biology i - genetics 1-12 novak gregor mendel 1822-1884

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  • Biology I - GENETICS1-12 Novak

  • Gregor Mendel1822-1884

  • MENDELS PRINCIPLES

  • I. ALLELESAny organism has two units of heredity (genes) for each trait in every body cell

  • II. SEGREGATIONThe two units (genes) for a trait are separated in the cell; one gene is found on a chromosome while the other is located in the same place on its partner (homologous) chromosome

  • III. DOMINANCE A. When two genes of a trait are different in the cells of the organism, the gene that shows up is the dominant while the gene that remains hidden is the recessive B. Combinations of the two genes (genotypes)1. Homozygous (pure) dominant - both genes are dominant2. Homozygous (pure) recessive - both genes are recessive3. Heterozygous (hybrid) - one gene is dominant & the other is recessive

  • IV. RECOMBINATION - (INDEPENDENT ASSORTMENT)In each new generation there is a complete new rearrangement of the units of heredity (genes)

  • Following the GenerationsCross 2 Pure Plants TT x ttResults in all Hybrids TtCross 2 Hybrids get 3 Tall & 1 Short TT, Tt, tt

  • Generation GapParental P1 Generation = the parental generation in a breeding experiment.F1 generation = the first-generation offspring in a breeding experiment. (1st filial generation)From breeding individuals from the P1 generationF2 generation = the second-generation offspring in a breeding experiment. (2nd filial generation) From breeding individuals from the F1 generation

  • Mendels Experimental Results

  • Thomas Hunt Morgan1866-1945

  • Incomplete Dominance (blending inheritance)

  • INCOMPLETE DOMINANCEA condition in which both alleles for a characteristic are partially expressed

  • Incomplete DominanceF1 hybrids have an appearance somewhat in between or a blend of the phenotypes of the two parental varieties.Example: snapdragons (flower)red (RR) x white (WW)

    R = red flowerW = white flower

  • Incomplete DominanceWW

  • Incomplete Dominance

  • CODOMINANCEA condition in which both alleles for a characteristic are fully expressed

  • Codominant white and pink

  • Codominant white and pink

  • Homozygous Red

  • Hereford Red

  • Homozygous white

  • Roan hybrid

  • Roan hybrid

  • Codominant cross

  • Sex-Linked Inheritance

  • Color Blindness

  • normal - trichromatic color vision protanopia red-green blindness (no red cones) deutanopia red-green blindness (no green cones) tritanopia blue-yellow blindness (no blue cones) typical achromatopsia (no cones; rod monochromat) protanomaly (anomalous red cones) deutanomaly (anomalous green cones) tritanomaly (anomalous blue cones) atypical achromatopsia (low cones; cone monochromat)

    TYPES OF COLOR BLINDNESS

  • Red Green Color BlindnessMale1.01%Female0.02%

  • Sex-linked TraitsTraits (genes) located on the sex chromosomesSex chromosomes are X and YXX genotype for femalesXY genotype for malesMany sex-linked traits carried on X chromosome

  • Hemophilia

  • Female Carriers

  • The effects of hemophilia

  • Human BloodCoagulationCascade

  • DIHYBRID INHERITANCE

  • Pea PlantsTall = TT, TtShort = ttHeightSeed ColorYellow = YY, YyGreen = yyLets cross a homozygous tall (TT), homozygous yellow seed (YY) plant with a short (tt), green seed (yy) plant.TTYY x ttyyThese are the genotypes of the two plants.

  • Independent AssortmentMendels principle of Independent Assortment states that genes for different traits can segregate independently during the formation of gametes (eggs & sperm in animals, eggs and pollen in plants).TTYYTYFirst Twith first YGamete 1 = sperm, egg, pollen . . .

  • Independent AssortmentMendels principle of Independent Assortment states that genes for different traits can segregate independently during the formation of gametes (eggs & sperm in animals, eggs and pollen in plants).TTYYTYTYFirst Twith second YGamete 1Gamete 2

  • Independent AssortmentMendels principle of Independent Assortment states that genes for different traits can segregate independently during the formation of gametes (eggs & sperm in animals, eggs and pollen in plants).TTYYTYTYTYSecond Twith first YGamete 1Gamete 2Gamete 3

  • Independent AssortmentMendels principle of Independent Assortment states that genes for different traits can segregate independently during the formation of gametes (eggs & sperm in animals, eggs and pollen in plants).TTYYTYTYTYYTSecond Twith second YGamete 1Gamete 2Gamete 3Gamete 4

  • Dihybrid Punnett Square - F1P1 = TTYYP2 = ttyyWill be F1 Generation

    TYTYTYTYtytytyty

  • Dihybrid Punnett Square - F1

    TYTYTYTYtyTTYytyTTYytyTTYytyTTYy

  • Dihybrid Punnett Square - F1

    TYTYTYTYtyTtYyTtYyTtYyTtYytyTTYYTtYYTtYYTTYYtyTTYYTTYYTTYYTTYYtyTTYYTTYYTTYYTTYY

  • Dihybrid Punnett Square - F1

    TYTYTYTYtyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYy

  • Dihybrid Punnett Square - F1Genotype ratio:TtYy - 16/16Phenotype ratio:Tall, Yellow - 16/16

    TYTYTYTYtyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYy

  • Dihybrid Punnett Square F2We need to pair up the genes which can be given to each gamete (egg and pollen).Lets cross two of the plants from the F1 generationx.TYTytYytWe need to pair up the genes

    TYTYTYTYtyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYytyTtYyTtYyTtYyTtYy

  • Dihybrid Punnett Square F2Both the plants can give the same gene combinations to their gametes, so the pairs along the top and down the side are the same.

    TYTytYtyTYTytYty

  • Dihybrid Punnett Square F2When you pair up the gametes from the two plants, always put like letters together and within the like letters, put the CAPITAL letter in front of the lowercase letter.

  • Dihybrid Punnett Square F2Your Turn!!

    TYTytYtyTYTTYYTTYyTtYYTtYyTy????????????????tY????????????????ty????????????????

  • Dihybrid Punnett Square F2F2 generation

    TYTytYtyTYTTYYTTYyTtYYTtYyTyTTYyTTyyTtYyTtyytYTtYYTtYyttYYttYytyTtYyTtyyttYyttyy

  • Dihybrid Punnett Square F2Genotype and phenotype ratios?

    TYTytYtyTYTTYYTTYyTtYYTtYyTyTTYyTTyyTtYyTtyytYTtYYTtYyttYYttYytyTtYyTtyyttYyttyy

  • F2 Genotype RatioTTYY - 1TTYy - 2TtYY - 2TtYy - 4TTyy - 1Ttyy - 2ttYY - 1ttYy - 2ttyy - 1

  • F2 Phenotype RatioTTYY - 1TTYy - 2TtYY - 2TtYy - 4TTyy - 1Ttyy - 2ttYY - 1ttYy - 2ttyy - 1Tall, Yellow - 9Tall, Green - 3Short, Yellow - 3Short, Green - 1

  • Another Mendelian Dihybrid Problem

  • Dihybrid F2 Results

  • Dihybrid F2 Results

  • The End

  • *******

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