Introduction to Genetics Environmental Science (R/S)

What is Genetics? Study of heredity Genes are passed down from parents to their offspring “Genes” make individual organisms unique Father of Modern Genetics = Gregor Mendel

Mendel’s Work Mendel carried out his experiments on ordinary garden peas because they were easy to work with, they grew quickly, and he could make pure bred plants Determined some traits were: a) Dominant- only one allele is needed for expression (represented by capital letters) b) recessive- two alleles are needed for expression (represented by lower case letters)

Genes and Alleles The different forms of a gene are called alleles For example, blue eyes vs. brown eyes Gene= eye color, 2 alleles= brown and blue In this case, Brown eye color is dominant to blue eye color This means you would need only 1 brown allele to express the phenotype (have brown eyes) In order to have blue eyes, you would have to have 2 alleles to express the phenotype

Punnett Squares Tools used to determine the probability of gene expression (both genotype and phenotype) Traits are assigned letters to represent the two forms of alleles Y= yellow, y= green Y= dominant, y=recessive yy= homozygous (same) Yy= heterozygous (different)