Inheritance Genes Learning Objectives To understand how traits

Inheritance & Genes

Learning Objectives • To understand how traits are passed from parents to offspring. • To know the difference between dominant and recessive genes. • To be able to construct and interpret Punnett squares. • To determine the expected ratio of phenotypes in a genetic cross.

Key Words Alleles - Alternative form of a gene Genes – the units of inheritance. Genetics - Scientific study of heredity and hereditary variations Genotype - Genetic makeup of an organism Heredity - Transmission of characteristics from parents to offspring Heterozygous - Having tow different alleles for a given gene Homozygous - Having two identical alleles for a given gene Pedigree - Family tree representing the occurrence of heritable traits in parents and offspring across a number of generations • Phenotype - The expressed traits of an organism; outward appearance • Punnett square - Diagram used in the study of inheritance to show the results of random fertilization. • •

Genes are the units of Inheritance

Dominant/Recessive Inheritance Homozygous parents CROSSCHART BOTH parents are PURE-BREEDING (CAN ONLY PASS ON ONE TYPE OF ALLELE for that TRAIT.

Dominan/Recessive Inheritance Heterozygous parents CROSSCHART Both parents have a copy of TWO DIFFERENT ALLELES that can be passed on for that TRAIT.

Punnett Squares Ff = “carrier” of cystic fibrosis

Pedigree Analysis