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Chapter 9, Chapter 10 - Coggle Diagram

- - - - In alcohol fermentation, pyruvate is converted to ethanol (ethyl alcohol) in two steps. The first step releases CO2 from the pyruvate, which is converted to the two-carbon compound acetaldehyde. In the second step, acetaldehyde is reduced by NADH to ethanol.
      - During lactic acid fermentation, pyruvate is reduced directly by NADH to form lactate as an end product, regenerating NAD+ with no release of Co2. (Lactate is the ionized form of lactic acid.) Lactic acid fermentation by certain fungi and bacteria is used in the dairy industry to make cheese and yogurt.
- - - - These electron transfers are called oxidation-reduction reactions, or redox reactions for short. In a redox reaction, the loss of electrons from one substance is called oxidation, and the addition of electrons to another substance is known as reduction.
    - - The oxidation of methane by O2 is the main combustion reaction that occurs at the burner of a gas stove. The combustion of gasoline in an automobile engine is also a redox reaction; the energy released pushes the pistons. But the energy-yielding redox process of greatest interest to biologists is respiration: the oxidation of glucose and other molecules in food.
- - - - One of the first clues to the mechanism of photosynthesis came from the discovery that the O2 given off by plants is derived from H2O and not from Co2. The chloroplast splits water into hydrogen and oxygen atoms.
    - - During cellular respiration, energy is released from sugar when electrons associated with hydrogen are transported by carriers to oxygen, forming water as a by-product. The electrons lose potential energy as they “fall” down the electron transport chain toward electronegative oxygen, and the mitochondrion harnesses that energy to synthesize ATP