knowverseQuestion 1
What does metabolism include?
Metabolism refers to cellular chemical processes.
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This complex web of chemical changes that happen within a living organism is known as metabolism.
From the Knowverse course text.
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Energy transfer in cells
Metabolism includes the chemical reactions of a living cell. Those reactions transform matter and transfer energy rather than creating energy from nothing. Cells maintain organized structures by taking in energy and releasing heat and other products to their surroundings. Local order in an organism is compatible with increasing total entropy.
Enzymes speed reactions by lowering activation energy, the barrier a reaction must overcome. They do not supply the reaction's energy or get used up as fuel. ATP helps couple energy-releasing processes to cellular work. Hydrolysis converts ATP to ADP and phosphate, and cells use energy to regenerate ATP.
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This initial investment of energy required to start a reaction is known as activation energy. It acts as a barrier that prevents molecules from reacting randomly and keeps your body's structures stable.
From the Knowverse course text.
Fuel, oxygen and light
During glycolysis, glucose is split into smaller molecules, producing some ATP and loading electron carriers. In aerobic respiration, further reactions transfer electrons through a chain. Oxygen accepts electrons at the end. Energy from electron transfer helps establish an ion gradient, which ATP synthase uses to produce ATP.
Photosynthesis begins with light absorption by pigments such as chlorophyll. Light reactions produce ATP and electron carriers used in carbon fixation. The Calvin cycle builds organic molecules from carbon dioxide using those products. It does not directly capture light, but depends on the chemical supplies generated by the light reactions.
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The second stage is the Calvin cycle, which uses that stored energy to build organic molecules.
From the Knowverse course text.