2.7 Cells use ATP molecules to get energy. Cells need energy for many functions. The source of...

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

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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.