Bacteria are single-celled microorganisms that belong to the prokaryotic domain, lacking a true nucleus and membrane-bound organelles. They come in various shapes (spherical, rod-shaped, spiral) and sizes. Despite their simplicity, bacteria are remarkably diverse and ubiquitous in nature, thriving in various environments, including soil, water, and the human body. Key characteristics of bacteria include: Cell Structure: Lack a nucleus and membrane-bound organelles, have a cell wall for struct...