Genetics Brown Eye Gene Blue Eye Gene What
Genetics
Brown Eye Gene Blue Eye Gene
What is an ALLELe? • Different form/version of a gene • You inherited ONE ALLELE from each parent for each trait. • For example – • Gene = eye color • Allele = blue, hazel, brown, and green
Dominant vs. Recessive Alleles • Dominant allele hides the recessive allele. – The Dominant allele always shows/is visible – For example – hair color – brown is dominant to all other hair colors – EX: mom gave you the allele (gene) for brown hair. Dad gave you the allele for blonde hair. You will have what color hair? – Answer: Brown hair
Dominant vs. Recessive Alleles (Cont. ) • Recessive allele is always hidden if a dominant allele is present. • You must inherit 2 recessive alleles for the trait to show up/become visible. – EX: – hair color – blonde is recessive to all other hair colors – mom has to give you the allele (gene) for blonde hair and dad gave you the allele for blonde hair, you will have blonde hair!
Writing Alleles? • All alleles are assigned letters • Dominant allele=CAPITAL letters – B=(Brown eyes) • Recessive allele – lower case – b= (blonde eyes)
• Two letters pair for each trait – one passed on from mom and one from dad • Using the letter B tell me what a person with brown hair would look like – BB_____ – Bb_____ – bb_____ • Is this trait dominant or recessive? – DOMINANT • What if the person had blonde hair (recessive trait)? – bb
How you get your traits? • Dimples are a dominant trait. Non dimples are recessive. If both parents have dimples would all the kids have dimples?
Genotype vs. Phenotype • Phenotype- physical trait – can be seen – Brown or blonde • Genotype- genetic makeup – Alleles inherited – (not seen BB, Bb)
Genotype/Phenotype Practice • Are the following genotype or phenotype • Hazel Eyes. – Phenotype • BB – Genotype • Long Toes – Phenotype • Rr – genotype • Tt – genotype • Ear Hair – Phenotype • Ff – genotype • Freckles – phenotype
Homozygous vs Heterozygous • PREFIXES: – HOMO=SAME alleles for a specific trait ( TT or tt) – HETERO=DIFFERENT alleles for a specific trait (Tt or Bb)
Practice • 1. ) If you inherited the 2 alleles for blue eyes (1 from each parent), your phenotype is _____, your genotype is _____, and you’re _____ zygous. • 2. ) If you inherit the dominant allele for dimples from your dad, and the recessive for no dimples from your mom, your phenotype is ______, your genotype is _______, and you’re ____ zygous.
Practice Problems Will the following plants be tall or short? T=tall and t=short Tt TT tt Are the following plants homozygous or heterozygous? TT Tt tt
Practice What is the phenotype of the following plants? Tt TT tt
• • • Genotype codes for Phenotype. P = Purple and p= white Y = Yellow and y = green R = Round and r = wrinkled Genotype is RR, the Phenotype is ______. Genotype is YY, the Phenotype is ______. Genotype is pp, the Phenotype is ______. Genotype is Rr, the phenotype is ______. Genotype is Yy, the phenotype is ______. Phenotype is wrinkled, the genotype is ____. Phenotype is green, the genotype is _____.
• • • Genotype codes for Phenotype. P = Purple and p= white Y = Yellow and y = green R = Round and r = wrinkled Genotype is RR, the Phenotype is ______. Genotype is YY, the Phenotype is ______. Genotype is pp, the Phenotype is ______. Genotype is Rr, the phenotype is ______. Genotype is Yy, the phenotype is ______. Phenotype is wrinkled, the genotype is ____. Phenotype is green, the genotype is _____.
• • • • • . Write Ho. for homozygous or He. for heterozygous. AA _____ Bb ____ Cc ____ DD _____ e. E _____ Ff ____ Gg ____ Hh ____ Kk ____ Mm ____ Nn ____ RR ____ Ss ____ NN ____
• . Write Ho. Dom if it is homozygous dominant, Ho. Rec. if it is homozygous recessive or He if it is Heterozygous. • • • • AA ____ BB ____ Cc ____ dd ____ FF ____ qq ____ SS ____ TT ____ VV ____ Tt ____ uu ____ WW ____ ii ______ xx ____ bb ____
Law of Segregation • What is segregation – separation of allele pairs • When does this occur? –During meiosis (formation of sex cells) • Why do they segregate? –So each gamete only carries a single copy of each gene.
Meiosis Video • https: //www. youtube. com/watch? v=luq 1 R 4 WAPY
Law of Independent Assortment • What is independent assortment? – Genes/alleles separate independently during meiosis. – Genes don’t influence inheritance of other genes • (Inheriting blue eyes doesn’t mean you’ll automatically inherit blonde hair) • Seed color does not influence seed shape • Dihybrid Crosses (2 trait punnet square) demonstrates this law.
More on genetics…. to be continued.
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