Genetics

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 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 AllelesDominant vs. Recessive Alleles (Cont.) Dominant vs. Recessive Alleles 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? 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 have dimples would all the kids have dimples?

Genotype vs. Phenotype Genotype vs. Phenotype Ph enotype- ph ysical trait –can be seen –Brown or blonde Gen otype- gen etic 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 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 dom. For dominant or rec. for recessive next the letter. A ______ C ______ d _______ e _______ F _______ f ______ v ______ P ______ m ______ M ______ Q _______ n ________ b ________ X ________ Y _________

. Write Ho. for homozygous or He. for heterozygous. AA _____ Bb ____ Cc ____ DD _____ eE _____ 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 uq1R4WAPYhttps:// uq1R4WAPY

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.