Lesson 5 of 30
Objective: Students will be able to identify ATP as the energy unit of the cell and explain its role in the cycling of energy through the processes of photosynthesis and respiration.
Warm-Up: What do all living things require in order to function?
Ask the warm-up question as a lead into the content for the day and also as a review of concepts that have been covered in previous lessons. Allow 4-5 students to respond with their thoughts. Listen for students to indicate that energy is needed for living things to function. If students fail to point this out, make the point for the class. Remind students of GRACE, the characteristics of living things. Ask students, what letter of GRACE reflects that living things need energy? Listen for responses that indicate that they understand that the “E” represents energy, which is necessary for the work that is done in living things. Ask a second question, “What do we call the work of the body? “ Look for students to identify that metabolism is the work of the body and energy is required for metabolic processes.
As a formative assessment of how well students have retained information, ask students to name all 5 characteristics of living things. It’s helpful to periodically spiral back on previous concepts. If students can’t name the 5 characteristics of life, perform a brief review of each of the traits.
Introduce New Material
Inform students that today we will be talking about the energy currency that is needed of all organisms. Share the learning targets for the lesson so that students will know what it is that they should be able to do and know by the end of the lesson:
- I can explain the process of obtaining and utilizing energy within each group of organisms.
- I can explain the constant cycling of ATP-ADP.
Present the key vocabulary for this topic: heterotroph, chemical reaction, autotroph, adenosine triphosphate (ATP), adenosine diphosphate (ADP), hydrolysis, dehydration synthesis, chemical bond, cellular respiration, photosynthesis, currency, metabolism, energy, exergonic reaction, endergonic reaction. Instruct students to add the bold terms to their vocabulary maps. Maintain a practice of requiring student to maintain a record of vocabulary terms that contain either root words, prefixes or suffixes. Explicitly teaching vocabulary allows students to develop the ability to decipher new words based on their identification of root words, prefixes and suffixes. Reserve the explicit teaching of the words for the place in the lesson where they mentioned.
Project or write the term, adenosine triphosphate on the board. Ask students to tell what they can predict about the molecule based on its’ name. If necessary, cue students to direct their attention to the prefix “tri”. Listen to see if students make the connection that the molecule contains 3 phosphates. This type of prompting helps students learn how to use the practice of identifying the meaning of prefixes or suffixes to figure out the meaning of words. Explain that ATP is the high energy molecule of the cell.
Using an LCD projector, display an image of an ATP molecule. Label each of the parts of the ATP molecule and instruct students to do the same, using guided notes. Number each of the three major parts (sugar, adenosine and 3 phosphates) and point out each of the phosphate groups so that students gain an understanding of ATP’s molecular structure. Ask, “What do the lines between the phosphates represent?” Look for a response that indicates that the lines in the molecular structure represent chemical bonds. Explain that energy is stored in the bonds of the ATP molecule. Emphasize this point and check for understanding by repeatedly asking students to tell you where the energy is stored in an ATP molecule. Once you are sure that everyone knows that energy is stored in the chemical bonds of ATP, ask students to predict how the energy is released from the ATP molecule.
Do not expect to hear the correct response immediately. Before you answer the question, provide students a mental image that might help them draw the correct conclusion. In this case, use a mental image of a glow stick. Describe how a glow stick does not glow until it is snapped which causes the two chemicals inside to react and emit a glow. Use this imagery to help teach the term, exergonic reaction. Point out the connection between “ex” in exergonic and the word, exit. Ask students, “What is exiting when the glow stick is snapped?” Listen to a few student thoughts and clarify that energy is released when a glow stick is snapped. After providing students the glow stick metaphor for exergonic reactions, ask again, “How can energy be released from the ATP molecule?” At this point, most students will correctly state that a bond must to be broken to release energy. Point out the when the bond is broken and energy released, ATP is converted into ADP, adenosine diphosphate.
Follow the explicit teaching of the term exergonic with teaching the term, endergonic. Help students make the connection between “en” in endergonic and the words, ‘in or inside”.
Allow students to watch two short video clips, Energy and bonds and ATP-energy currency of the cell. Both these clips can be found on the Discovery education site, a great resource for science information. Before watching the video clips, remind students of the viewing expectations and prepare at least 1-2 questions or a task that students will complete after the video ends. For example when the clip ends ask students, “Is photosynthesis an endergonic or exergonic reaction?” Require students to defend and explain the rationale for their answer. Students should be able to identify that photosynthesis is an endergonic reaction because energy is stored.
Display a visual ATP diagram of the ATP-ADP cycle using a LCD projector.
Perform a “think aloud” as you explain what is occurring at each point in the diagram. The purpose of a think aloud is to allow students to hear and watch how you think to arrive at a correct response. Write on the diagram and narrate your thinking about what the diagram is showing and why you think so. Instruct students to write on their guided notes to emphasize the key points you have identified.
After performing the “think aloud”, demonstrate the ATP-ADP jar model and ask students to consider whether the top on the jar or off the jar represents the ATP molecule and why. Instruct students to discuss their thoughts with their seat partner. Remind them to use the content specific vocabulary in their explanations. As they are practicing sharing content knowledge with one another, walk around the room and listen for correct statements. If students share incorrect statements, use guiding questions, prompts or cues to help guide them to the necessary corrections of their own thinking.
Distribute markers and colored pencils. Instruct students to complete a thematic graphic organizer. The main topic is ATP, which should be centrally located on the page. Instruct students to write 5 factual statements about ATP around the central theme, ATP. Instruct them to display the information in any fashion they see fit, as long as the 5 points are related to ATP.
The three student work samples that are included demonstrate that students gained understanding about the concepts and that they were able to creatively display their understanding in three unique ways. Student 1 indicates accuracy of information in a different manner that student 2, which uses a dollar bill as the center of the organizer. The use of the dollar bill indicates that the student understands that ATP is the energy currency of the cell. Student 3 indicates a high level of understanding and use of academic vocabulary.
Engage students in a whole class discussion question, “How is a cell phone like an ATP molecule when its charged and like an ADP molecule when its dead and in need of a charge?”
As a formative assessment, look for students to be able to communicate that ATP is the usable energy molecule like a charged cell phone and ADP is the used energy molecule like a dead cell phone. If students are not able to easily convey this understanding, attempt to restate key concepts before students are dismissed and plan to revisit key concepts in the next class session.