Rock, Paper, Scissors Investigating traits that are always seen when passed from parents to offspring

Transcription

1 Rock, Paper, Scissors Investigating traits that are always seen when passed from parents to offspring Objectives 1. Students will understand how some traits are always expressed when passed from parent to offspring. 2. Students will understand that some traits are not always expressed when passed from parent to offspring. 3. Students will be able to identify similarities and variations in physical traits expressed by offspring of a parent plant. Materials Rock, Paper, Scissors Recording Chart, one for each pair of students Plant Feature Page, one for each student Crayons and scissors for each student What Does It Look Like? activity sheet for each student 5 Gene Pool boxes made from shoe boxes (labeled leaves, fruit, flowers, roots, and stems) Background The Father of Genetics, Gregor Mendel, was born in He was born into a peasant family and later entered into a monastery in Brunn (a city in the southeastern part of the Czech Republic), where he received an education. The great work that Mendel did in the quiet monastery garden was ignored until after his death in His work marked the beginning of modern genetics. Mendel s major contribution was to demonstrate that inherited characteristics are carried as discrete units in each generation. These units came to be known as genes. Genes are the basic units capable of transmitting characteristics from one generation to the next. A trait becomes the genetically determined characteristic or quality that distinguishes one from another. When an offspring is formed, its traits are determined by a combination of genes from each parent. Each parent contributes one half of the genes for each trait. In the simplest cases, genes are either always expressed (dominant) or not always expressed (recessive). When a dominant gene combines with a recessive gene, the dominant gene s characteristics are expressed in the offspring. When two recessive genes are combined, the recessive characteristic is expressed in the offspring. Co-dominance occurs when the genes for a particular trait are equally strong. In this case, the two variations of the gene are expressed in equal strength (e.g., red vs. white= pink). Time: 90 minutes (can be split into two class periods) Grade: 5 Core Standard: V- Students will understand that traits are passed from the parent organisms to their offspring, and that sometimes the offspring may possess variations of these traits that may help or hinder survival in a given environment. Objective 1- Using supporting evidence, show that traits are transferred from a parent organism. Intended Learning Outcomes: Students will know and explain science information specified for the grade level; record data; describe or explain observations carefully and report with pictures; understand the nature of science; and cite examples of how science affects life. Gregor Mendel studied yellow and green pea plants to determine which traits were always expressed when passed from parent plants. 1

2 Mendel conducted his work with pea plants because they were readily available and easy to cultivate. Different varieties had different characteristics. He started with 32 types of pea plants which he studied for about two years. He wanted to see which characteristics were clearly defined. The results of these experiments were called dominant traits and recessive traits by Mendel. He continued with various experiments until his death in Mendel s work was first reported in 1865 to a small group of people at the Brunn Natural History Society. Sadly, no one seemed interested in what Mendel was talking about. It wasn t until 1900 that Mendel s work was discovered by three other scientists working independently of each other. Mendel s brilliant analysis of the questions they sought to answer, the design of his experiments, and the clarity of his results are so outstanding that his name is permanently linked with the first principles of genetics. In agriculture there are many examples of dominant, recessive and co-dominant traits. Many of the foods we enjoy every day have been bred to look, taste, grow and develop using the principles that Mendel first discovered. Some examples are listed. Perhaps you have noticed that the dominant-traited plants are easier to find in your grocery store. * Red potato skin is dominant over white potato skin. * Russet colored potato skin is dominant over white potato skin. * Green peas are dominant over yellow peas. * Red cherry tomatoes are dominant over yellow cherry tomatoes. * Red and white snapdragon flowers are co-dominant and produce pink flowers. * Short and tall corn plants are co-dominant and produce medium height corn plants. * Tall sunflower plants are dominant over short sunflower plants. * Yellow kerneled corn is dominant over white kerneled corn. Questions for Investigation or Assessment 1. Why would dominant traited plants be more readily available in the grocery store? What would a farmer need to do in order to grow a crop that exhibited only recessive traits? Do you think this would cost him more or less money? Activity Procedures 1. Have students list words that are associated with the words dominant (dominated, dominating, dominate, domain, dominance, predominant, dominator, etc.) and recessive (recessively, recede, receded, receding, recessional, recession, etc.). Then, discuss the differences between the concept of dominating a situation and receding in the same situation. For instance, if two people wanted to climb up the ladder of a slide at the same time, one person might dominate the situation by yelling it was his turn or pushing someone out of the way to go up first. Someone else might recede by walking away and playing something else. The receding person may play at the slide later when there is less competition (similar to genes!). Role play a few situations such as lining up after recess or participating in class discussions. 2. Describe the game Rock, Paper, Scissors using the words dominant and recessive. Discuss that rock dominates 2

3 scissors, scissors dominate paper and paper dominates rock. Have the students play this game with a partner, recording their outcomes on the Rock, Paper, Scissors Recording Chart. The outcome column will say either Rock, Paper, Scissors. If both people choose the same item then it is a tie and the item that both people chose will be written in the outcome box. The procedure for playing the game is described below. To Play Rock, Paper, Scissors: After a count of 1-2-3, each player must symbolize a rock, scissors or paper with one hand on a desk or table top. The hand symbol for rock is a fist. The hand symbol for scissors is the first two fingers cutting the air in a scissors motion. The hand symbol for paper is a flat hand on the desk top or table top. It is important that both players reveal their chosen hand symbols at exactly the same time. Teacher Notes: 3. Discuss the outcome of the game. Are there ways of making certain one person will always dominate (win)? 4. Discuss dominant and recessive in terms of genes and heredity using some of the ideas given in the background information. 5. Have each partnership color and cut out a Plant Feature Page. Place the features into the appropriate gene pool containers (shoe boxes) labeled Leaves, Fruit, Flowers, Roots or Stems. Each partnership will contribute a dominant and recessive trait for each feature. Place the five boxes in different locations throughout the room. 6. Hand out, to each pair of students, the What Does It Look Like? page. From the five separate gene pool containers have each student randomly select one feature. Have the students fill in the gene chart as each feature is chosen. The partners then need to determine what their plant looks like. For example, if one partner chooses a dominant round fruit and the other partner chooses a recessive oval fruit, the plant will have round fruit. Have the students complete their plant by drawing the appropriate features on their plant. 7. Have the students display their plants. Discuss how many dominant traits were expressed compared to recessive traits (students should easily see that there were more dominant traits 3

4 expressed than recessive traits). Discuss the wide variety of plants produced from the same gene pool and how this activity shows that it would be highly unlikely for two plants to be exactly alike. Impress upon students that it is because of dominant and recessive traits that certain characteristics may only appear in select generations (why a child may have blue eyes like their grandmother, but neither of the child s parents has blue eyes). Teacher Notes: Extensions/Adaptations/Integration 1. Have the students design their own dominant and recessive features for the gene pool, perhaps adding some co-dominant traits. Have them create the offspring with modeling clay. 2. Display pictures of parent plants along with four different pictures of possible offspring. Have the students select which offspring is most appropriate based upon a list of dominant and recessive traits given by the instructor. Students should be able to justify their answer. Additional Resources Lesson adapted from materials available from the California Agriculture in the Classroom. Visit their web site for more information: Materials Adapted by the, 4

5 Rock, Paper, Scissors Recording Chart Name Date Round Partner A Partner B Outcome (Rock, Paper, Scissors) Possible Outcomes: * Rock dominates scissors * Scissors dominates paper * Paper dominates rock 1) Which outcome was most common in your partnership? 2) Which outcome was the least common? 3) Were your results similar to the results of the class? 4) Describe one thing you learned about heredity by doing this activity. 5

6 What Does It Look Like? Name Date Complete this plant diagram by following the instructions of your teacher. Plant Diagram Features Partner A Partner B Outcome Leaf Fruit Flower Stem Root 6

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