GeneticsGenetics

What is an ALLELe?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 AllelesDominant 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 Dominant vs. Recessive Alleles (Cont.)(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?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?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. PhenotypeGenotype vs. Phenotype•Phenotype-

physical trait– can be seen– Brown or blonde

•Genotype- genetic makeup– Alleles inherited– (not seen BB, Bb)

Genotype/Phenotype PracticeGenotype/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 HeterozygousHomozygous vs Heterozygous

• PREFIXES:

– HOMO=SAME alleles for a specific trait ( TT or tt)

– HETERO=DIFFERENT alleles for a specific trait (Tt or Bb)

Practice-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 ProblemsPractice ProblemsWill the following plants be tall or

short? T=tall and t=shortTtTTttAre the following plants homozygous or

heterozygous?TTTttt

PracticePractice

What is the phenotype of the following plants?

TtTTtt

• 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 SegregationLaw of Segregation•What is segregation

– separation of alleles•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.

Law of Independent Law of Independent AssortmentAssortment• 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 More on genetics….to be continued.continued.

Hot Celebrities’ allelesHot Celebrities’ alleles

• Think of the hottest looking male/female celebrities you can think of.

• Write their names. Next to their names list the 3 alleles they have that make them so attractive.

• Be prepared to share your PG-13 rated alleles

Mom &/or Dad got it But you don’tMom &/or Dad got it But you don’t

• Picture what your parents look like

• List some traits one or both parents have but you don’t. For ex: eye color, hair color, attached ear lobes, dimples, tall, short, etc.

• You may have inherited some traits but they’re hidden. Here is why………