Monday, 1/25/10 (Genetics)Monday, 1/25/10 (Genetics)•Check Grades•Check Grades•Genetics Lesson•Genetics Lesson•Bring Large Milk Cartons (Extra Credit!!)•Bring Large Milk Cartons (Extra Credit!!)  Homework, Due Thursday / FridayHomework, Due Thursday / Friday•Read pgs 165-169•Read pgs 165-169•Answer #'s 1-5 pg 169•Answer #'s 1-5 pg 169  Tuesday / Wednesday, 1/26-27Tuesday / Wednesday, 1/26-27•More About Genetics•More About Genetics•Punnett Squares Packet•Punnett Squares Packet-Single Factor Crosses-Single Factor Crosses  Thursday / Friday, 1/28-29Thursday / Friday, 1/28-29•Discuss and Collect Homework•Discuss and Collect Homework•Correct Punnett Squares Packet #'s 1-10•Correct Punnett Squares Packet #'s 1-10•Plant Corn for Genetics Lab•Plant Corn for Genetics Lab•Start Genetics Problems 1•Start Genetics Problems 1

GeneticsGenetics

Gregor MendelGregor Mendel

This is Gregor MendelThis is Gregor Mendel He loved mathHe loved math He loved He loved peaspeas So he worked at a So he worked at a

monastery to find out monastery to find out how certain how certain traitstraits were were passed from passed from parents to parents to offspringoffspring

He studied traits and He studied traits and inheritanceinheritance

Peas – The Lucky PlantPeas – The Lucky Plant

Most famous for his Most famous for his work with work with peaspeas Peas come in many Peas come in many

varietiesvarieties Control Control pollinationpollination Peas have Peas have distinctive distinctive

characteristicscharacteristics

Pea plants have seven observable characteristics.Each characteristic has two possible traits.

Characteristic Possible TraitPlant Height Long or Short Stems

Flower Position on Stem Axial or Terminal

Pod Color Green or Yellow

Pod Appearance Inflated or constricted

Seed Texture Smooth or Wrinkled

Seed Color Yellow or Green

Flower Color Purple or White

Mendel’s Work On Pea Mendel’s Work On Pea PlantsPlants

By controlling plant pollination (fertilization), Mendel was able to create pea plants that were true-breeding or “pure” for each trait.

True breeding parent plants always produce offspring with the same trait.

Flower Color ExampleFlower Color Example

A plant true-breeding for purple flowers will always produce offspring with purple flowers.

True breeding plants are called the P1 generation.

Flower Color ExampleFlower Color Example

He then crossed a He then crossed a true breedingtrue breeding purplepurple plants with a plants with a true breedingtrue breeding whitewhite plants plants

This is the This is the PP11 generation generation

PP1 1 Generation = true breeding Generation = true breeding parentparent

Flower Color ExampleFlower Color Example

The offspring of the PThe offspring of the P11 generation is the generation is the

FF11 generation generation 11stst Filial (son/daughter) Filial (son/daughter)

The offspring were The offspring were hybridshybrids because the because the parents had parents had different traitsdifferent traits PurplePurple x x WhiteWhite

All offspring were All offspring were PurplePurple!!

FF1 1 = 1= 1stst Offspring Generation Offspring Generation

Dominant and RecessiveDominant and Recessive

PurplePurple “beat”“beat” WhiteWhite in the F in the F11 generation generation

Mendel called the trait that Mendel called the trait that appearedappeared in in the F1 generation the the F1 generation the dominantdominant trait. trait.

The trait that The trait that did not appeardid not appear in the F1 in the F1 generation is the generation is the recessiverecessive trait. trait.

Law of SegregationLaw of Segregation

States that for each trait there are States that for each trait there are 2 2 controlling factorscontrolling factors

During gamete formation (meiosis) During gamete formation (meiosis) these these 2 factors separate2 factors separate Each gamete gets Each gamete gets 1 and only 1 factor1 and only 1 factor

When egg is fertilized, the egg now When egg is fertilized, the egg now has has 2 factors per trait2 factors per trait

Crossing F1 GenerationCrossing F1 Generation

Mendel let the plants from the F1 Mendel let the plants from the F1 generation generation self pollinateself pollinate..

Did this make Did this make true breedingtrue breeding plants? plants? No!No!

About About ¼ of the plants¼ of the plants showed the showed the recessiverecessive trait. trait. WhiteWhite

FF22 Generation Generation

The White trait was The White trait was hidden in the DNAhidden in the DNA

Law of independent Law of independent assortmentassortment

This law states that factors (This law states that factors (allele pairsallele pairs) for ) for different characteristics (different characteristics (genegene) separate ) separate independentlyindependently during the formation of during the formation of gametesgametes..

Therefore, traits are transmitted to offspring Therefore, traits are transmitted to offspring independently of one anotherindependently of one another. .

Example:Example: White flowering plant (recessive) with green pod White flowering plant (recessive) with green pod

(dominant)(dominant)

TermsTerms HomozygousHomozygous = Both alleles are the = Both alleles are the samesame

PP or ppPP or pp

HeterozygousHeterozygous = alleles are = alleles are differentdifferent 1 1 dominantdominant gene, 1 gene, 1 recessiverecessive

PpPp

GenotypeGenotype = Which = Which genesgenes are present are present PP = purplePP = purple Pp = purplePp = purple pp = whitepp = white

Phenotype = Phenotype = Physical Physical appearanceappearance, What we see!, What we see! Punnett SquaresPunnett Squares