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Structure of a Cell

A cell has a basic plan with an outer boundary, living cytoplasm, and genetic material, arranged differently in different types of cells.

In one line: Every cell has a boundary and living contents; only eukaryotes have a true nucleus.

Practice This Concept

Understand it

In many eukaryotic cells, the cell membrane surrounds cytoplasm and a well-defined nucleus. Plant cells also have a cell wall outside the membrane. Prokaryotic cells do not have a true membrane-bound nucleus, while eukaryotic cells have a nucleus and membrane-bound organelles.

Example

An onion peel cell has a cell wall, cell membrane, cytoplasm, and nucleus, while a bacterial cell has genetic material without a true nucleus.

Rule to remember

Basic cell plan: boundary + cytoplasm + genetic material.

Plant cells have cell wall outside the plasma membrane; animal cells do not.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

If a diagram shows a nucleus, mitochondria, and cell membrane but no cell wall, identify it as a eukaryotic animal cell rather than a plant cell.

Method you can reuse

Look for cell wall, then check for a true nucleus, then identify organelles, then decide whether the cell is plant, animal, prokaryotic, or eukaryotic.

Sketch it in your answer

Use separate labelled diagrams of a plant cell, animal cell, and simple prokaryotic cell to show nucleus and cell wall differences.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

What is the main difference between prokaryotic and eukaryotic cells?

Think first, then show answer

Prokaryotic cells lack a true membrane-bound nucleus, while eukaryotic cells have a well-defined nucleus and usually membrane-bound organelles.

Common wrong answer

Calling a bacterial cell eukaryotic because it has DNA is wrong; the key point is whether the DNA is enclosed in a true nucleus.

Don't mix this up

Students often write that every cell has a cell wall, but animal cells do not have a cell wall.

Exam tip

For comparison questions, write the common parts first and then clearly separate plant, animal, prokaryotic, and eukaryotic features.