Pea In Your Genes

Gregor Mendel Liked to play with pea Father of Genetics Noted passing of traits from parents to offspring – heredity Study of heredity - Genetics plants.

A single trait can be expressed (shown) in different ways. Allele is the different representation of the same trait. Ex. Seed color: Yellow or Green Yellow is one Allele for Seed Color Green is another Allele

Genotype & Phenotype Genotype – “code” for a trait. Letters we use. Ex. Yy Phenotype – what you actually see. Yellow peas – Use Y to represent Yellow Green peas – Use y to represent Green

Yellow and Green Peas Genotype Phenotype YY – Yellow – Homozygous Dominant Yy – Yellow - Heterozygous yy – Green –Homozygous Recessive The ONLY way a recessive trait is EVER seen is if the GENOTYPE is Homozygous Recessive – or yy.

Three different Genotypes but Two Colors. Why? YY – Yellow Yy – Yellow yy - Green Dominant Allele – rep. by a capital letter – Y Recessive Allele – rep. by a lowercase letter - y Dominant Alleles OVER POWER Recessive Alleles

YY – Homozygous Yellow Yy – Heterozygous Yellow yy – Homozygous Green

Complete Dominance Dominant Allele completely masks recessive allele.

Incomplete Dominance Incomplete dominance = one allele is not completely dominant over the other.

Codominance Codominance= condition in which both alleles for a gene are expressed when present

What to know: Mitosis Cells begin and end 2N Be able to know, draw, and recognize EACH step. Know what the “Big Event” of each step is. Ex. Metaphase – line up middle

Cross-Over Increases Genetic Variety

What to know: Meiosis Prophase I – ONLY stage where Cross-Over occurs Meiosis begins 2N and ends 1N Be able to know, draw, recognize EACH stage of Meiosis. Know what the “Big Event” of each step is.

How do alleles pass from parent to child? y y Punnett Squares What if you cross a Homozygous Yellow Pea (YY) with a Homozygous Green Pea (yy)? y y Y Y Y y y Y Y Y 100% Heterozygous Yellow Peas

Y y y Y Y Y Y y y y y Y 25% Homozygous Yellow 50% Heterozygous Yellow 25% Homozygous Green Genotype Ratio: 1:2:1 y Y Y Y Y y y y y Y

Incomplete and Complete Dominance

Complete Dominance Dominant Allele completely masks recessive allele.

Incomplete Dominance Incomplete dominance = one allele is not completely dominant over the other.

Codominance Codominance= condition in which both alleles for a gene are expressed when present

Dihybrid Cross Start with FOIL Put results of FOIL for parent one at top Put results of FOIL for parent two to the left Distribute like monohybrid cross.

FOIL First Outside Inside Last RrSs RS Rs rS rs

RrSs x RrSs RS Rs rS rs Always results in a 9:3:3:1 Ratio!!! RRSS RRSs