Cell Structure & Function Cheat Sheet

A printable reference covering cell types, organelles, membranes, transport, surface area to volume ratio, and microscopy scale for grades 9-10.

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Cell structure and function explains how cells are organized and how each part helps the cell stay alive. This cheat sheet helps students compare prokaryotic and eukaryotic cells, identify major organelles, and connect structure to function. It also supports quick review of cell size, microscopy scale, and the big idea that cells are the basic unit of life. The most important concepts include the role of the cell membrane, the difference between plant and animal cells, and how organelles work together. Students should know that the nucleus stores DNA, ribosomes build proteins, mitochondria release usable energy, and chloroplasts perform photosynthesis in plants. Transport rules such as diffusion, osmosis, and active transport explain how materials move across membranes.

Key Facts

All living things are made of one or more cells, and the cell is the basic unit of structure and function in organisms.
Prokaryotic cells do not have a nucleus or membrane-bound organelles, while eukaryotic cells do have a nucleus and membrane-bound organelles.
The cell membrane is selectively permeable, meaning it allows some substances to pass through more easily than others.
Diffusion moves particles from high concentration to low concentration without using cellular energy.
Osmosis is the diffusion of water across a selectively permeable membrane from high water concentration to low water concentration.
Active transport moves substances from low concentration to high concentration and requires energy, usually ATP.
Surface area to volume ratio can be written as SA:V = surface area / volume, and smaller cells usually exchange materials more efficiently.
The mitochondria release energy from food during cellular respiration, summarized as glucose + oxygen -> carbon dioxide + water + ATP.

Vocabulary

Organelle: A specialized structure inside a cell that performs a specific job.
Nucleus: The membrane-bound organelle in eukaryotic cells that contains DNA and controls many cell activities.
Cell membrane: A flexible barrier around the cell that controls what enters and leaves.
Cytoplasm: The jellylike material inside the cell where organelles are located and many chemical reactions occur.
Ribosome: A small cell structure that builds proteins from amino acids.
Chloroplast: A plant and algae organelle that uses light energy to make glucose during photosynthesis.

Common Mistakes to Avoid

Confusing prokaryotic cells with eukaryotic cells is wrong because prokaryotes lack a nucleus and membrane-bound organelles, while eukaryotes have them.
Saying only animal cells have mitochondria is wrong because both plant and animal cells use mitochondria for cellular respiration.
Mixing up diffusion and active transport is wrong because diffusion moves down a concentration gradient without energy, while active transport moves against the gradient using energy.
Calling the cell wall the same as the cell membrane is wrong because the cell wall provides rigid support, while the membrane controls movement into and out of the cell.
Forgetting that structure matches function is wrong because organelles have shapes and features that help them perform specific jobs, such as folded mitochondrial membranes increasing reaction surface area.

Practice Questions

1 A cube-shaped cell has a surface area of 54 square micrometers and a volume of 27 cubic micrometers. What is its surface area to volume ratio?
2 A microscope image is 40 mm wide, and the real cell is 0.04 mm wide. What is the magnification?
3 A plant cell is placed in a solution with a lower water concentration than the inside of the cell. In which direction will water move by osmosis?
4 Explain why a cell with many mitochondria is likely to need a large amount of energy.