 Heredity  The passing of traits from parents to offspring  The traits you have resemble your parents  These traits can include ◦ Eye color ◦ Shape of Eyes ◦ Color of your hair ◦ Height

 Gregor Mendel  Mendel: Austrian Monk, Father of Genetics  Genetics- branch of biology focusing on heredity  Crossed pea plants, counted offspring, analyzed data

 Why are pea plants useful for genetics?  1. Traits exist in 2 opposing forms, without intermediates  2. Have male and female organs  Easily control mating (self- fertilization or cross- pollination)  3. Small, grow easily and quickly, produce many offspring

 Monohybri d Cross  Monohybrid Cross: Involves one pair of contrasting traits  For Example: ◦ Crossing a plant with purple flowers and a plant with white flowers

 True Breeding  Step 1: Mendel wanted to create a “Parental generation” also called the “P” generation  True Breeding: Self pollinated pea plants so all the offspring would display only one form of the trait  Ex: A purple flowering plant only produces purple flowers  Why would this be important?

Mendel’s Study of Traits – Step 2 F1 Generatio n Step 2: Cross pollinated two P generation plants (Purple and White flowers) Called the offspring from the P generation the F 1 generation (First) Results: All were purple flowers

 F2 Generation  Step 3: The F 1 Generation self pollinated.  The offspring from the F 1 generation was called the F 2 generation  Results: Three purple flowers, one white flower

 What were the results of the F 1 Generation?  What were the results of the F 2 generation?  What should Mendel’s conclusion be?

 Give one reason why pea plants are good subjects for genetic experiments  Why was it important that Mendel performed true breeding for the P generation?  What did Mendal call each generation?

 Mendel’s Hypotheses  1. Individuals inherit 2 copies of each gene (trait)- one from each parent ◦ Gametes carry only one allele for each inherited trait  2. Alleles- different contrasting versions of each gene (one from each parent)  Ex: Brown eyes vs. Blue eyes

 Mendel’s Hypothese s  3. When 2 different alleles are present the Dominant one is expressed  4. Recessive- trait that’s not expressed when the dominant allele is present

 Genetics Terms  In the following gentoype which letter represents the dominate gene?  Which letter represents the recessive gene?

 Genetics Terms  Homozygous- 2 alleles of a gene are the same (PP or pp)  Heterozygous- if the 2 alleles for a gene are different (Pp) ◦ Only the dominant allele is expressed (masks the recessive allele)

 Genetics Terms  Genotype- allele combinations (genes) ◦ Ff- Heterozygous ◦ FF- Homozygous dominant ◦ ff- Homozygous recessive  Phenotype: is the physical appearance of the trait  Ex: If “B” equals brown eyes and the genotype is Bb the phenotype (expressed trait) would be Brown eyes

Whiteboards – Quick Questions  What would be the genotype for an individual heterozygous for the “F” trait?  Ff  What would be the phenotype for an individual whose genotype is Tt where T is tall and t is short?  Tall

Whiteboards – Quick Questions  Give an example of a heterozygous trait  Ex: Ff  Give an example of a homozygous trait  Ex: FF, ff  What would be the genotype for an individual heterozygous for the “F” trait?  Ff  What would be the phenotype for an individual whose genotype is Tt where T is tall and t is short?  Tall

Laws of Heredity Law of segregati on 1. Law of Segregation: Allele’s separate during meiosis to produce gametes F 1 generation (zygote) has allele’s for each trait by both parents

 Law of Independent Assortment  2. Law of Independent Assortment: Alleles of genes separate independently of one another during gamete formation  Ex: Alleles for plant height separate independently of the alleles for flower color  Results: The inheritance of one trait does not influence the inheritance of another – COMPLETELY SEPARATE

 What is the Law of Segregation?  What is the Law of Independent Assortment?  Identify the phenotypes of rabbits with the genotypes Bb and bb, where B- black coat and b- brown coat.