Cellular Organelles and Biological Processes Explained
Cellular Organelles
- Mitochondria: Oval-shaped organelles with a double membrane. They provide the energy necessary for cell function.
- Vacuoles: Membranous vesicles that store water, reserve substances, or waste products.
- Lysosomes: Membranous vesicles that break down complex substances into simpler molecules for cellular use.
- Cytoskeleton: A network of filaments distributed throughout the cytoplasm. It forms the cell's skeleton and facilitates movement.
- Centrioles: Two hollow cylinders formed by filaments that direct the movement of the cytoskeleton.
- Golgi Apparatus: Stacks of flattened membranous sacs surrounded by vesicles. It packages substances manufactured in the reticulum and manages cellular secretion.
- Endoplasmic Reticulum: A network of sacs and canals extending through the cytoplasm, involved in the synthesis of proteins and lipids.
- Rough ER: Features ribosomes attached to the outer membrane.
- Smooth ER: Lacks attached ribosomes.
- Ribosomes: Small particles found free in the cytoplasm or attached to the endoplasmic reticulum; they are responsible for protein synthesis.
Cellular Transport Mechanisms
- Diffusion: A mechanism where small molecules cross the plasma membrane. If the concentration is lower inside the cell than in the extracellular medium, molecules enter the cell.
- Osmosis: A specific form of diffusion involving the movement of water through a membrane from a dilute solution to a more concentrated one.
Endocytosis and Exocytosis
- Endocytosis: The process by which large particles that cannot penetrate the membrane enter the cell.
- Exocytosis: The process by which large particles are expelled from the cell.
Metabolic Processes
- Catabolism: A set of reactions that degrade complex molecules into simpler ones to release energy.
- Anabolism: A set of reactions focused on building complex molecules from simpler ones.