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Science 7 Standard 4 08-06 8/22/02 7:49 AM Page 143 Standard Indicator 7.4.5 How a Cell Works Purpose Students will explain that the basic function of organisms, such as extracting energy from food and getting rid of wastes, are carried out within the cell and understand that the way in which cells function is similar in all organisms. Materials English/ Language Arts Have students write narratives explaining their journeys through a cell on a typical day. Instruct them to include the functions of organelles in their stories. extending THE Activity A. Pre-Activity Preparation Have a stovetop available or use beakers and hot plates to prepare the gelatin and boil spaghetti until it is just pliable. B. Pre-Activity Discussion 1. Ask students: “What are the basic functions of organisms?” 2. Discuss students’ responses; be sure to discuss how organisms consume food for energy, reproduce, get rid of wastes, grow, etc. 3. Explain to students that the basic functions of an organism take place at a cellular level. Explain that organisms are made up of cells and that although not all cells are exactly the same (e.g., muscle cells and skin cells), they all carry out basic functions necessary for an organism to survive. C. Animal Cells and Plant Cells 1. Distribute a copy of the BLM Cell Diagrams to each student and show the transparency of the BLM. 2. Explain that even though most cells are microscopic, many contain many tiny parts called organelles. (continued) Standard 4 / Activity 3 Indiana Science Grade 7 Curriculum Framework, October 2002 curriculum ACTIVITY Explain the function of the liver and ask students which of the organelles studied might be present in large quantities in liver cells [lysosomes]. Relate the functions of other organs to the number of organelles present (e.g., mitochondria in muscle cells). Standards Links 7.4.1, 7.4.4, 7.4.8, 7.7.2 page 143 Standard 4 For the teacher: transparency of Black Line Master (BLM) Cell Diagrams, overhead projector, hot plate and beakers or stovetop and pan For each student: copy of BLMs Cell Diagrams and Gelatin Cells For each group of students: sparkling grape gelatin mix and water [cytoplasm], plastic bag [cell membrane], plastic container with lid [cell wall], small plum [nucleus], mandarin orange slices [mitochondria], green grapes [chloroplasts], dried apricots [Golgi complex], half-cooked spaghetti [smooth and rough endoplasmic reticulum], poppy seeds [for surface of rough endoplasmic reticulum], red grape [lysosome], small balloon [vacuole], toothpick connecting across the Science 7 Standard 4 08-06 8/22/02 7:49 AM Page 144 Activity (continued) 3. Use the overhead to explain how each organelle has a specific function. 4. Explain that animal cells and plant cells are similar since they both have organelles, which carry out similar functions. 5. Explain that there are also differences between plant and animal cells (e.g., plant cells have cells walls and chloroplasts, which allow them to make their own food through photosynthesis). Standard 4 D. Activity 1. Acknowledge that although they are viewing two-dimensional models of cells, cells are actually three-dimensional. 2. Divide students into groups and distribute a copy of the BLM Gelatin Cells to each group. Direct half of the students to build a plant cell model and half to build an animal cell model. 3. Distribute the materials listed on the BLM Gelatin Cells and direct students to use the BLM Cell Diagrams to build models. 4. Monitor students as they work. Ask questions, such as: Which materials could represent each part of the cell in your model? [gelatin/cytoplasm, plastic container/cell wall, plastic bag/cell membrane, green grape/chloroplast, etc.] Which organelle is responsible for extracting energy from foods for cell work? [mitochondria] Which is responsible for getting rid of wastes? [lysosomes] What makes all cells similar? What makes them different from each other? [All cells carry out some basic functions, but there are specialized cells in different parts of an organism that perform specialized functions.] 5. After the gelatin sets in the refrigerator and the cells are complete, have students retrieve their cells and examine them. 6. Ask students questions such as: “Do all of the ‘cells’ have the same shape?” [Compare how the animal cells vary in shape, but plant cells do not vary as much since they were surrounded by a rigid cell wall.] Classroom Assessment Basic Concepts and Processes At the end of the activity, ask questions, such as the following: How are the basic functions of an organism carried out at the cellular level? How do all cells function similarly? What might happen if a number of organelles in a cell did not function properly? Give an example. How can you tell a plant cell from an animal cell? page 144 Standard 4 / Activity 3 Indiana Science Grade 7 Curriculum Framework, October 2002 Science 7 Standard 4 08-06 8/22/02 7:49 AM Page 145 Name: Cell Diagrams Animal Plant cell membrane mitochondrion smooth endoplasmic reticulum cell membrane cell wall mitochondrion nucleus central vacuole golgi apparatus smooth endoplasmic reticulum lysosome nucleus golgi apparatus rough endoplasmic reticulum chloroplast rough endoplasmic reticulum Each organelle has a specific job, such as the following: Nucleus, “The Control Center”: stores genetic information which has directions for cell division, the production of proteins, etc. Lysosomes, “The Garbage Disposal”: found in animal cells; breaks down and excretes cell wastes Mitochondria, “The Power House”: respiration takes place here; food energy is converted into chemical energy for the cell to work Smooth Endoplasmic Reticulum: makes substances such as fats and steroids Rough Endoplasmic Reticulum: makes proteins, which get changed and packaged for specific jobs in the Golgi Apparatus (or Golgi Body) Central Vacuole: found in plant cells; stores wastes and water (central vacuoles store cellular products, food, and waste in most types of cells) Chloroplast: not found in animal or fungal cells; where photosynthesis takes place Organelles are held in place by cytoplasm, and cells are enclosed by membranes which allow certain substances to enter and leave. Plant (and fungal) cells have a second covering called a cell wall, which makes the cells rigid. Standard 4 / Activity 3 Indiana Science Grade 7 Curriculum Framework, October 2002 Black Line Master 1 page 145 Science 7 Standard 4 08-06 8/22/02 7:49 AM Page 146 Cell Diagrams Teacher Directions Make a transparency copy of the BLM Cell Diagrams. In addition, make a photocopy of the BLM Cell Diagrams for each student. Distribute a copy of the BLM to each student and show the transparency, explaining the functions of each organelle. Answer Key Not applicable. Black Line Master 1 page 146 Standard 4 / Activity 3 Indiana Science Grade 7 Curriculum Framework, October 2002 Science 7 Standard 4 08-06 8/22/02 7:49 AM Page 147 Name: Gelatin Cells Create a Cell Model Materials: Sparkling grape gelatin mix, water, plastic bag, twist tie, large mixing bowl, spoon, plastic container with lid, mandarin orange slices, plums, green grapes, dried apricots, half-cooked spaghetti, poppy seeds, red grapes, small balloon, toothpick Plans for creating your model: 1. Will you create a plant or animal cell model? 2. Which organelles/cell parts will you need to represent in your plant or animal cell model? 3. Which materials listed best represent each organelle and cell part? Procedure: 1. Write your names on the plastic bag. 2. Boil water and follow directions on the package to make the gelatin. 3. Fill the plastic bag with gelatin and the organelles. 4. Seal the bag with a twist tie. 5. If you are making a plant cell model, place the bag into a plastic container and seal the lid. Then, stack your model with other plant cell models in the refrigerator for the gelatin to harden. 6. If you are making an animal cell model, stack your model with other animal cell models in the refrigerator for the gelatin to harden. 7. When the gelatin has set, remove your cell from the refrigerator and compare it with the rest of the class cells. Standard 4 / Activity 3 Indiana Science Grade 7 Curriculum Framework, October 2002 Black Line Master 2 page 147 Science 7 Standard 4 08-06 8/22/02 7:49 AM Page 148 Gelatin Cells Teacher Directions Distribute a copy of the BLM Gelatin Cells to each group of students. Direct half of the students to create a plant cell model and the other half to create an animal cell model. Distribute the materials listed on the BLM and direct students to decide which materials should represent each part of the cell model. Answer Key Below are the suggested materials to represent different organelles: sparkling grape gelatin [cytoplasm] plastic bag [cell membrane] plastic container with lid [cell wall] small plum [nucleus] mandarin orange slices [mitochondria] green grapes [chloroplasts] dried apricots stuck together with a toothpick [Golgi complex] half-cooked spaghetti [smooth endoplasmic reticulum] half-cooked spaghetti with poppy seeds [rough endoplasmic reticulum] red grape [lysosome] small inflated balloon [vacuole] Black Line Master 2 page 148 Standard 4 / Activity 3 Indiana Science Grade 7 Curriculum Framework, October 2002