James P Hughes PhD

OBJECTIVES

■ To introduce cellular metabolism and the role of ATP as energy currency

■ To describe anaerobic and aerobic cellular respiration

■ To present the conversion of light energy to chemical energy in photosynthesis

■ To illustrate carbohydrate synthesis in different plants

OUTLINE

5.1 Metabolism and ATP 106

5.2 Anaerobic Cellular Respiration 107

5.3 Aerobic Cellular Respiration 114

5.4 Photosynthesis 126

5.5 Carbohydrate Synthesis 136

The conversion of energy is a feature of life, where photosynthesis and cellular respiration are complementary processes. Plants use the energy of sunlight via photosynthesis to produce biomolecules, which in turn are converted into energy via cellular respiration by all organisms. Understanding of how biological systems produce and utilize energy is helpful for development of novel power and transportation systems and other biology-based technologies that can be applied in medicine and environmental protection plans.

On a sunny day, your brain sends electric signals to your facial muscles with the result that they contract and make you smile. Your facial muscles can contract because they contain chemical energy, which they now convert into mechanical work and heat. The energy of the muscle is derived from the energy of your food, either a plant or an animal that had eaten a plant. The plant has received its energy by converting solar energy into chemical energy in form of carbohydrate molecules. Life, as we know it, is a constant transfer of energy from one system to another. It is the objective of this chapter to introduce the energy transfer in animal and plant cells.

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