What Are the Parts of a Cell and What Do They Do?

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1. 01

   Split cells into two types before learning any parts

   Prokaryotic cells, such as bacteria, have no nucleus and no membrane-bound organelles; their DNA sits loose in the cytoplasm. Eukaryotic cells — animal, plant, fungal — have both. Almost every comparison question rests on this division, and learning organelles without it produces answers that apply the wrong list to the wrong cell.

2. 02

   Learn what every cell has first

   A cell membrane, cytoplasm, ribosomes and genetic material appear in all cells, prokaryotic and eukaryotic alike. Starting with the shared four gives the rest of the topic a structure, because everything after this point is a difference rather than a new list to memorise.

3. 03

   Attach each organelle to a job, not a shape

   Diagrams reward recognition, exams reward function. The reliable way to hold the organelles is as a sentence about what the cell would lose without each one — no mitochondria means no usable energy, no ribosomes means no proteins. Recalling a function is also what earns the mark, since the question rarely asks only for a name.

4. 04

   Learn the plant additions as a set of three

   Plant cells contain everything an animal cell does plus three structures: a cellulose cell wall, chloroplasts, and a large permanent central vacuole. Grouping them as one set of three is more reliable than trying to recall a full list twice, and comparison questions are almost always asking about these three.

5. 05

   Test yourself by removing one organelle

   Ask what would fail if a given organelle stopped working, and the function becomes something you can reason out rather than recall. A cell without a nucleus cannot make new proteins because the instructions are gone; a plant cell without a vacuole wilts because it loses the internal pressure holding it firm.

01

The organelles and what each one does

This is the core list, and it is short enough to hold properly rather than approximately. Each entry pairs a structure with the single job it does, which is the form an exam answer needs to take.

Two of them are frequently confused. The cell membrane is partially permeable and present in every cell; the cell wall is rigid, made of cellulose in plants, and present only in plant, fungal and bacterial cells. A cell wall does not control what enters and leaves — the membrane inside it does.

• Nucleus — contains the DNA and controls the cell's activities
• Cytoplasm — the fluid where most chemical reactions take place
• Cell membrane — partially permeable; controls what enters and leaves
• Mitochondria — release energy through aerobic respiration
• Ribosomes — build proteins from amino acids
• Rough endoplasmic reticulum — studded with ribosomes; processes and transports proteins
• Smooth endoplasmic reticulum — makes lipids and detoxifies substances
• Golgi apparatus — modifies, sorts and packages proteins and lipids for delivery
• Lysosomes — contain digestive enzymes that break down waste and worn-out parts

02

Plant cells and animal cells

Every structure in an animal cell is also in a plant cell. The comparison question is therefore always in one direction: what does a plant cell have in addition?

The three additions each have a clear purpose. The cell wall is made of cellulose and gives the cell its shape and strength. Chloroplasts contain chlorophyll and carry out photosynthesis, which is why they are absent from root cells that never see light. The large permanent vacuole is filled with cell sap and keeps the cell turgid — when it loses water the plant wilts, which is the pressure being lost.

• Cell wall — cellulose, rigid, gives shape and support
• Chloroplasts — contain chlorophyll, site of photosynthesis
• Permanent vacuole — filled with cell sap, maintains turgor pressure

03

Bacterial cells are built differently

A bacterial cell has a cell wall, a cell membrane, cytoplasm and ribosomes, but no nucleus and no mitochondria or chloroplasts. Its genetic material is a single loop of DNA in the cytoplasm, often with small extra rings called plasmids alongside it.

Size is part of the comparison and is worth stating. Prokaryotic cells are typically a few micrometres across; eukaryotic cells are commonly ten to a hundred times larger by diameter. Questions asking for two differences will accept the absence of a nucleus and the difference in size, but the DNA point is the more precise answer.

04

How we teach this

We teach organelles by function first and by diagram second, because the diagram is what a student can recognise and the function is what the mark scheme asks for. A student who can label a cell and cannot say what the Golgi apparatus does has learned the less useful half.

The removal question — what fails if this stops working — is used throughout our science lessons. It turns a list into a set of consequences, and a student who has reasoned it out once rarely needs to revise it again.