GENES TO TRAITS KEY CONCEPT Genes encode proteins that produce a diverse range of traits.

The same gene can have many versions. A gene is a piece of DNA that directs a cell to make a certain protein. Each gene has a locus, a specific position on a pair of homologous chromosomes.

An allele is any alternative form of a gene occurring at a specific locus on a chromosome. Each parent donates one allele for every gene. Homozygous describes two alleles that are the same at a specific locus. Heterozygous describes two alleles that are different at a specific locus.

Genes influence the development of traits. All of an organism’s genetic material is called the genome. A genotype refers to the makeup of a specific set of genes . A phenotype is the physical expression of a trait. Bb (genotype)  brown hair (phenotype)

Phenotype – the traits that are actually expressed by an individual Examples: Anemic Brown Hair Blue Eyes Fast Runner Widow’s peak Attached ear lobes

Genotype – the set of alleles an individual inherited from their parents for a trait. If your dad gave you the Brown hair gene (B) and your mom gave you the blond hair gene (b) your genotype would be ………Bb. If your mom gave you the gene to be a fast runner (r) and your dad also gave you fast runner gene (r) then your genotype would be If your mom gave you the gene to be tall (T) and your dad gave you the gene to be short (t) then your genotype would be

For every gene an allele can be dominant or recessive. Dominant alleles-  Over power other alleles and are always shown  Will sometimes show up in every generation.  Shown with an uppercase letter ( R ) Recessive alleles-  Will be hidden by dominant genes  Only show up if there are two copies  Shown with a lowercase letter ( r )

Dominant and Recessive Allele Examples Trait Dominant Recessive Widows Peak Have Peak W No Peak w Earlobe Free Hanging E Attached e Petal Color Purple P White p Eye Color Brown B Blue b Any time an organism has at least one dominant allele the dominant trait will be show. Circle the ones that will be dominant? BB ee Bb Ww Pp ww

Homozygous and Heterozygous Homozygous – when an individual has two of the same alleles (both dominant or both recessive) Heterozygous – when an individual has one dominant and one recessive allele Circle the homozygous genotypes dd Gg Ll Hh Jj PP LL HH jj Pp gg DD Put an X on the genotypes that will show a dominant trait.