Introduction to Genetics

Objective: I can construct 2 examples of phenotype and genotype using Punnett squares Warm Up: #1. List the stages of mitosis #2. What is happening in this picture? What is it called?

Who was Gregor Mendel? He was known as the “FATHER OF GENETICS” He discovered how traits were inherited GENETICS- study of heredity HEREDITY - the passing of traits from parents to offspring

Mendel’s Peas Mendel did his study on pea plants Pea plants have many traits ( tall/short, purple flowers, white flowers) Pea plants can be self-fertilized or cross fertilized

Generation Parent Generation (P Generation): 1st organisms to be crossed F1 Generation: Offspring of the parent generation F2 Generation: Offspring of the F1 generation

Cross of pure breeding green + yellow pea plant Parent generation is P generation. Green seed and yellow pea seed. Seeds from First generation ( F1) All had yellow seeds. Planted F1 and the Second Generations (F2) was a 3:1 ratio of yellow to green

Genes and Alleles Mendel discovered that each trait is controlled by two factors (alleles) Alleles: different forms of the same gene. Genes-factors that determine your traits

Types of plants 1. True-breeding- produce offspring with only one form of a trait. *Individuals are homozygous, offspring are identical to parents. 2. Hybrids –offspring of true-breeding plants Tall x short =Hybrid

Dominance Some traits are dominant over other Tall x short = all tall offspring (hybrids) *Tall is the dominant trait * Short is recessive Because yellow is dominant it is represented by Capital Y Lowercase y for recessive

Homozygous: organism with two of the same alleles of that trait Homozygous: organism with two of the same alleles of that trait. ( Purebred) * YY yellow seed plant * yy green plants Heterozygous: organism with two different alleles. Yy, dominant trait will be observed * Heterozygous organisms are called hybrids

Law of independent assortment Allele pairs separate independently during gamete formation Traits are passed to offspring independently of one another Alleles for blue eyes and blonde hair are inherited separately from one another

Law of Segregation Alleles for a trait separate when gametes are formed Alleles are then randomly unites at fertilization

GENOTYPE: what genes, letter, the organism has ( TT, Tt, tt) GENOTYPE: what genes, letter, the organism has ( TT, Tt, tt) * the plant with yellow seeds their genotype could be YY or Yy PHENOTYPE: what it looks like ( tall, or short) observable characteristics or outward expression of an allele pair

Monohybrid cross: a single trait. Dominant allele written first Dihybrid Cross: 2 or more traits in the same plant (organism) In peas: round seed(R ) are dominant to wrinkled seeds(r) and yellow seeds (Y) are dominant to green seeds (y)

Punnett Squares To predict the possible offspring of 2 crosses between 2 known genotypes - Easier to keep track of possible genotypes involved in a cross.

Probability Chance of flipping heads is ? ½?