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This overview explores Mendel’s principles of inheritance, focusing on his First Law (Law of Segregation) and Second Law (Law of Independent Assortment). It highlights how gene segregation occurs during meiosis, leading to the probability of offspring traits. The discussion expands beyond Mendel to cover incomplete dominance, co-dominance, multiple alleles, polygenic traits, and epistasis. It raises questions about advancements in DNA technology since 1979 and how they may impact our understanding of genetic inheritance.
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Patterns of Inheritance Ch. 10
Mendel’s Laws • Mendel’s First Law: The Law of Segregation • The two copies of a gene separate during meiosis and end up in different gametes. • This begins to show the probability of offspring. • Can be shown via Punnett square
Mendel’s Laws • Mendel’s Second Law: The Law of Independent Assortment • When gametes form, the separation of the 2 copies of one gene during meiosis is independent and separate from each other gene
Beyond Mendel • Mendel’s results with his pea plants showed complete dominance • This pattern is not always the case. • We also have incomplete dominance, co-dominance, multiple allele traits, polygenic traits, and epistatic genes, for starters.
Incomplete Dominance • Formation of a new phenotype in heterozygotes that appears as an intermediate of the two original phenotypes. • Red + white = pink flowers
Co-Dominance • The formation of a new phenotype that appears in the heterozygote that is a combination of the two original phenotypes • Red + white = red with white spots in flowers
Multiple Allele • There are more than 2 alleles present within a population. It is the combination of the alleles present that give you your phenotype. • Hair color in rabbits. Several types.
Polygenic Traits • Traits that are distinguished by multiple genes on the genome • Skin color in humans
Reading Questions • This was finalized in 1979. There have been many advancements in DNA technology since then. How could these advancements change the results? Is there cause to look at them again? What else could be done to prove or disprove the connection? • There are instances when mutations occur that could change the genotype of the offspring quite a bit from the parents. Provide 1 piece of evidence from the reading to show this is NOT the case.