Genetics EOC Genetics EOC RemediationRemediation

Some definitions to knowSome definitions to know

Gregor Mendel - the Father of GeneticsGregor Mendel - the Father of Genetics Trait - a characteristic that can be passed Trait - a characteristic that can be passed

to offspringto offspring Genotype – the pair of genes that make up Genotype – the pair of genes that make up

a trait (one from mom, one from dad)a trait (one from mom, one from dad) Aa, AA, aaAa, AA, aa

Phenotype – What the trait looks like Phenotype – What the trait looks like Black or brown fur colorBlack or brown fur color

Independent assortment means Independent assortment means that genes are separated during that genes are separated during meiosis, and each egg and sperm meiosis, and each egg and sperm

is unique. is unique.

Punnett squares are used to predict Punnett squares are used to predict the genotype and phenotype of the the genotype and phenotype of the

offspringoffspring

Punnet Squares and RatiosPunnet Squares and Ratios

A test cross is used to determine A test cross is used to determine the genotype of an unknown parentthe genotype of an unknown parent

Types of DominanceTypes of Dominance

CompleteComplete One allele is dominant and one is recessiveOne allele is dominant and one is recessive B allele for black furB allele for black fur b allele for brown furb allele for brown fur

If the genotype is Bb, the fur would be black, If the genotype is Bb, the fur would be black, because black is dominantbecause black is dominant

Practice crossesPractice crosses

FlowerFlower Red is dominantRed is dominant White is recessiveWhite is recessive Cross a homozygous Cross a homozygous

dominant red flower dominant red flower with a heterozygous with a heterozygous red flower. red flower.

What are the What are the genotypic and genotypic and phenotypic ratios?phenotypic ratios?

SeedsSeeds Green is dominantGreen is dominant Yellow is recessiveYellow is recessive Cross a homozygous Cross a homozygous

recessive yellow seed recessive yellow seed with a homozygous with a homozygous dominant green seed.dominant green seed.

What are the What are the genotypic and genotypic and phenotypic ratios?phenotypic ratios?

Types of DominanceTypes of Dominance

IncompleteIncomplete When neither allele is dominant and the When neither allele is dominant and the

phenotype is intermediate or a blend of the phenotype is intermediate or a blend of the two alleles.two alleles.

R is the allele for red flowers R is the allele for red flowers

R’ is the allele for white flowersR’ is the allele for white flowers

The genotype RR’ would produce pink flowersThe genotype RR’ would produce pink flowers

Incomplete DominanceIncomplete Dominance

Long water melon (LL) * Round Long water melon (LL) * Round watermelon (L’L’)watermelon (L’L’)

Do the crossDo the cross What is the genotypic ratio?What is the genotypic ratio? What is the phenotypic ratio? What is the phenotypic ratio?

Remember – The phenotype in this case has Remember – The phenotype in this case has 3 possibilities, LL long : L’L’ round: LL’ oval3 possibilities, LL long : L’L’ round: LL’ oval

Types of DominanceTypes of Dominance

CodominanceCodominance When both alleles are dominant and each When both alleles are dominant and each

allele is expressed in the traitallele is expressed in the trait

Type AB blood has both A and B antigens on itType AB blood has both A and B antigens on it

Punnet Square For Blood TypesPunnet Square For Blood Types

IA IB

i

i

Multiple alleles vs. polygenic Multiple alleles vs. polygenic inheritanceinheritance

Multiple allelesMultiple alleles more than 2 forms of more than 2 forms of

a genea gene Bloodtype allelesBloodtype alleles

• IIAA

• IIBB

• ii

Polygenic inheritancePolygenic inheritance When two or more When two or more

genes work together to genes work together to give you one traitgive you one trait

Ex. Hair and eye colorEx. Hair and eye color

Sex linked genes are on the sex Sex linked genes are on the sex chromosomeschromosomes

(colorblindness and hemophilia)(colorblindness and hemophilia)

XX = normal femaleXX = normal female

XXhhX = carrrier femaleX = carrrier female

XXhhXXh h == hemophiliac hemophiliac femalefemale

A female who is a carrier A female who is a carrier does not have that does not have that trait! She is not sick at trait! She is not sick at all. She won’t even all. She won’t even know that she carries know that she carries that gene.that gene.

XY = normal maleXY = normal male XXhhY = hemophiliac maleY = hemophiliac male

Males only have I X Males only have I X chromosome. chromosome.

They cannot be carriers. They cannot be carriers. This is why sex linked This is why sex linked

disorders are more disorders are more common in mencommon in men

Pedigrees show the inheritance of Pedigrees show the inheritance of traits through familiestraits through families

Hemophilia – Offspring of Queen Hemophilia – Offspring of Queen VictoriaVictoria

Chromosome map shows all the Chromosome map shows all the genes on single chromosomegenes on single chromosome

Karyotypes show the complete set Karyotypes show the complete set of chromosomes that a human hasof chromosomes that a human has

BiotechnologyBiotechnology Gel electrophoresisGel electrophoresis

Used in DNA fingerprinting to match DNA at a Used in DNA fingerprinting to match DNA at a crime scene with a suspect.crime scene with a suspect.