KEY CONCEPT
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KEY CONCEPT Phenotype is affected by many different factors. PowerPoint PPT Presentation


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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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Key concept phenotype is affected by many different factors

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

    • Use capital letters and apostrophes’

    • RR-red homozygous dominant

    • RR’-pink heterozygote is intermediate

    • R’R’-white homozygous recessive


Phenotype can depend on interactions of alleles

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


Key concept phenotype is affected by many different factors

  • 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.


Key concept phenotype is affected by many different factors

  • 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


5 multiple alleles

(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-AIAIA, IAi A is dom. to O

  • Type-BIBIB, IBiB is dom. To O

  • Type-ABIAIBAB are codominant

  • Type-Oiirecessive

  • 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.


Key concept phenotype is affected by many different factors

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


Often compared to a bell curve

Often compared to a bell curve

  • AA,BB,CChighest range

  • aa.bb.cclowest range

  • Aa,Bb,Ccmiddle


Key concept phenotype is affected by many different factors

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


Other factors of gene expression phenotype is a combination of genotype and environment

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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