 22 pairs of autosomes and one pair of sex chromosomes
Abnormalities of chromosome number or composition.
Males - XY
Females -XX.
Chromosomal mutations
Sex-linked traits