Overview
This lecture introduces the cell, its key functions, and basic structures, emphasizing how these components support life processes and maintain homeostasis.
Major Functions of the Cell
- Cells perform metabolism, including both building (anabolic) and breaking down (catabolic) reactions.
- Cells carry out transport across the membrane and within the cell to move substances.
- Cellular communication occurs both inside the cell and with other cells, using chemical and electrical signals.
- Cells grow and divide for development, repair, and reproduction.
- Reproduction involves cell division: mitosis for growth/repair, and meiosis for sexual reproduction (covered later).
Types of Metabolic Reactions
- Anabolic reactions synthesize macromolecules like proteins, lipids, and DNA.
- Catabolic reactions break down molecules for reuse or energy.
- Oxidation-reduction reactions involve electron transfer, important in energy production.
Basic Cell Structure
- The plasma membrane separates the cell’s interior (intracellular) from the external environment (extracellular).
- Cytoplasm consists of cytosol (fluid) and dissolved substances such as electrolytes and nutrients.
- Organelles are specialized structures within cytoplasm, each performing specific functions.
- The cytoskeleton (microtubules, microfilaments, intermediate filaments) provides shape, structure, and tracks for intracellular transport.
- The nucleus is a membrane-bound control center containing DNA and nuclear pores for exchange with cytoplasm.
Specialization and Diversity
- Cells vary in structure/organelles based on their function (e.g., liver cells have more lysosomes, muscle cells more mitochondria).
- All cells contain the same DNA, but different genes are expressed according to their specialized roles.
Key Terms & Definitions
- Metabolism — all chemical reactions in the cell, including anabolism and catabolism.
- Anabolic reaction — builds larger molecules from smaller units.
- Catabolic reaction — breaks down molecules to release energy or reuse components.
- Plasma membrane — outer boundary regulating entry and exit of substances.
- Cytoplasm — fluid inside the cell containing organelles and solutes.
- Organelle — specialized structure within a cell performing a specific function.
- Cytoskeleton — network of protein filaments providing structural support and transport paths.
- Nucleus — membrane-bound organelle housing DNA and managing genetic information.
Action Items / Next Steps
- Review cell organelles and their functions from previous anatomy or biology courses.
- Prepare for the next lecture on plasma membrane structure and transport mechanisms.