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8.1 Energy and Life
Describe the role of ATP in cellular activities.
Explain where plants get the energy they need to produce food.
Chemical Energy and ATP Energy is the ability to do work. Organisms need energy to stay alive.
Adenosine triphosphate (ATP) is a chemical compound cells use to store and release energy.
· An ATP molecule consists of adenine, the sugar ribose, and three phosphate groups.
· Cells store energy by adding a phosphate group to adenosine diphosphate (ADP) molecules.
· Cells release energy from ATP molecules by subtracting a phosphate group.
Energy provided by ATP is used in active transport, to contract muscles, to make proteins, and in many other ways.
Cells contain only a small amount of ATP at any one time. They regenerate it from ADP as they need it, using energy stored in food.
Heterotrophs and Autotrophs The energy to make ATP from ADP comes from food. Organisms get food in one of two ways.
Heterotrophs get food by consuming (eating) other organisms.
Autotrophs use the energy in sunlight to make their own food.
Photosynthesis is the process that uses light energy to produce food molecules.
Chemical Energy and ATP
For Questions 1–6, complete each statement by writing the correct word or words.
1. is the ability to do work.
2. The main chemical compound cells use for energy is (ATP).
3. is a 5-carbon sugar molecule that is part of an ATP molecule.
4. The of ATP are the key to its ability to store and supply energy.
5. ATP releases energy when it bonds between its phosphate groups.
6. Most cells only store enough ATP for of activity.
Name Class Date
7. Label each part of the diagram of an ATP molecule below.
For Questions 8–10, refer to the Visual Analogy comparing ATP to a charged battery.
8. In the visual analogy, what chemical is represented by the low battery?...