Use of Biotechnology in Selecting the Right Plants

Grade Level

6 - 8

Purpose

Students will simulate how a type of biotechnology called Marker Assisted Selection (MAS) is used to identify crop plants that have desirable traits such as sweet tasting fruit or natural resistance to a pest or disease. Grades 6-8

Estimated Time

50 minutes

Vocabulary

amino acid: biochemical units from which all proteins are made; twenty different amino acids occur most commonly in the proteins of all life forms

base: one of four different chemical units comprises DNA or RNA which codes for the amino acid sequence of proteins, four bases are adenine, cytosine, guanine, and thymine, uracil substitutes for thymine in RNA

base pair: two complementary bases on opposing strands of the sugarphosphate ladder structure of DNA

biotechnology: the use of living systems and organisms to develop or modify products or processes

chromosome: a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes

deoxyribonucleic acid (DNA): deoxyribonucleic acid; a self-replicating material present in nearly all living organisms as the main constituent of chromosomes; the carrier of genetic information

enzyme: protein catalyst, which speeds up a specific chemical reaction

genetic code: groups of three nucleotide bases (codons) which specify a particular amino acid

marker assisted selection (MAS): indirect selection process that is not selected based on the trait we observe but rather on the genetic markers that will bind to the genes that code for the trait we are looking for

protein: an essential nutrient responsible for building tissue, cells, and muscle

restriction enzyme: DNA-cutting enzymes that recognize one or a few target sequences and cuts DNA at or near those sequences

Background Agricultural Connections

This lesson is part of the From Genes to Jeans II series which was written to encourage students to hone basic genetic concepts and skills through defined vocabulary, and provided explanations all the while applying the terms to agricultural concepts used in the industry. Other related lessons and activities include:

Applying Heredity Concepts
Use of Biotechnology in Selecting the Right Plants
Enhancing Our World Research Project and Presentation

You may like to review the following information with students prior to beginning the activity.

Chromosomes are long molecules of DNA that store genetic information. In eukaryotic organisms like humans, chromosomes are stored inside the cell nucleus where the DNA is tightly coiled around proteins called histones. This enables the DNA to fit inside the tiny space of the cell. If removed from the cell nucleus and uncoiled, human DNA would stretch as long as six feet.

Traits are controlled by pieces of DNA called genes. These genes are located on chromosomes. Humans have 46 chromosomes, and scientists have identified which genes are coded for at certain locations on different chromosomes.

Genes are specific sequences of DNA that are located on chromosomes. Genes are similar to instructions that tell a cell how to make one particular protein, when to make it, how much to make, and where it should be made. Proteins are molecules that are involved in every aspect of our body’s structure and function. For example, melanin is a pigment which gives skin its color. Melanin is a protein. Insulin is a hormone that regulates blood sugar levels. Insulin is a protein.

DNA is a long molecule made up of units called nucleotides. Each nucleotide is made up of three parts: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base (Adenine, Thymine, Cytosine, and Guanine. Adenine always pairs with Thymine and Guanine always pairs with Cytosine in DNA. In the genetic code, each group of three bases A,T,G,C (Adenine, Thymine, Guanine, Cytosine) codes for a specific amino acid. Example, AGC codes for the amino acid serine. Chains of amino acids form the structure of proteins.

Engage

Ask your students to brainstorm everything they know about strawberries. List facts on the board as students brainstorm. Use further guided questions to help them identify how strawberries are grown, that they are a fruit, their nutritional value, etc. Use the attached Strawberry Commodity Fact Sheet for more information.
Ask your students what type of characteristics they like in a strawberry. List characteristics such as sweetness, flavor, size, etc.
Ask students if they were a strawberry farmer, what type of characteristics they would like in a strawberry. Strawberry farmers are looking for the same characteristics as consumers, however, they are also interested in choosing a variety of berry that is resistant to diseases or pests and that has an adequate shelf life.
With this basic introduction to strawberries, students are now prepared to learn about specific DNA markers in strawberries and how science and agriculture work together to produce strawberries and other foods.

Explore and Explain

Ask students to write down 20 nucleotide bases using the symbols A,T,G,C in any order. Next have them switch with a partner and have their partner write the complementary base strand below the original strand.
Show YouTube Video, DNA Extraction and Marker Assisted Selection to explain the process of genetic markers.
Discuss how scientists can build genetic markers in the lab that have complementary base pairs to genes that they are interested in identifying in plants. Fluorescent green protein is added to these markers so they light up and glow green when they find and adhere to the gene of interest. Markers can be added to cells on a microscope slide or to extracted DNA on a microscope slide. If the DNA from the cells glows green, then the plant has the gene that the scientist is looking for. This will help scientists quickly identify which plants they want to select for breeding.
Distribute the Super Strawberries student activity handout and review each section. Do one example with the class.
After students complete the activity, have students draw each strawberry, color, and label its characteristics. Have students circulate through the room in small groups to view the class drawings and discuss why they think MAS technology is important for our future. Have each group share their thoughts with the class.

Evaluate

At the completion of this activity, summarize and review the following key concepts:

Farmers use their knowledge of science and biological processes to determine the best varieties of plants to grow.
Scientists help select and promote desirable traits in crops (such as strawberries) by using knowledge of genetics and heredity.
Using advanced science and biology in the production of our food enables farmers to provide enough food for a growing population.

Acknowledgements

The development of this lesson was funded in 2014 by Monsanto Fund to provide teachers with lessons in science and biotechnology that meet Common Core and Next Generation Science Standards

Executive Director: Judy Culbertson
Layout and Design: Nina Danner

Recommended Companion Resources

Author

Mandy Garner

Organization

California Foundation for Agriculture in the Classroom