Cell Components
Middle School
Definition
The internal structures of a cell, each with a specific role. The nucleus controls the cell's activities, the cytoplasm holds the contents, and the cell membrane controls what enters and leaves; plant cells also have a wall and chloroplasts.
Worked examples
An animal cell has a nucleus (control center), cytoplasm (jelly-like filling), and cell membrane (gatekeeper).
These three components work together to keep the cell alive and functioning.
A plant cell has all animal-cell parts plus a rigid cell wall (outer armor) and chloroplasts (food factories).
The wall provides structure and chloroplasts perform photosynthesis to make glucose.
Common mistakes
- The cell membrane is only in animal cells → Both plant and animal cells have a cell membrane Plant cells have both a membrane (inside) and a cell wall (outside).
- The nucleus holds the cytoplasm → The cytoplasm surrounds the nucleus and other organelles The nucleus floats inside the cytoplasm, not the other way around.
- Chloroplasts control what enters and leaves the cell → The cell membrane controls what enters and leaves Chloroplasts make food through photosynthesis; the membrane is the gatekeeper.
Where you'll use it next
You'll use cell components when studying specialized organelles like mitochondria and ribosomes, comparing prokaryotic and eukaryotic cells, and understanding how cells perform life processes in biology and health science.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026