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Genetics

Genetics . the study of heredity. Gregor _______. “Father of Genetics” studied __________ because 1) seeds were readily available 2) they could be cultivated very quickly. Mendel’s Experiment. Trait. a _______ is a specific characteristic of an individual

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Genetics

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  1. Genetics the study of heredity

  2. Gregor _______ • “Father of Genetics” • studied __________ because 1) seeds were readily available 2) they could be cultivated very quickly

  3. Mendel’s Experiment

  4. Trait • a _______is a specific characteristic of an individual • determined by the _______ carried on the chromosomes examples: flowers = color, height humans = hair color, eye color

  5. Traits

  6. Mendel’s 3 Laws • _________________ 2) __________________ 3) ______________________________

  7. Law of Dominance - Dominant allele prevents the recessive allele to be expressed • ______________ = is always expressed; represented by a capital letter • ______________ = is expressed only when dominant allele is not present; represented by a lowercase letter - Example: Human eye color Brown eye is dominant “B” Blue eye is recessive “b”

  8. Law of Segregation Alleles separate during meiosis. As homologous chromosomes separate during meiosis I, alleles on those chromosomes separate. Meiosis I

  9. Law of Independent Assortment - The expression of one trait does NOT affect the expression of another trait because genes separate independently during _________ (if they are on ________ chromosomes). - Example: hair color and eye color are traits that are independently inherited

  10. Law of Independent Assortment - The expression of one trait does not affect the expression of another trait because genes separate independently during meiosis • The genes on ____________chromosomes are assorted independently. • If the genes are on ________chromosome, they are NOT independently assorted.

  11. B = brown eyes b = blue eyes H = brown hair h = blonde hair D = dimples d = no dimples F = large feet f = small feet Meiosis

  12. Exceptions to Mendel’s Laws

  13. True or False • When a black horse mates with a white horse and the offspring is grey, this inheritance is called codominance. • Blood type is both codominance and multiple alleles. • Hair color and height are polygenic inheritance. • When a black chicken mates with a white chicken and the offspring is checkered, this inheritance is called incomplete dominance.

  14. 1) ____________________ Dominant allele is not expressed • completely in __________ genotype Ex: In flowers, R= red, r=white if RR x rr RR = red, rr = white Rr = pink (in between) • Calculate the genotype and phenotype ratios of the offspring for the above

  15. 2) _________________ Both dominant and recessive alleles are expressed • Ex: There are four blood types in human: A, B, AB, and O. • - Alleles __ and __are dominant to __. • - Blood type __ carries both alleles A and B and shows _____________.

  16. 3) ______________ A gene carries more than 2 alleles Ex: Blood types (again!!) - alleles A, B, O are carried on “I” gene • - A, B = dominant; o = recessive • Possible genotypes Type A = IAIA or IAI0 Type B = IBIB or IBI0 Type AB = IAIB Type O = I0I0

  17. Blood Type

  18. Sample blood type problem • Ex: A heterozygous Type A man marries a Type O woman. What will be the possible genotypes and phenotypes of their kids?

  19. ___________________ • A trait controlled by many genes • A gradient of traits or a wide range of traits Ex. Height, skin color, hair color

  20. True or False • When a black horse mates with a white horse and the offspring is grey, this inheritance is called codominance. • Blood type is both codominance and multiple alleles. • Hair color and height are polygenic inheritance. • When a black chicken mates with a white chicken and the offspring is checkered, this inheritance is called incomplete dominance.

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