Biology Forums - Study Force

Explain Gregor Mendel's pea experiments and how he leads to the discovery of genetics. Why and how can we predict our genes? Use 5-7 scientific vocabulary words.

Gregor Mendel's pea experiments were a series of breeding experiments that he conducted in the mid-19th century. Mendel chose pea plants (Pisum sativum) for his experiments because they have easily observable traits and can self-fertilize or cross-fertilize with controlled breeding. He focused on seven distinct traits, such as seed color, flower color, and plant height. Mendel's experimental process involved cross-pollinating pea plants with different traits. For example, he would cross-pollinate a tall plant with a short plant. He then collected the seeds produced from these crosses and grew them to observe the characteristics of the offspring, known as the F1 generation. In Mendel's experiments, he found that all the offspring in the F1 generation displayed the same trait as one of the parents. In the case of the tall and short plant cross, all the offspring were tall. This led Mendel to conclude that there must be dominant and recessive traits.

Mendel then allowed the F1 generation to self-pollinate, resulting in the F2 generation. In the F2 generation, Mendel observed that both the dominant and recessive traits reappeared, with a ratio of approximately 3:1. This observation led him to propose the concept of "dominant" and "recessive" traits. From these experiments, Mendel formulated three fundamental laws of inheritance: Law of Segregation: Each individual has two copies of a gene, known as alleles, which separate during the formation of sex cells (gametes). Thus, each gamete carries only one allele for a particular trait. Law of Independent Assortment: The inheritance of one trait is independent of the inheritance of other traits. In other words, the segregation of one gene does not influence the segregation of another gene. Law of Dominance: In a pair of alleles for a given trait, one allele may be dominant and express itself in the organism's appearance (phenotype), while the other allele may be recessive and remain hidden in the presence of the dominant allele.

Some human traits, but not all, are Mendelian. When we say that some traits are Mendelian, it means that these traits follow Mendel's principles of inheritance and can be explained by his laws. Mendelian traits are those that are controlled by a single gene and are inherited in a predictable manner from one generation to the next. Thus, we can to some extent predict whether or not our offspring will have certain traits if we know for certain that the trait is Mendelian, and we know the alleles of both parents. Some examples of Mendelian traits include a widow's peak, the ability to role one's tongue rolling, and attached vs. free earlobes.