Intro to Genetics

Terms to know before we start Gene – A section of DNA that codes for a protein that determines a trait (physical characteristic)

Allele vs. Trait Allele – alternate forms of a gene Ex. Trait – Eye color Alleles – Blue, green, brown

You try it!!!!! This section of the chromosome codes for hair color. What is the trait coded for by this gene? What are the alleles for the gene?

Alleles can be dominant or recessive Dominant – allele that is expressed when present shown with a ____CAPITAL_____ letter EX: B ~ allele for brown eyes Recessive – allele that is hidden when dominant allele is present shown with a ____lower______ case letter EX: b ~ allele for blue eyes

Genotype vs. Phenotype Genotype: the two alleles an organism has for a trait ~ AA or Aa Phenotype: the physical appearance of the organism ~ red eyes/white eyes

Homozygous vs. Heterozygous Homozygous – two same alleles; purebred EX. BB or bb Heterozygous – two different alleles; hybrid or carrier EX. Bb

Which chromosome set is heterozygous?

Talk to a Partner: Determine the genotype and phenotype of each flower