2.7 Cells use ATP molecules to get energy.
Cells need energy for many functions. The source of energy is ATP (adenosine triphosphate).
•ATP undergoes a chemical reaction that releases energy.
ATP + H2O → ADP + P + energy
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UNIT 1 Concept 2.7Chapter 2: The Cell Up Close: Processes That Sustain Life
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UNIT 1
19. What does ATP stand for, and what type of molecule is it?
20. How is ATP used in cells?
21. Describe the reaction in which ATP releases energy.
Concept 2.7Chapter 2: The Cell Up Close: Processes That Sustain Life
Pause and Check
2.8 Cellular respiration makes ATP.
Aerobic cellular respiration is one way plant and animal cells make ATP. The overall process is
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UNIT 1 Concept 2.8Chapter 2: The Cell Up Close: Processes That Sustain Life
The numerous reactions involved occur in two stages:
1. Glycolysis, which takes place in the cytosol.
2. Oxidative respiration, which takes place in
mitochondria.
Glycolysis
• occurs in the cytosol
• involves many reactions that o split each glucose molecule into two 3-carbon
molecules (pyruvate) o form 2 molecules of ATP
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UNIT 1 Concept 2.8Chapter 2: The Cell Up Close: Processes That Sustain Life
Oxidative Respiration
• Pyruvate from glycolysis enters the mitochondrion.
• A series of chemical reactions involving oxygen break pyruvate down to carbon dioxide and water.
• As many as 34 ATP molecules can be produced for each
glucose molecule.
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UNIT 1 Concept 2.8Chapter 2: The Cell Up Close: Processes That Sustain Life
Overall process of aerobic cellular respiration
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UNIT 1 Concept 2.8Chapter 2: The Cell Up Close: Processes That Sustain Life
Food Molecules and the Production of ATP
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UNIT 1 Concept 2.8Chapter 2: The Cell Up Close: Processes That Sustain Life
Cellular Respiration and Photosynthesis
• Some organisms, such as plants, produce their own food by photosynthesis.
• Photosynthesis takes place in chloroplasts and involves using energy from the Sun to convert carbon dioxide and water into glucose and oxygen.
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UNIT 1 Concept 2.8Chapter 2: The Cell Up Close: Processes That Sustain Life
Plants also use oxygen to make ATP by aerobic cellular respiration, but they produce more oxygen than they use.
Fermentation
• Some organisms can survive where there is little or no oxygen. • Fermentation is the production of ATP in the absence of oxygen. • Glycolysis produces two pyruvates from each glucose molecule.
Then reactions such as alcoholic fermentation or lactic acid fermentation produce ATP.
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UNIT 1 Concept 2.8Chapter 2: The Cell Up Close: Processes That Sustain Life
This is how alcohol is made – yeast ferment the wheat, grapes etc.
This what your muscles do if you exercise too strenuously.
