The Structure and Function of Cells Cells are the smallest living units with a cell membrane, cytoplasm, and DNA. Eukaryotic cells have organelles like the nucleus, endoplasmic reticulum (ER), Golgi apparatus, vacuoles, mitochondria, chloroplasts (in plants), and a cell wall (in plants). Prokaryotic cells lack a nucleus or membrane-enclosed organelles but contain genetic material.
Organelles in Cell Functions Nucleus is the control center containing DNA; ribosomes synthesize proteins; ER transports materials synthesized by ribosomes; Golgi body customizes proteins for use; vacuoles store materials such as water in plant cells and lysosomes break down cellular debris. Mitochondria produce energy through cellular respiration while cytoskeleton maintains cell shape. Chloroplasts perform photosynthesis only in plant cells. Some unique structures include cilia for trapping particles and flagella for movement.