Understanding Heredity. Part 1. 1. The work of gregor mendel. The Work of Gregor Mendel. ALL living things have a set of characteristics that are contained in genes. These genes come from our parents and are found in every cell in our body. Genetics – the scientific study of heredity.
The work of gregormendel
Why pea plants?
How did he make these monohybrid crosses?
What happened next?
Where did those traits go?
~ ¾ of the plants showed the traits of their parents (the F1 generation)
~ ¼ of the plants showed the traits of their grandparents (the P generation)
Homozygous – having 2 identical alleles
Heterozygous – having 2 different alleles
The phenotype of an organism is the result of:
Probability and Punnett Squares
½ x ½ x ½ = 1/8
ex. flower color
ex. flower color & plant height
Beyond Dominant & Recessive Alleles
1. Incomplete dominance – case where one allele is not completely dominant over another; produces an intermediate type
2. Codominance – both alleles contribute to the phenotype; it is a blend of the two alleles
3. Multiple Alleles – one individual can only have two alleles but more than two alleles can exist in a population.
4. Polygenic traits – many traits are produced by the interaction of several genes
Examples: hair, eye and skin color
5. The characteristics of an organism are also determined by the environment it lives in