Heredity!!!Heredity!!!

Passing on traits from parents Passing on traits from parents to offspring to offspring

Gregor MendelGregor Mendel

Austrian MonkAustrian Monk ““Father of Father of

Genetics”Genetics” 1866 Published 1866 Published

FindingsFindings

Mendel SezMendel Sez

Genes inherited from parents. 1 gene from Genes inherited from parents. 1 gene from mom, 1 gene from dad mom, 1 gene from dad

There are alternate versions of genes (all There are alternate versions of genes (all genes are not exactly the same). genes are not exactly the same). These are These are called alleles.called alleles.

If an organism has two alleles that are different If an organism has two alleles that are different only 1 is shownonly 1 is shown

Gametes (sex cells) only carry one allele, not Gametes (sex cells) only carry one allele, not bothboth

NO BLENDING NO BLENDING

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Alleles Alleles Alleles are different types of the same geneAlleles are different types of the same gene Always have 2 alleles for each gene in an Always have 2 alleles for each gene in an

individualindividual Alleles can be recessive or dominantAlleles can be recessive or dominant

Recessive alleles do not show the trait in the presence Recessive alleles do not show the trait in the presence of a dominant alleleof a dominant allele

Dominant alleles ALWAYS show the traitDominant alleles ALWAYS show the trait

Earlobes: Free ear lobes (dominant trait)Attached ear lobes (recessive trait)

Free Attached

PhenotypePhenotype The physical appearance of the trait. The The physical appearance of the trait. The

appearance of an allele. appearance of an allele.

Gold Color Allele

White ColorAllele

Black ColorAllele

Yellow ColorAllele

GenotypeGenotype

The actual alleles: WW or Ww or wwThe actual alleles: WW or Ww or ww W is purple allele and dominant W is purple allele and dominant w is white allele and recessivew is white allele and recessive

This plant could be WW or WwThis plant could only be ww

Allele CombinationsAllele Combinations

Cells have 2 alleles of for each geneCells have 2 alleles of for each gene HeteroHeterozygous: both alleles are differentzygous: both alleles are different

WwWw HomoHomozygous: both alleles are the samezygous: both alleles are the same

WW or wwWW or ww

Special Note: In order to display a recessive characteristic, individual must be homozygous recessive.

GenerationsGenerations Parents: P GenerationParents: P Generation First Offspring Generation: FFirst Offspring Generation: F11

Second Offspring Generation: FSecond Offspring Generation: F22

P Generation F2 GenerationF1 Generation

Laws of HeredityLaws of Heredity

Law of SegregationLaw of Segregation 2 Alleles segregate (separate) when 2 Alleles segregate (separate) when

gametes (sex cells) are formed. gametes (sex cells) are formed. Remember meiosis…Remember meiosis…

Law of Independent AssortmentLaw of Independent Assortment Alleles of different genes separate Alleles of different genes separate

independently of each other independently of each other