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TITLE: How Cells Duplicate and Why Where Something Can Go Wrong AUTHOR: Judy A. Grunke GRADE LEVEL/SUBJECT: 7; Life Science (2-week unit) OVERVIEW: Cells are the basic unit of function and structure in living things. After students have learned cell parts and organization, they are introduced to cell division. Understanding the role of deoxyribonucleic acid (DNA), and how and why it must replicate, is essential to comprehending how our genetic patterns are transmitted to new cells. Constructing a three-dimensional model of the DNA molecule enhances the students' discernment. PURPOSE: Genes are the small heredity units on chromosomes and are made of DNA molecules. Before a cell divides, the DNA must replicate so that the two new cells will each have the organism's genetic code. If foreign materials invade the cell while the DNA is duplicating, they may be incorporated into the molecule. If these miscoded cells are not killed by the body's own defense systems, they will multiply and could take over, disrupting the cell's normal activities or dividing rapidly and erratically, crowding out the normal cells. It is important to understand the construction of the DNA molecules; how and why they divide; how good nutrition and personal habits can help maintain the genetic code. OBJECTIVE(s): 1. The learner will be able to define pertinent vocabulary. 2. The learner will be able to describe the DNA molecule, its construction, how it replicates. 3. The learner will be able to discuss why good nutrition is essential for proper DNA duplication. 4. The learner will be able to explain how, when, a carcinogen may be incorporated into the DNA molecule. 5. The learner will demonstrate his/her understanding of the DNA molecule by constructing one from chenille pieces. RESOURCES/MATERIALS: Provided: textbook, paper, pencils, (colored pencils are excellent) Needed: Film: "The Intricate Cell", American Cancer Society, Boise, ID For Lab: 6 pieces chenille per student (2 the same color, 1 each of 4 different colors) wire cutters or sharp scissors ACTIVITIES AND PROCEDURES: SET Models of a cell undergoing mitosis. A model of a DNA molecule. INSTRUCTIONAL INPUT VOCABULARY: deoxyribonucleic acid, DNA, gene, chromosome, replicate, mitosis, nutrients, carcinogen REVIEW: Nutrients, food containing them. Protein contains nitrogen, an essential ingredient in the DNA molecule. Mitosis--interphase, when the DNA replicates. DISCUSS: How DNA molecules are constructed; when and how the DNA molecule makes a copy. FILM: "The Intricate Cell" Observe cells undergoing mitosis and the construction of DNA molecules. Discuss the causes of 80% of cancers--industrial pollutants, overexposure to the sun, cigarette smoke. Discern how and when cancer-causing agents can disrupt DNA's replication. GUIDED PRACTICE TEXTBOOK: vocabulary and study questions CLASS NOTES LAB: Construct a DNA molecule INDEPENDENT PRACTICE Quiz, Text TYING IT ALL TOGETHER: Deoxyribonucleic acid (DNA) is the molecule which contains our genetic codes. The DNA must copy itself before the cell divides so the daughter cells will get the code. The cell has to have the proper nutrients in the right amounts so that the DNA can replicate. If carcinogens are in the cells when the DNA is duplicating, they may be incorporated into the DNA molecule. Cigarette smoke contains known cancer-causing materials. We have control over 80% of known carcinogens.
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