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KEY CONCEPT Phenotype is affected by many different factors.

KEY CONCEPT Phenotype is affected by many different factors. In (3.)incomplete dominance , (AKA- intermediate dominance) neither allele is completely dominant nor completely recessive. Heterozygous phenotype is intermediate between the two homozygous phenotypes

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KEY CONCEPT Phenotype is affected by many different factors.

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  1. KEY CONCEPT Phenotype is affected by many different factors.

  2. In (3.)incomplete dominance, (AKA- intermediate dominance) neither allele is completely dominant nor completely recessive. • Heterozygous phenotype is intermediate between the two homozygous phenotypes • Use capital letters and apostrophes’ • RR-red homozygous dominant • RR’-pink heterozygote is intermediate • R’R’-white homozygous recessive

  3. Phenotype can depend on interactions of alleles. • In (3.)incomplete dominance, neither allele is completely dominant nor completely recessive. • Heterozygous phenotype is intermediate between the two homozygous phenotypes • Homozygous parental phenotypes not seen in F1 offspring • B1B1 GreenB2B2 blueB1B2 royal blue

  4. Codominant alleles are neither dominant nor recessive. • Ex. The ABO blood types result from codominant alleles. • Ex. Sickle cell disorder • RR- normal red blood cell shape • RS-sickle cell trait- carrier • SS-sickle cell anemia • (4)Codominant –equal expression of both alleles.

  5. Genetic disorder- • Hemoglobin- a protein in Red Blood Cells that carry oxygen to body cells • Sickle cell anemia-a genetic disorder that causes a change in the shape of red blood cells • Sickle cell Trait-some normal, some sickle shaped cells

  6. (5) multiple alleles • Traits that are controlled by more than 2 alleles, although only two alleles exist in a diploid cell. • Example- Human Blood Types-each person inherits two alleles, one from each parent, but three exist in the human “gene pool”. 4 blood types3 alleles • Type-A IAIA, IAi A is dom. to O • Type-B IBIB, IBi B is dom. To O • Type-AB IAIB AB are codominant • Type-O ii recessive • This is determined by the shape of proteins on red blood cells and by the presence or absence of plasma antigens. O universal donor-AB universal receiver.

  7. Order of dominance: brown > green > blue. (6)Polygenic -many genes may interact to produce one trait. The genes may be on the same or on a different chromosome.Result in a wide rangeof variation.Ex. Hair color, height eye color

  8. Often compared to a bell curve • AA,BB,CC highest range • aa.bb.cc lowest range • Aa,Bb,Cc middle

  9. An (7)epistatic gene can interfere with other genes.

  10. Other factors of gene expression Phenotype is a combination of genotype and environment. • External environment- • temperature, nutrition, • light • Internal factors: different • hormones, structures, and • effects of aging. Ex.The sex of sea turtles depends on both genes and the environment-(temperature of the nest) • Ex.Height is an example of a phenotype strongly affected by the environment.

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