California Agriculture in the Classroom

Use of Biotechnology in Selecting the Right Plants

Grade Level(s)

6 - 8

Estimated Time

50 minutes

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.

Materials

For each student:

Essential Files (maps, charts, pictures, or documents)

Essential Links

Vocabulary

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

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

chromosome: rod or thread-like structures found in cell nuclei; contains the DNA molecules that make up the chromosome’s genes

deoxyribonucleic acid (DNA): chemical that makes up genes (the information molecules for the cell); looks like a spiral ladder, with sugar and phosphate groups as the ladder sides and the four bases (adenine, cytosine, guanine and thymine) as the rungs

biotechnology: techniques that collectively allow the precise identification, isolation, alteration, and re-introduction of heritable traits to living organisms for specific purposes

protein: molecule composed of a chain of many amino acids that acquires a particular folded shape due to the amino acid sequence; both the amino acid sequences and the pattern of folding are involved in the specific functions of the protein

restriction enzyme: enzyme that will cut DNA molecules only at sites where particular sequences of base pairs occur

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:

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.

Interest Approach – Engagement

  1. 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.
  2. Ask your students what type of characteristics they like in a strawberry. List characteristics such as sweetness, flavor, size, etc.
  3. 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. 
  4. 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.

Procedures

  1. 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.
  2. Show YouTube Video, DNA Extraction and Marker Assisted Selection to explain the process of genetic markers. 
  3. 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.
  4. Distribute the Super Strawberries student activity handout and review each section. Do one example with the class.
  5. 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.

Concept Elaboration and Evaluation

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

Enriching Activities

Suggested Companion Resources

Sources/Credits

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

Author(s)

Mandy Garner

Organization Affiliation

California Foundation for Agriculture in the Classroom