How TRAITS are passedHow TRAITS are passed

Complete vocabulary for Complete vocabulary for CHAPTER 5, section 1 (pages 126-CHAPTER 5, section 1 (pages 126-

132)132)

The way it works…

• When organisms When organisms reproduce, traits arereproduce, traits arepassed from parent to passed from parent to offspring.offspring.

• These traits are carried in These traits are carried in DNA, the genetic material DNA, the genetic material found in a cell’s nucleus.found in a cell’s nucleus.

• DNA acts like a blueprint.DNA acts like a blueprint.

Your parents…Your parents…

• Each parent has two genes (or letters) for a trait. These letters are called allelesalleles.

• Capital letters are called Dominant allelesDominant alleles. When these alleles are present, they take over or show. They are the “stronger” alleles.

• Lower case letter are recessive allelerecessive alleles and are the “weaker” of the alleles.

Genotype and Phenotype

• GenotypeGenotype – the – the inherited alleles inherited alleles (letters)(letters)

• PhenotypePhenotype – what – what the alleles look like the alleles look like when inherited.when inherited.

(physical feature)(physical feature)

Represented by hh

Represented by Red Hair

Homozygous and Heterozygous

• IF the genes are the IF the genes are the same, they are same, they are homozygoushomozygous

• – “– “homo” means samehomo” means same

• IF the genes are IF the genes are different, they are different, they are heterozygousheterozygous

• – “– “hetero” means hetero” means differentdifferent

How can we figure out the How can we figure out the PROBABILITY?PROBABILITY?

• Using Punnett Squares Punnett Squares allow us to show what the offspring could look like

• Allows us to calculate probabilityprobability (likelihood) of certain genotypes and phenotypes to occur

• Punnett Square PRACTICE

Genetics since Mendel Genetics since Mendel messed with the Pea Plantsmessed with the Pea Plants

• Incomplete DominanceIncomplete Dominance– Intermediate phenotypeIntermediate phenotype– Cross between two Cross between two

homozygous parentshomozygous parents– RR= red; rr= white; Rr= RR= red; rr= white; Rr=

pinkpink

• Multiple AllelesMultiple Alleles– Trait controlled by more Trait controlled by more

than two allelesthan two alleles– Blood type (depends on Blood type (depends on

how two alleles are paired how two alleles are paired up)up)

– A, B, AB, OA, B, AB, O

• Polygenic InheritancePolygenic Inheritance– Combination of many genesCombination of many genes– Colors vary depending on # Colors vary depending on #

of dominant alleles presentof dominant alleles present

Patrick & PatriciaPatrick & PatriciaProud Parents of Proud Parents of PaddyPaddy

If you fail to follow If you fail to follow instructions, your instructions, your

grade will end up in grade will end up in the toilet and you the toilet and you don’t want that.don’t want that.