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Published byGrace Fisher Modified over 8 years ago
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Punnett Squares And Meiosis!
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Meiosis: A type of cell division in which a diploid cell (two copies of each gene) divides to form a haploid cell (one copy of each gene). = SPERM and EGG!
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Dominant T - curved thumb/allele Recessive t - not curved allele Dominant T - curved thumb allele Recessive t - not curved allele Tt T t T t
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Punnett Square: A method to determine the likely genotypes and phenotypes of offspring T t T t eggs sperm tt Tt TT Curved thumb Straight thumb Curved thumb
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How to fill in a punnett square
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Using the Punnett Square below, correctly cross a heterozygous brown haired person with a homozygous blonde haired person. Bb x bb B = brown hair allele b = blonde hair allele B b b b bb Bb bb
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b BbBb Bb bb Phenotype: 2 brown hair and 2 blonde hair Genotype: 2 Bb and 2 bb
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Solve the following problems: GIVE THE PHENOTYPE & GENOTYPE! Cross EE x ee (brown eyed person with blue eyed) Cross a wrinkled seed with a homozygous round seed (W = wrinkled w = round) Cross a heterozygous tall person with a heterozygous tall person. Cross a homozygous tall person with a short person
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Mendel’s Laws
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Law of Segregation Two alleles separate from each other during meiosis! Each homologous chromosome pair separates during the formation of the sperm and egg (meiosis!)
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Law of Segregation
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Law of segregation
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Incomplete Dominance Hh (heterozygote) where the functioning allele makes less protein Example: in snapdragon flowers, red is dominant, but less protein pigment is made w/ Rr; the flower is pink (Rr) = pink
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Incomplete Dominance Practice In the budgerigars bird (“budgie”), olive feather color is dominant (GG), dark green is heterozygous (Gg), and light green is recessive (gg). Cross an olive bird and a light green bird. Cross two heterozygous birds
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Codominance When both alleles (forms of a gene) are expressed Blood type is an example of codominance Blood type A is codominant with B Blood type O is recessive to A and B
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Codominance Practice Cross a person with type O blood (oo) with a person who has type A blood (Ao). What are the possible genotypes and phenotypes of their children? G: 2 Ao: 2 oo P: 2: type A blood : 2 type o blood
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Sex-Lined Traits gene carried only on the X chromosome there is no corresponding gene on the y chromosome Cross a non- colorblind male (XBY) with a “carrier” female (XBXb)
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Law of Independent Assortment The distribution of alleles for one trait does not affect the distribution for of alleles for other traits
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Law of Independent Assortment
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