Cellular Processes, Genetics, and Enzyme Function

Photosynthesis

  • Definition: Photosynthesis is the metabolic process through which plants, algae, and certain bacteria convert radiant energy from sunlight into chemical energy stored as food.

  • Subcellular Site: Photosynthesis takes place inside specialized organelles called chloroplasts.

  • Reactants and Products:

    • Inputs (Reactants): Water and carbon dioxide, driven by sunlight absorption.
    • Outputs (Products): Glucose and oxygen.

  • Chemical Pathway Summary:

    • Water+Carbon Dioxide+Light Energy→Glucose+Oxygen\text{Water} + \text{Carbon Dioxide} + \text{Light Energy} \rightarrow \text{Glucose} + \text{Oxygen}

Cellular Respiration

  • Definition: Cellular respiration is the chemical process that breaks down glucose to produce biological energy stored in the form of Adenosine Triphosphate (ATP).

  • Aerobic Respiration:

    • Subcellular Site: Occurs within the mitochondria.
    • Oxygen Dependence: Requires the presence of oxygen.
    • Reaction Equation: Glucose+Oxygen→Carbon Dioxide+Water+36 ATP\text{Glucose} + \text{Oxygen} \rightarrow \text{Carbon Dioxide} + \text{Water} + 36\,\text{ATP}
    • Energy Output: Yields 36 ATP36\,\text{ATP} molecules per molecule of glucose processed.

  • Anaerobic Respiration:

    • Subcellular Site: Occurs within the cytoplasm.
    • Oxygen Dependence: Functions in the absence of oxygen.
    • Reaction Equation: Glucose→Lactic Acid+2 ATP\text{Glucose} \rightarrow \text{Lactic Acid} + 2\,\text{ATP}
    • Energy Output: Yields 2 ATP2\,\text{ATP} molecules per molecule of glucose processed.

DNA Replication and Mitosis

  • DNA Replication:

    • Prerequisite Timing: DNA replication must take place prior to cell division so that each newly generated cell inherits a complete and identical copy of the genetic makeup.
    • Structural Mechanism: The double-stranded DNA structure unzips to enable accurate copy generation.

  • Mitosis:

    • Definition: The cell division process that creates two genetically identical cells from a single original cell.
    • Biological Function: Serves specifically as the mechanism for cellular growth and tissue repair.

Enzymes

  • Definition: Enzymes function as biological catalysts within biological systems.

  • Primary Function: They significantly speed up the rate of chemical reactions.