Mendelian Genetics, Scientific Paper

3075 Words13 Pages
Examining Mendel’s “First Law”: Observing Anthocyanin in Brassica rapa

Abstract

The foundation of genetics lies with the principles that Gregor Mendel outlined after his experiments with pea plants where he discovered the relationship between physical characteristics, or phenotype, and genetic traits, or genotype. This experiment aimed to reproduce Mendel’s results with the Brassica rapa plant, noted for it’s fast generation time, and anthocyanin, a purple pigment that can be visually tracked through subsequent generations. It is important for experiments resulting in scientific discovery to be replicable and peer reviewed. Since Mendelian genetics are the foundation of scientific education, including answering questions about
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Other forms of the genotype, (ygr/ YGR) and (YGR/YGR) will result in green leaves. A third gene in Brassica rapa is the rosette mutant, homozygous recessive. The genotype needed for the short, rosette plant form is (ros/ros). The other two genotypes (ros/ROS) and wild type (ROS/ROS) will result in the normal form of the plant. The phenotypes and genotypes are related in that the phenotypes provide a visible indication of the genotype. This is true in an individual with a homozygous recessive gene. However, in the case of dominant genes, since only one copy is needed for the phenotype to be present, then the second copy is not indicated. The second copy can be identified process where two individuals (P1 and P2) with the same dominant phenotype, called the parental generation, are bred. This produces an F1 or first generation of offspring. The F1 generation can also be bred and produce an F2 generation. Each individual in the F1 and F2 generations receives one copy from each parent of the 3-letter genotype code, called an allele.
Gregor Mendel theorized that certain combinations of alleles in a genotype would result in a specific ratio of phenotypes expressed in each generation. For example, in the case of the dominant heterozygous anthocyanin genotype, the P1 with (ANL/anl) crossed with the P2 (ANL/anl) would result in a 1:2:1 ratio for genotypes (ANL/ANL), (ANL/anl) and (anl/anl). However,
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