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Chapter 7

Chapter 7. Non- Mendelian Genetics. 4 Types of Non - Mendelian Genetics. Incomplete Dominance Codominance Multiple Alleles Sex-linked Inheritance. Incomplete Dominance. Traits are inherited with no definite dominance of either allele. Phenotypes combine to create a separate trait.

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Chapter 7

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  1. Chapter 7 Non-Mendelian Genetics

  2. 4 Types of Non-Mendelian Genetics Incomplete Dominance Codominance Multiple Alleles Sex-linked Inheritance

  3. Incomplete Dominance • Traits are inherited with no definite dominance of either allele. • Phenotypes combine to create a separate trait. • Example, red and white snapdragons offspring pink snapdragons

  4. Punnett Square of Incomplete Dominance Cross • Expressed as R and r alleles as a Punnett Square Cross. • RR (red) X rr (white)

  5. Codominance • Expression of both alleles equally • Phenotype of both traits are seen in heterozygous individuals • Example black rooster and white chicken produce offspring with black and white feathers.

  6. Punnett Square of CodominantCross • Expressed as two separate traits in a Punnett Square Cross • BB (black) X WW (white)

  7. Multiple Alleles • More than two alleles of a certain trait are present • Example ABO blood types • IA and IB and i alleles determine blood types in Punnett Square.

  8. Punnett Square of Multiple Alleles Cross IA i X IB i Both parents are heterozygous for blood type

  9. Sex-linked trait • Gene on the X or Y chromosome • Males only have one copy of X, Females have two copies. • Females can be heterozygous for the trait. • Example Red-Green colorblindness

  10. Inheritance pattern for red-green colorblindness XX (heterozygous carrier) XY (normal color sight)

  11. Inheritance pattern for red-green colorblindness XX (heterozygous carrier) XY (colorblind male)

  12. What is a Pedigree Chart? • A pedigree is a chart of the genetic history of family over several generations. • Scientists or a genetic counselor would find out about your family history and make this chart to analyze.

  13. What does a pedigree chart look like?

  14. Notation on the Pedigree • A circle represents a female. • A square represents a male. • A completely shaded square or circle indicates the person has the trait. • A not shaded shape indicates that a person neither has the trait nor is a carrier. • A half-shaded shape indicates that a person is a carrier.

  15. Most common signs and symbols used in pedigree analysis

  16. Interpreting a Pedigree Chart • Determine if the pedigree chart shows an autosomal or X-linked disease. • If most of the males in the pedigree are affected the disorder is X-linked • If it is a 50/50 ratio between men and women the disorder is autosomal.

  17. Example of Pedigree Charts • Is it Autosomal or X-linked? Autosomal

  18. Interpreting a Pedigree Chart • Determine whether the disorder is dominant or recessive. • If the disorder is dominant, one of the parents must have the disorder. • If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous.

  19. Example of Pedigree Charts • Dominant or Recessive? • Dominant

  20. Example of Pedigree Charts • Dominant or Recessive? • Recessive

  21. Summary • Pedigrees are family trees that explain your genetic history. • Pedigrees are used to find out the probability of a child having a disorder in a particular family. • To begin to interpret a pedigree, determine if the disease or condition is autosomal or X-linked and dominant or recessive.

  22. Queen Victoria’s Family and Hemophilia

  23. karyotype • picture of the chromosomes in a cell used to check for abnormalities

  24. A Human Karyotype has photos of all the matched pairs of human chromosomes from one cell, stained to show banding patterns, and arranged from long to short, with centromeres near the top.Here are our numbers 6-9…

  25. Kleinfelter syndrome

  26. Turner syndrome

  27. Mutations • A mutation is any change in the DNA sequence. • Gene mutations or chromosomal mutations • Mutations in gametes may be passed on to offspring • Mutations in somatic cells cannot be passed to offspring

  28. Types of Gene Mutations • Point mutation a change in a single base pair in the DNA. THE DOG BIT THE CAT THE DOG BIT THE CAR

  29. Types of Gene Mutations • Frameshiftmutation a single base pair is added or deleted, causing a shift in how the DNA strand will be read. THE DOG BIT THE CAT THE DOB ITT HEC AT

  30. Chromosome Mutations • Deletion-part of a chromosome is left out. • Insertion-part of a chromatid breaks off & attaches to its sister chromatid.

  31. Chromosome Mutations • Inversion-part of a chromosome breaks off & reinserts backwards. • Translocation-part of one chromosome breaks off & is added to a different chromosome.

  32. What causes mutations? • spontaneous mistakes • environment Mutagen - any agent that can cause a change in DNA is called a. (x-rays, UV light, asbestos)

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