Qwiz5 Quizbowl Essentials – Gregor Mendel

With an epithet like The Father of Genetics, Gregor Mendel might evoke images of a scientist in a lab coat presiding over a crowded laboratory. However, this picture fails to square with Mendel’s actual life. Although he was a towering intellect, Mendel was known in his lifetime primarily as a shy and unassuming Augustinian monk with a green thumb. It was his exacting botanical experiments, carried out in the garden and not the lab, that ensured his reputation would live on long after his death in 1884. Let’s explore some of Mendel’s work in today’s Qwiz5!

By analyzing questions, you can see patterns emerge, patterns that will help you answer questions. Qwiz5 is all about those patterns. In each installment of Qwiz5, we take an answer line and look at its five most common clues. Here we explore five clues that will help you answer a tossup on Gregor Mendel.

EXPERIMENTS ON PLANT HYBRIDIZATION

Mendel did not set out to create an entirely new branch of scientific inquiry. His initial ambitions were to raise hybrid pisum sativum (pea plants) and document their characteristics. It was during these experiments, however, that Mendel discovered the heredity of certain pea plant characteristics, such as color, height, and seed texture. When Mendel’s paper, Experiments on Plant Hybridization, was presented in 1866 to the Natural History Society of Brünn, the importance of the findings was not immediately realized. Retrospectively, however, the report has been recognized as a foundational text of genetics.

DOMINANT AND RECESSIVE TRAITS

Mendelian inheritance, an idea developed from Mendel’s paper, proposed the existence of dominant vs. recessive traits. Mendel postulated that offspring receive two versions of a gene, otherwise known as alleles - one from each parent. When the alleles are different, one of them may express itself more strongly than the other. This allele codes for a dominant trait. The allele that is masked is called recessive. This theory differed from what was the dominant theory of the time, blending inheritance, which suggested that offspring inherited a “blend” of their parents’ traits.

SEGREGATION AND INDEPENDENT ASSORTMENT

The laws of Segregation and Independent Assortment are the two foundational laws of Mendelian inheritance. The law of segregation describes how only one out of two of the gene copies for a particular trait are placed in a gamete (sperm or egg cell). This means that an offspring’s traits are determined by the combination of parental gametes. The second law of Mendelian inheritance, independent assortment, describes how different alleles for different genes are transmitted independently of each other.

R.A. FISHER

Mendel’s findings have been questioned by some. The British geneticist Ronald Fisher was one of the most prominent of these critics. In 1936 Fisher applied statistical methods, specifically a Pearson’s chi-squared test, to the data Mendel published in Experiments on Plant Hybridization. Fisher claimed that Mendel’s findings were too perfect, and in his paper he alleged that Mendel may have fudged the data to support his conclusions. However, other geneticists have gone on to question Fisher and support the veracity of Mendel’s data.

CARL CORRENS & HUGO DE VRIES

Two botanists played an important role in publicizing Mendel’s findings. While working at the University of Tübingen, botany tutor Carl Correns discovered Mendel’s work and restated his laws of independent assortment and segregation. Hugo de Vries, a botany professor at the University of Amsterdam, experimented with plant hybridization at the turn of the 20th century and independently reached the same conclusions as Mendel. These discoveries brought new attention to Mendel’s research.

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Quizbowl is about learning, not rote memorization, so we encourage you to use this as a springboard for further reading rather than as an endpoint. Here are a few things to check out:

• Will scientists ever be able to put the Mendel-Fisher controversy to bed? Not likely.
  

• For an overview of Mendel’s initial experiments with pea plants, check out this article.
  

• Sometimes a visual can help make sense of Mendelian laws. Watch a video explanation here.

• Blended inheritance wasn’t the only proposed explanation for heredity that Mendel’s work debunked. Check out the notion of pangenesis here!

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