Cell structure

Cell structure refers to the parts that make up a cell and the jobs they perform. A eukaryotic cell — the kind found in plants, animals, fungi and protists — is a highly organised unit in which different tasks are carried out by distinct compartments called organelles. Understanding these components and how they fit together is the foundation for studying how cells, and therefore whole organisms, function.

The cell is bounded by the cell membrane, a thin layer that controls the passage of substances into and out of the cell. Inside, the cytoplasm is a watery medium that holds the organelles and is the site of many chemical reactions. The nucleus is usually the largest organelle and contains the cell's DNA, which directs the production of proteins and the cell's overall activity. Mitochondria release energy from nutrients, supplying the cell with usable chemical energy.

Protein production involves several structures working together: ribosomes assemble proteins, the endoplasmic reticulum transports and processes them, and the Golgi apparatus modifies and packages them for use or export. Vesicles and vacuoles store and move materials within the cell. Plant cells include extra features absent from animal cells: a rigid cell wall outside the membrane for support, a large central vacuole, and chloroplasts containing the green pigment chlorophyll, where photosynthesis takes place. Together these structures allow the cell to grow, respond and reproduce.

Frequently asked questions

What is an organelle?

An organelle is a specialised structure inside a cell that carries out a particular function, such as the nucleus storing DNA or mitochondria releasing energy.

Where are proteins made in the cell?

Proteins are assembled by ribosomes, then processed by the endoplasmic reticulum and packaged by the Golgi apparatus.

What is the role of the cell membrane?

The cell membrane surrounds the cell and controls which substances can enter or leave, helping maintain the right internal conditions.