Biology Chapter 14 Objectives

Biology Chapter 14 Objectives - Chapter 14 Mendel and the...

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Chapter 14 Mendel and the Gene Idea Gregor Mendel’s Discoveries 1. Mendel’s particulate mechanism differed from the blending theory of inheritance, since it is the gene idea. According to his model, parents pass on discrete heritable units, genes, that retain their separate identities in offspring. This is different from the blending hypothesis, which is the idea that genetic material contributed by the two parents mix. 2. True-breeding refers to plants that produce offspring of the same variety when they self-pollinate. Hybridization is the mating or crossing of two true-breeding varieties. A monohybrid cross crosses two organisms that are heterozygous with respect to a single gene off interest. The P generation is the true-breeding parents, which are the parental generation. The F 1 generation, the first filial generation, is the hybrid offspring, and allowing the F 1 hybrids to self-pollinate produces an F2 generation, the second filial generation. 3. There are four components of Mendel’s hypothesis that led him to deduce the law of segregation. First, alternative versions of genes account for variations in inherited characters. The alterative versions of a gene are now called alleles. Second, for each character, an organism inherits two alleles, one from each parent. Each somatic cell in a diploid organism has two sets of chromosomes, one set inherited from each parent. Thus, a genetic locus is actually represented twice in a diploid cell. Third, if the two alleles at a locus differ, then one, the dominant allele, determines the organism’s appearance; the other, the recessive allele, has no noticeable effect on the organism’s appearance. The final part of Mendel’s model, now known as the law of segregation, states that the two alleles for a heritable character separate during gamete formation and end up in different gametes. Thus, an egg or a sperm gets only of the two alleles that are present in the somatic cells of the organism. This segregation corresponds to the distribution of homologous chromosomes to different gametes in meiosis. 5.
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This note was uploaded on 08/29/2009 for the course BIOL 101 taught by Professor Sakji during the Fall '08 term at Linn Tech.

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Biology Chapter 14 Objectives - Chapter 14 Mendel and the...

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