Non Mendelian InheritanceNon Mendelian Inheritance

Exceptions to the ruleExceptions to the rule

Intermediate InheritanceIntermediate Inheritance

When the heterozygous offspring When the heterozygous offspring have a trait that isn’t exactly the trait have a trait that isn’t exactly the trait of either purebred parentof either purebred parent

Incomplete DominanceIncomplete Dominance

Sometimes a cross between two Sometimes a cross between two individuals with two different individuals with two different phenotypes can result in offspring phenotypes can result in offspring with a third phenotype that is a blend with a third phenotype that is a blend of the parents’ phenotypesof the parents’ phenotypes

Example of incomplete Example of incomplete dominance: Snapdragonsdominance: Snapdragons

CodominanceCodominance

In Codominance, the "recessive" & "dominant" traits appear together in the phenotype of hybrid organisms.

red x white ---> red & white spotted

Example of codominance:Example of codominance:Color of cornsnakesColor of cornsnakes

CornsnakesCornsnakes

Example of codominance:Example of codominance:Roan CowsRoan Cows and Horsesand Horses

Red x White Red x White Red and White Red and White Spotted Spotted

Polygenic TraitPolygenic Trait

A single trait that is affected by more A single trait that is affected by more than one genethan one gene

Each gene may be inherited Each gene may be inherited independentlyindependently

What do you think that results in?What do you think that results in?

Example of a polygenic traitExample of a polygenic trait

Eye colorEye color There are genes forThere are genes for

Tone of pigment (what color it is)Tone of pigment (what color it is) The amount of pigmentThe amount of pigment Position of pigments (look at people’s eyes- Position of pigments (look at people’s eyes-

there are many different patterns in the iris)there are many different patterns in the iris)

Eye color continuedEye color continued

Multiple AllelesMultiple Alleles

Many genes have more than just two Many genes have more than just two alleles (forms of the gene)alleles (forms of the gene)

If there are three or more alleles for If there are three or more alleles for a trait, it is called multiple allelesa trait, it is called multiple alleles

Example of multiple alleles: Example of multiple alleles: Human Blood TypeHuman Blood Type

PleiotropyPleiotropy

When a single gene affects more When a single gene affects more than one traitthan one trait

Example of Pleiotropy:Example of Pleiotropy:White CatsWhite Cats

The first effect is the white fur colorThe first effect is the white fur color The second effect is that the cats are The second effect is that the cats are

often deaf in one or both earsoften deaf in one or both ears

Example of Pleiotropy: Cystic Example of Pleiotropy: Cystic FibrosisFibrosis

Environmental EffectsEnvironmental Effects

The environment can influence the The environment can influence the expression of genesexpression of genes

Example of effect of Example of effect of temperaturetemperature

Ptarmigan in the tundra- change Ptarmigan in the tundra- change color depending on the temperature color depending on the temperature and weatherand weather

Soil acidity and hydrangeaSoil acidity and hydrangea

Social ConditionsSocial Conditions

Sex changing Japanese gobiesSex changing Japanese gobies

What else???What else???

Can you think of another factor that Can you think of another factor that could affect the expression of certain could affect the expression of certain genes?genes?