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Punnett Squares. A Punnett square illustrates how the parents alleles might combine in offspring. A Punnett square illustrates how the parents alleles.

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Presentation on theme: "Punnett Squares. A Punnett square illustrates how the parents alleles might combine in offspring. A Punnett square illustrates how the parents alleles."— Presentation transcript:

1 Punnett Squares

2 A Punnett square illustrates how the parents alleles might combine in offspring. A Punnett square illustrates how the parents alleles might combine in offspring. The top of the Punnett Square are one of the parents alleles, the side of the Punnett square shows the other parents alleles for the trait The top of the Punnett Square are one of the parents alleles, the side of the Punnett square shows the other parents alleles for the trait

3 Heterozygous : having dissimilar pairs of alleles for any hereditary characteristic Heterozygous : having dissimilar pairs of alleles for any hereditary characteristic Homozygous : having identical pairs of alleles for any given pair of heredity characteristics Homozygous : having identical pairs of alleles for any given pair of heredity characteristics

4 Mendels Laws of Inheritance 1.Law of Dominance: In heterozygous genotypes, dominant alleles hide recessive alleles when both are inherited by an organism. (Hh means the dominant trait will show up in the phenotype)

5 Mendels Laws of Inheritance 1. The Law of Segregation (separation): Each organism has 2 alleles for a gene. Only one allele from each gene pair will be passed on to the offspring.

6 Homozygous/Heterozygous Cross a homozygous dominant tall plant with a homozygous recessive short plant. Cross a homozygous dominant tall plant with a homozygous recessive short plant. What letters would you use to represent this cross? Dominant trait = tall Dominant trait = tall Recessive trait = short Recessive trait = short T = tall T = tall t = short t = short Hmzg / Htzg

7 What is the genotype of a homozygous dominant tall plant? What is the genotype of a homozygous dominant tall plant? Genotype Genotype % TT % Tt % tt TT TT TT x tt TT x tt What is the genotype of a homozygous recessive short plant? What is the genotype of a homozygous recessive short plant? tt tt t t T TT T Phenotype Phenotype % tall % short Tt

8 2. Cross a heterozygous brown haired rabbit with a homozygous recessive white haired rabbit. o What letters would you use to represent this cross? Dominant trait = brown hair Dominant trait = brown hair Recessive trait = white hair Recessive trait = white hair B = brown B = brown b = white b = white

9 What is the genotype of a heterozygous brown haired rabbit? What is the genotype of a heterozygous brown haired rabbit? Genotype Genotype % BB % Bb % bb Bb Bb Bb x bb Bb x bb What is the genotype of a homozygous recessive white haired rabbit? What is the genotype of a homozygous recessive white haired rabbit? bb bb b b BbBb Phenotype Phenotype % brown % white bb Bb 0 50

10 3.. Cross a homozygous dominant long haired guinea pig with a heterozygous long haired guinea pig. o What letters would you use to represent this cross? Dominant trait = long hair Dominant trait = long hair Recessive trait = short hair Recessive trait = short hair L = long L = long l = short l = short

11 What is the genotype of a homozygous dominant long haired guinea pig? What is the genotype of a homozygous dominant long haired guinea pig? Genotype Genotype % LL % Ll % ll LL LL LL x Ll LL x Ll What is the genotype of a heterozygous long haired guinea pig? What is the genotype of a heterozygous long haired guinea pig? Ll Ll L l LL LL Phenotype Phenotype % long % short LLLl LLLl

12 4. Cross a heterozygous wrinkly elephant with another heterozygous wrinkly elephant. What letters would you use to represent this cross? Dominant trait = wrinkly skin Dominant trait = wrinkly skin Recessive trait = smooth skin Recessive trait = smooth skin W = wrinkly W = wrinkly w = smooth w = smooth

13 What is the genotype of a heterozygous wrinkly-skinned elephant? What is the genotype of a heterozygous wrinkly-skinned elephant? Genotype Genotype % WW % Ww % ww Ww Ww Ww x Ww Ww x Ww What is the genotype of a heterozygous wrinkly-skinned elephant? What is the genotype of a heterozygous wrinkly-skinned elephant? Ww Ww W w WwWw Phenotype Phenotype % wrinkly % smooth Wwww WWWw

14 Phenotype Phenotype % round % wrinkled 5.A plant that is homozygous dominant for round seeds is crossed with a heterozygous plant. What is the probability that the offspring will have wrinkled seeds? RR x Rr RR x Rr R r RRRR RRRr RRRr R = round Genotype Genotype % RR % Rr % rr r = wrinkled


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