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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