cellular energetics

  • Metabolism: The sum of all chemical reactions that occur within a living organism to maintain life, including both anabolic (building up) and catabolic (breaking down) processes.

  • Autotroph: An organism that can produce its own food using light, water, carbon dioxide, or other chemicals; also known as a producer.

  • Heterotroph: An organism that cannot produce its own food and must obtain nutrients by consuming other organisms or organic matter; also known as a consumer.

  • ATP (Adenosine Triphosphate): The primary energy currency of the cell, a nucleotide that stores and releases chemical energy.

  • Enzyme: A biological catalyst, usually a protein, that speeds up chemical reactions by lowering the activation energy.

  • Activation Energy: The minimum amount of energy required to start a chemical reaction.

  • Cellular Respiration: A set of metabolic reactions occurring in cells to convert chemical energy from oxygen molecules or nutrients into adenosine triphosphate (ATP), and then release waste products.

  • Glycolysis: The first stage of cellular respiration, occurring in the cytoplasm, where glucose is broken down into pyruvate, producing a small amount of ATP and NADH.

  • Citric Acid Cycle (Krebs Cycle): The second stage of cellular respiration, occurring in the mitochondrial matrix, where pyruvate is further oxidized, generating CO2, ATP, NADH, and FADH2.

  • Electron Transport Chain (ETC): The final stage of cellular respiration, located in the inner mitochondrial membrane, where electrons are passed through a series of protein complexes, generating a proton gradient used to produce ATP.

  • Oxidative Phosphorylation: The process in cellular respiration where ATP is synthesized using the energy derived from the electron transport chain and the movement of protons across the mitochondrial membrane.

  • Fermentation: An anaerobic process that allows glycolysis to continue by regenerating NAD+ in the absence of oxygen; produces less ATP than cellular respiration.

  • Photosynthesis: The process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose or other organic molecules.

  • Light-Dependent Reactions: The first stage of photosynthesis, occurring in the thylakoid membranes, where light energy is absorbed and converted into chemical energy in the form of ATP and NADPH.

  • Calvin Cycle (Light-Independent Reactions): The second stage of photosynthesis, occurring in the stroma, where ATP and NADPH are used to fix carbon dioxide and synthesize glucose.

  • Chloroplast: An organelle found in plant and algal cells where photosynthesis takes place.

  • Mitochondria: An organelle found in eukaryotic cells that is the primary site of cellular respiration.

  • Anaerobic: Occurring in the absence of oxygen.

  • Aerobic: Occurring in the presence of oxygen