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Published byRalf George Modified over 9 years ago
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Who was Gregor Mendel (biographical information)? What did he study? Why did he use pea plants for his research? What were his results? What conclusions did he make (laws & rules) Why is his work important?
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Considered the “Father of Genetics” for his important discoveries Worked in the 1800’s in Austria; lived in a monastery Used pea plants to study Heredity
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Mendel used pea plants for his research because they are easy to grow, easy to pollinate, and they have distinctive, observable traits Mendel conducted Monohybrid crosses, in which he studied how one trait was inherited in pea plants He cross-pollinated parents with opposite characteristics (P 1 generation) He found that all of the offspring (F 1 generation) had the dominant trait When he crossed two F 1 plants to make the F 2 generation, he found that the traits always appeared in a 3:1 ratio
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Mendel also studied how two traits were inherited – he referred to these as Dihybrid crosses He found that when two heterozygous (hybrid) parents were crossed, the F2 generation showed a 9:3:3:1 ratio
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Mendel studied a variety of traits in pea plants for many years Based on his conclusions, he developed several rules and laws of genetics that are used today to understand heredity Although we now understand that there are many exceptions to Mendel’s rules, the heredity of many traits follows these patterns
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Rule of Unit Factors – each organism has two factors (genes) that control each trait - each different form of a gene is called an ALLELE - if an organism has two of the SAME allele, it is known as HOMOZYGOUS - if an organism has two DIFFERENT alleles, it is known as HETEROZYGOUS - the combination of alleles ( genes ) is known as the GENOTYPE, and the genotype determines the PHENOTYPE, which is the actual trait or appearance
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Rule of Dominance – the DOMINANT allele is the one that is observed (“stronger”), and the RECESSIVE allele is hidden Law of Segregation – the two alleles for each trait separate when gametes are formed during meiosis, so that a parent passes on only ONE allele at random for each trait Law of Independent Assortment – genes for different traits are inherited independently of one another; the genes you inherit for one trait do not influence your other traits
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