Cell Organelles and Their Functions

Organelle Overview

• Nucleus: Variable location within the cell; stores genetic material (DNA) and nucleoli; key for RNA synthesis and ribosomal subunit assembly.
• Ribosomes: Found in the cytoplasm; crucial site for protein synthesis from amino acids.
• Rough endoplasmic reticulum (rough ER): Located in the cytoplasm with ribosomes attached; primarily responsible for synthesizing proteins.

Membrane-bound Organelles

• Smooth endoplasmic reticulum (smooth ER): Present in the cytoplasm; involved in lipid synthesis and detoxification processes.
• Golgi apparatus: Situated in the cytoplasm; modifies proteins received from the rough ER and packages them into secretory vesicles.
• Secretory vesicle: In cytoplasm; transports materials produced by the cell, created from the Golgi apparatus, and released via exocytosis.
• Lysosome: Located in the cytoplasm; contains digestive enzymes that break down materials entering the cell; also formed by the Golgi apparatus.
• Peroxisome: Found in the cytoplasm; responsible for breaking down fatty acids, amino acids, and hydrogen peroxide.

Energy Production and Structure

• Mitochondrion: Located in the cytoplasm; major site of aerobic respiration and ATP synthesis, essential for cellular energy.
• Microtubule: Supports the cytoplasm; aids in cell division and forms structural components of cilia and flagella.
• Centrioles: Found in the cytoplasm; play a vital role in chromosome movement during cell division.

Cellular Projections

• Cilia: Located on cell surface, typically numerous; help in moving substances over cell surfaces.
• Flagella: Present on sperm cells, usually one per cell; facilitate propulsion of sperm cells.
• Microvilli: Extensions of cell surfaces, abundant on certain cells; increase surface area for absorption and secretion.