Gregor Mendel Father of Genetics Mendel conducted experiments

Gregor Mendel: Father of Genetics • Mendel conducted experiments using garden pea plants • Cross pollinated flowers and observed traits in offspring BIO. B. 2. 1. 1 Describe & predict observed patterns of inheritance (i. e. dominant, recessive, codominance, incomplete dominance, sex-linked, polygenic and multiple alleles).

Pea Plant Traits

Mendel’s Experiment • Mendel developed a true-breeding parent generation, P generation. • True-breeding purple flowered plants always produce purple flowered offspring. • Mendel crossed purple & white flowered plants. The offspring are called the first filial generation, F 1 generation. They all had purple flowers. • The offspring of the F 1 generation is called the F 2 generation.

Mendel’s Observations • The observed trait is called dominant. • The dominant trait is represented with uppercase letters. • The hidden trait is called recessive. • The recessive trait is represented with lowercase letters.

Genotype Determines Phenotype! • The physical appearance is called phenotype. • For each trait, we have two alleles, or versions of a gene. We get one allele from each parent. • Our set of alleles determines our genotype. • PP = genotype Purple = phenotype • pp = genotype white = phenotype

What is a Gene? • A gene is the basic unit of heredity. • A gene is a segment of DNA on a chromosome that describes how to make a certain protein. • Each gene is located at a specific locus on the chromosome. • A genome is all of the genetic information for an organism.

What will be the genotypes of the offspring? ______

Same or Different Alleles? • If both alleles are the same they are called homozygous. • Homozygous Dominant = PP • Homozygous Recessive = pp • If the alleles are different it is called heterozygous. • Heterozygous = Pp

TT x Tt Tt x Tt

Law of Independent Assortment • Pairs of alleles separate independently during meiosis as long as they are on different chromosomes or far apart on the same chromosome. Ex. Seed shape and seed color

Non-Mendelian Patterns of Inheritance: Codominance Incomplete Dominance Sex-linked Polygenic Multiple Alleles

Codominance Produces Offspring with Both Phenotypes Expressed

Incomplete Dominance Produces a Blending in the Phenotype

Colorblindness is Sex-Linked

Pedigree shows the typical inheritance pattern found in red-green color-blindness

Sickle Cell Anemia is Sex-Linked

Polygenic Traits • Many genes code for a single trait. • You typically see a wide variety of phenotypes as a result. • Examples: Skin color, Hair color, Eye color, Human height