# Gregor Mendel's Experiments with Pea Plants --- **Gregor Mendel** is calld **The Father of Genetics** for a reason. He essentially invented the field of [[genetics]] with his groundbreaking experiments on pea plants, and discovered how [[trait|traits]] get passed down to offspring through [[gene|genes]]. His research fundamentally altered our understanding of herdidty and, ultimately, led to the discovery of [[chromosome|chromosomes]]. **Gregor Mendel's experiments with pea plants** were not only the product of many years of hard work and meticulous recordkeeping, but also sheer luck in picking the right plants and keen insights. ## Why Peas? **Peas** were the ideal plant for Mendel to work with. Not only were they small, hardy, easy to grow and could move quickly though generations, but they were also highly cultivated by humans. In Europe at the time there were 10-12 differen strands, all of them were "pure lines", or homozygous for their particular traits. In other words, every pea plant *always produced the same thing*. Of course, in complex organisms like humans, not having a genetic diversity is a bad thing, but for peas—and indeed for Mendel—it was very bennifical. >[!experiments] Smart *and* Lucky Mendel was undoubtedly very smart and hard working, but he was also indredably lucky that he found his particular pea plants. For example: >- The [[trait|traits]] he was working with were 7 out of 7 all located on different chromosomes. (What's more is these peas only have 7 chromosomes total!) >- The traits all showed [[dominance and recession|complete dominance and recession]]. >- The traits were all [[trait|discrete]]. None of the traits were the product of multiple genes [[gene|interacting]]. ![[colorful beans.png]] ## The Experiment ### F1 In the **first generation**, Mendel performed many reciprocal **monohybrid** male/female crosses, by carefully controling what pollen went where. Without fail, and regardless of which sex did what, the (what we now call) dominant trait was expressed. Of course, we now understand that although the [[genotype and phenotype|phenotype]] was all the same, there was indeed variety in the [[genotype and phenotype|genotype]]. Most importantly, from two [[allele|homozygous]] parents, we now had a completely [[allele|heterozygous]] generation of offspring. ### F2 In the **second generation**, Medel crossed the F1 generation with themselves, and had some, perhaps counterintuitve results. Without fail, the dominant and recessive traits appeared at about a 3:1 ratio. #### Punnett Square Analysis We can use **punnett squares** to analyze the possible gametes and their interactions will occur. ![[punnett square.png]] ### The Testcrosses The **testcross** was Menedel's way of checking himself. To prove his hypothesis about the genetic information being carried on a "particle", he crossed his F2 generation with a homozygous recessive pure line, and (correctly) anticipated the results. ___