Mendelian Genetics: Its Behavior on Two Diffeent Genes for Chlorophyll Production in Tobacco(Nicotiana Tabacum) Seeds Essay Example
Abstract
According to Mendel¡¦s Law of Segregation, phenotypic ratios may be influenced by dominance of one allele compared to another. When an organism produces its gametes by meiosis, the alleles separate. This is Mendel¡¦s First Law-the Law of Segregation. This experiment investigated the effects of complete and incomplete dominance on the behavior of two different genes for chlorophyll production in tobacco. Two sets of approximately 50-100 tobacco seeds were planted for one week. The plants were the F2 result of two sets of monohybrid F1 crosses Gg x Gg and CyCg x CyCg. A chromosome for these plants has two sets of genes. The gene at one locus has two alleles that code for normal chlorophyll production. Dominant allele represented as G produce the green phenotype. The mutant allele, g, produces no chlorophyll producing an albino phenotype. Therefore genotypes GG and Gg phenotypically are green. When mutant allele g is homozygous for it, gg, no chlorophyll is present and the plants phenotypically are albino. Therefore an expected phenotypic ratio would be 3:1. Another gene at a different locus also affects chlorophyll production. This gene also has two sets of alleles, but in this case the mutant of this allele, Cy, exhibits incomplete dominance with the other. Genotype CgCg is phenotypically green. Genotype CyCy is phenotypically yellow and genotype CyCg is phenotypically green-yellow. This would suggest a phenotypic ratio of 1:2:1. In the F2 generation of the first set, Gg x Gg, green plant color was observed more than the albino color. In the F2 generation of the second set, CyCg x CyCg, green and green-yellow were noticed more than yellow. The observations made suggest that in the first set of F1generation the null hypothesis cannot be rejected. As for observations for the second set of F1 generation, the null hypothesis can be rejected.
Introduction
Gregor Mendel pioneered modern genetics. His most famous analyses were based on clear-cut
According to Mendel¡¦s Law of Segregation, phenotypic ratios may be influenced by dominance of one allele compared to another. When an organism produces its gametes by meiosis, the alleles separate. This is Mendel¡¦s First Law-the Law of Segregation. This experiment investigated the effects of complete and incomplete dominance on the behavior of two different genes for chlorophyll production in tobacco. Two sets of approximately 50-100 tobacco seeds were planted for one week. The plants were the F2 result of two sets of monohybrid F1 crosses Gg x Gg and CyCg x CyCg. A chromosome for these plants has two sets of genes. The gene at one locus has two alleles that code for normal chlorophyll production. Dominant allele represented as G produce the green phenotype. The mutant allele, g, produces no chlorophyll producing an albino phenotype. Therefore genotypes GG and Gg phenotypically are green. When mutant allele g is homozygous for it, gg, no chlorophyll is present and the plants phenotypically are albino. Therefore an expected phenotypic ratio would be 3:1. Another gene at a different locus also affects chlorophyll production. This gene also has two sets of alleles, but in this case the mutant of this allele, Cy, exhibits incomplete dominance with the other. Genotype CgCg is phenotypically green. Genotype CyCy is phenotypically yellow and genotype CyCg is phenotypically green-yellow. This would suggest a phenotypic ratio of 1:2:1. In the F2 generation of the first set, Gg x Gg, green plant color was observed more than the albino color. In the F2 generation of the second set, CyCg x CyCg, green and green-yellow were noticed more than yellow. The observations made suggest that in the first set of F1generation the null hypothesis cannot be rejected. As for observations for the second set of F1 generation, the null hypothesis can be rejected.
Introduction
Gregor Mendel pioneered modern genetics. His most famous analyses were based on clear-cut