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Patterns of Chromosome Inheritance

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Presentation on theme: "Patterns of Chromosome Inheritance"— Presentation transcript:

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


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.

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

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