Mendels Principles of Inheritance By INSERT YOUR NAME
Mendel’s Principles of Inheritance By INSERT YOUR NAME HERE
Principle of Dominance Mendel’s Observations n n n Mendel observed that all plants in the next generation, called the F 1 generation, showed the presence of yellow seeds. None of the offspring had green seeds. The green allele seems to completely disappear in this generation. w R Rw Rw Key R = round w = wrinkled w
Principle of Dominance My Conclusions My dad has blue eyes and my mom has brown eyes. But, all 3 of us kids have brown eyes. This makes me guess that brown is a dominant gene for eye color in humans. l Key R Rl Rl R = brown l = blue l
Principle of Segregation Mendel’s Observations n n n Mendel observed that approximately 3/4 th of the F 2 generation plants showed the presence of yellow seeds. The remaining 1/4 th show green seeds. The observations were consistent, with any character that Mendel studied. R w R RR Rw ww
Principle of Segregation My Conclusions Thinking about my example with eye color in my family. If I marry someone with brown eyes, but the same mix of brown and blue eye color alleles from their parents, then some of our kids might have blue eyes, based on the probability of the recessive blue trait showing up as both alleles for one of our kids. R Key R RR Rl ll R = brown l = blue l
Principle of Independent Assortment Mendel’s Observations n n n When a true breeding plant for yellow round seeds is crossed with a true breeding plant for green wrinkled seeds, the F 1 offspring were all yellow round. Then when F 2 plants were obtained after F 1 selffertilization, 9/16 th of the plants showed the dominant parental trait and 1/16 th showed the recessive parental trait. However, the remaining plants, about 6: 16, express phenotypes different from those of either of the parents. – In our example, these would be yellow wrinkled and green round seeds.
Principle of Independent Assortment Punnett Square n Cross a tall plant with lavender flowers with a short plant with white flowers. Then take an F 2 generation cross TL Tw s. L sw Key T = tall s = short TL Tw L = lavendar w = white TTLL TTLw Ts. LL TTLw TTw w Ts. LL Ts. Lw Tsw w Ts. Lw ss. LL ss. Lw s. L sw Ts. Lw Tsw w ss. Lw ssww
Principle of Independent Assortment My Conclusions Thinking one more time about my example with eye color in my family. If I marry someone with blue eyes this time and if they have blond hair and I have black hair, we will not just produce children with either black hair brown eyes combinations or blond hair blue eyes combinations. Our kids may well have blond hair and brown eyes or black hair and blue eyes – new, unique combinations that are not like either myself or my spouse. In fact, if we both have a recessive red hair allele, we may end up with some kids with blue eyes and red hair or some other unique combination.
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