Mendel & His Peas
Gregor Mendel – an Austrian monk, scientist, and gardener – was a keen observer of the world around him. Curious about heredity (how traits passed from one generation to the next), he grew and tested almost 30,000 pea plants.
During the 1850’s, Mendel studied genetics by doing controlled breeding experiments with pea plants. Pea plants were used because they reproduce quickly, have easily observed traits, and Mendel could control which pairs of plants reproduced. Mendel allowed one group of flowers to self-pollinate. Another group he cross-pollinated himself. Mendel cross-pollinated hundreds of plants for each set of traits – flower color, seed color, and seed shape. Mendel recorded the traits that appeared in the offspring.
A cross between true-breeding plants with purple flowers produced plants with only purple flowers. A cross between true-breeding white flowers produced plants with only white flowers. When Mendel crossed the true-breeding purple with true-breeding white flowers, all of the offspring had purple flowers. These offspring are called hybrids (different forms of the same gene – ex. Tt). When he crossed two hybrids, the trait that had disappeared in the 1st generation reappeared in the 2nd generation. After analyzing the result of his experiments, Mendel concluded that two genetic factors control each inherited trait. He proposed that the sperm and egg each contributed one factor for each trait.
Mendel also hypothesized that each hybrid had a dominant trait (a genetic factor that blocks another genetic factor) and a recessive trait (a genetic factor that is blocked by the presence of a dominant factor). Dominant traits are represented using capital letters and recessive traits are illustrated using lower case letters. A recessive trait is only observed when two recessive genetic factors are present in the offspring.
Today, Mendel is called the father of genetics (the study of how traits are passed from parents to offspring). After Mendel published his findings, however, his “laws of heredity” were ignored until the early 1900’s.
1-Pager Directions
Before reading article
1. Number paragraphs
2. Scan the text and circle any words that are unfamiliar, any words that seem important or any vocabulary words
Read the article
3. Circle any additional important or vocabulary words
4. Underline any important or main idea sentences (5 word limit)
After reading (each section below should be done in a different colored pencil)
5. Around the edge of the page, write all circled vocabulary words
6. In the top ¼ of the page, create a title based on the article (may not be the same as the article)
7. In the next ¼ of the page, draw a picture that represents what you read (or a piece of it)
8. Around each side and the bottom of the picture, do a mini boarder of vocabulary words that you had circled in the article. Use the most important words.
9. In the next ¼ of the page, copy the most important thing from the article. Make sure to use quotation marks.
10. In the last ¼ of the page, write a Higher Order Thinking Question about the article and answer it if you can.