cellstructure

Cell structure refers to the organization of components within a cell that support its growth, metabolism, and reproduction. All cells share a plasma membrane that encloses the cytoplasm, a cytosol containing dissolved enzymes and nutrients, and genetic material. In all cells, ribosomes synthesize proteins from mRNA, and most cells maintain a selectively permeable boundary that regulates exchange with the environment.

In prokaryotes, DNA is in a single circular chromosome located in a nucleoid region; cells lack a true nucleus and most membrane-bound organelles. They typically have a cell wall, ribosomes, a plasma membrane, and sometimes external structures such as flagella or pili.

Eukaryotic cells have a nucleus that houses DNA and is separated from the cytoplasm by the nuclear envelope. They contain membrane-bound organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, and in plants and algae chloroplasts. The cytoskeleton provides shape and tracks for transport.

Plant and algal cells add chloroplasts for photosynthesis, a rigid cell wall, and a large central vacuole. Animal cells generally lack cell walls and chloroplasts and rely on the extracellular matrix and organelles for functions.

Materials are organized and transported via vesicular trafficking and membrane transport proteins. The plasma membrane maintains homeostasis through diffusion, osmosis, and active transport; organelles specialize in metabolism, protein synthesis, and waste processing.