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Question…

Question…. A child is born with blue eyes even though BOTH his parents have brown eyes. How is this possible? Can two blue eyed parents have a brown eyed child? Explain why or why not. Genetics:. The study of heredity. Heredity = the passing of traits from parents to offspring.

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  1. Question… A child is born with blue eyes even though BOTH his parents have brown eyes. How is this possible? Can two blue eyed parents have a brown eyed child? Explain why or why not.

  2. Genetics: The study of heredity

  3. Heredity= the passing of traits from parents to offspring

  4. Heredity = the passing of traits from parents to offspring • Trait = A feature or characteristic of a person • Physical appearance • Behavior tendencies • Predisposed to medical conditions • A person’s traits are influenced by: • their genetic inheritance • environmental factors What is a trait?

  5. Trait = a feature or characteristic of a person • Physical appearance • Genetics: • Environment: hair color eye color face shape hair texture smile shape

  6. Trait = a feature or characteristic of a person • Physical appearance • Genetics: genes determine natural hair color • Environment: hair color eye color face shape hair texture smile shape

  7. Trait = a feature or characteristic of a person • Physical appearance • Genetics: genes determine natural hair color • Environment:sun or hair dyes change hair color hair color eye color face shape hair texture smile shape

  8. Trait = a feature or characteristic of a person • Behavior tendencies • Genetics: • Environment:

  9. Trait = a feature or characteristic of a person • Behavior tendencies • Genetics: genes determine the tendency to use a certain hand • Environment:

  10. Trait = a feature or characteristic of a person • Behavior tendencies • Genetics: genes determine the tendency to use a certain hand • Environment: can learn to use the opposite hand

  11. Trait = a feature or characteristic of a person • Predisposed to medical conditions • Genetics: • Environment:

  12. Trait = a feature or characteristic of a person • Predisposed to medical conditions • Genetics: genes determine a risk of heart disease • Environment:

  13. Trait = a feature or characteristic of a person • Predisposed to medical conditions • Genetics: genes determine a risk of heart disease • Environment: eating healthy foods and exercising can reduce risk

  14. Trait = a feature or characteristic of a person • Phenotype = a person’s version of a trait • “physical appearance” hair color: black eye color: blue hair texture: straight

  15. Practice • List 3 traits Dash has. • List Dash’s phenotype for each trait.

  16. Trait = a feature or characteristic of a person • Gene = part of a person’s DNA that influences a trait Eye color gene Face shape gene Hair color gene

  17. Gene= part of a person’s DNA that controls a trait • Alleles= different versions of a gene Eye color gene: brown allele Eye color gene: blue allele

  18. Practice • List 3 possible alleles for the hair color gene. Hair color gene

  19. Alleles = different versions of a gene • Dominant Allele • Represented by a capital letter • Example: B for brown eyes • Recessive allele • Represented by a lowercase letter • Example:b for blue eyes

  20. Alleles = different versions of a gene • All people have 2 alleles for every gene (one from each parent) Allele of eye color gene from dad Allele of eye color gene from mom

  21. Alleles = different versions of a gene • All people have 2 alleles for every gene (one from each parent) • Genotype = a person’s combination of alleles • “genetic makeup” Allele of eye color gene from dad Allele of eye color gene from mom

  22. Genotype = a person’s combination of alleles • A person may inherit 2 of the same alleles = purebred or Homozygous • 2 dominant alleles = purebred/Homozygous dominant • Example: B and B Genotype = Phenotype = Mom Dad E E Child

  23. Genotype = a person’s combination of alleles • A person may inherit 2 of the same alleles = purebred or Homozygous • 2 dominant alleles = purebred/Homozygousdominant • Example: B and B Genotype = BB Phenotype = Mom Dad E E Child

  24. Genotype = a person’s combination of alleles • A person may inherit 2 of the same alleles = purebred or homozygous • 2 dominant alleles = purebred/homozygous dominant • Example: B and B Genotype = BB Phenotype = brown eyes Mom Dad E E Child

  25. Genotype = a person’s combination of alleles • A person may inherit 2 of the same alleles = purebred • 2 recessive alleles = Mom Dad e e Child

  26. Genotype = a person’s combination of alleles • A person may inherit 2 of the same alleles = purebred • 2 recessive alleles = purebred recessive • Example: b and b Genotype = Phenotype = Mom Dad e e Child

  27. Genotype = a person’s combination of alleles • A person may inherit 2 of the same alleles = purebred or homozygous • 2 recessive alleles = purebred/homozygous recessive • Example: b and b Genotype = bb Phenotype = Mom Dad e e Child

  28. Genotype = a person’s combination of alleles • A person may inherit 2 of the same alleles = purebred or homozygous • 2 recessive alleles = purebred/homozygous recessive • Example: b and b Genotype = bb Phenotype = blue eyes Mom Dad e e Child

  29. Alleles = different versions of a gene • A person may inherit 2 different alleles = hybrid or heterozygous • Dominant allele masks recessive allele • Example: B and b Genotype = Phenotype = Mom Dad Mom Dad e E E e -or- Child Child

  30. Alleles = different versions of a gene • A person may inherit 2 different alleles = hybrid or heterozygous • Dominant allele masks recessive allele • Example: B and b Genotype = Bb Phenotype = Mom Dad Mom Dad e E E e -or- Child Child

  31. Alleles = different versions of a gene • A person may inherit 2 different alleles = hybrid or heterozygous • Dominant allele masks recessive allele • Example: B and b Genotype = Bb Phenotype = brown eyes Mom Dad Mom Dad e E E e -or- Child Child

  32. Practice • Brown hair (B) is dominant to blond hair (b).

  33. Practice • Brown hair (B) is dominant to blond hair (b).

  34. Practice • Brown hair (B) is dominant to blonde hair (b).

  35. Practice • Brown hair (B) is dominant to blond hair (b). Which genotypes are purebred? Which ishybrid?

  36. Practice • Right-handedness (R) is dominant to left-handedness (r). What genotype(s) could a right-handed person have? What genotype(s) could a left-handed person have? RR or Rr rr

  37. Practice • In pea plants, green peas (G) are dominant to yellow peas (g). What would be the genotype of a: -purebred green pea? -hybrid green pea? -yellow pea? GG Gg gg

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