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Cell Biology: an interactive cell biology course

Published 8 Nov 20265 min read

Cell Biology is an interactive cell biology course that tours the cell and explains how it lives, feeds and divides. Its 25 short sections cover cell theory and sizes, the parts of animal, plant and bacterial cells, how proteins are made, the cell membrane, diffusion, osmosis and active transport, surface area to volume, respiration, the nucleus, the cell cycle and mitosis, photosynthesis, specialised cells and stem cells.

It opens with an explorer of animal, plant and bacterial cells where each part lights up and says what it does, then every section zooms into one part of that picture.

What the course covers

Sections	Topic	What you do
1 to 3	What a cell is, cell theory and sizes	Put cells and their parts in size order across units
4 to 6	Inside an animal cell, and making proteins	Tap an organelle from its name or its job
7 to 10	The membrane, diffusion, osmosis and why cells stay small	Work out the surface area to volume ratio of a cube-shaped cell
11 to 12	Active transport	Sort examples into diffusion, osmosis and active transport
13 to 14	Respiration in mitochondria	Balance the respiration equation
15 to 18	The nucleus, the cell cycle and mitosis	Name the stage of mitosis from a picture
19 to 22	Plant, animal and bacterial cells, and photosynthesis	Tick which cells have each part, then build the word equations
23 to 25	Specialised cells and stem cells	Match each cell to the feature that suits its job

Parts of the cell

Animal cells have a nucleus holding the DNA, cytoplasm where most reactions happen, a membrane controlling what enters and leaves, mitochondria for respiration and ribosomes for making proteins. Plant cells add a cellulose cell wall, a permanent vacuole and chloroplasts; bacterial cells have no nucleus, with their DNA in a loop in the cytoplasm.

Moving substances

Diffusion moves particles from high to low concentration with no energy from the cell; osmosis is the same for water across a partially permeable membrane; active transport uses energy to move particles the other way, against the gradient. Our what is osmosis guide covers osmosis in depth.

Energy and division

Respiration in the mitochondria releases energy from glucose; photosynthesis in the chloroplasts makes glucose from light. Cells copy themselves through the cell cycle and mitosis, then specialise for jobs, while stem cells stay ready to become many types. See our mitosis and specialised cells guides for more.

Try a question from the course

Small cells have more surface for their size, so substances reach every part quickly. For a cube-shaped cell 2 µm on each side, the surface area is 6 × 2 × 2 = 24 µm² and the volume is 2 × 2 × 2 = 8 µm³, a ratio of 24 : 8 = 3 : 1. Double the side to 4 µm and the ratio falls to 96 : 64 = 1.5 : 1.

Now work out the ratio for a new cell, then press Mark to check your answer in the course.

Press Mark to have your answer marked in the Cell Biology course.

Who this course is for

GCSE biology students revising cell structure, transport, respiration, mitosis and specialised cells.
A-level and other advanced students who want the basics rock solid before going further.
Anyone who wants to understand the living units their body is built from.

What you need to know first

Nothing beyond basic science. Size conversions between millimetres, micrometres and nanometres, and the surface area of a cube, use simple maths that the course explains.

How long it takes

There are 25 sections and most take a few minutes. Learners without a plan can open two sections of a course a day, in order, so the whole course takes 13 days. A plan removes the daily limit and lets you go straight to any topic, such as active transport or mitosis.

Guided courseGenetics & DNAGo inside the nucleus: DNA, protein synthesis, inheritance and gene editing.

Common questions

Is this cell biology course free?

You can take every section without paying, two sections a day, in order. A plan removes the daily limit and opens any section straight away.

What are the main parts of an animal cell?

The nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cell wall, a permanent vacuole and chloroplasts.

What is the difference between diffusion, osmosis and active transport?

In diffusion, particles spread out from where they are crowded to where they are sparse. Osmosis is the same thing happening to water through a partially permeable membrane. Active transport moves particles from low to high concentration and needs energy from respiration.

What are the stages of mitosis?

Prophase, metaphase, anaphase and telophase, followed by the cytoplasm dividing. The result is two cells with the same chromosomes as the parent.

How are bacterial cells different from animal and plant cells?

Bacterial cells are prokaryotic: they have no nucleus, their DNA is a loop in the cytoplasm, often with small rings called plasmids, and they are much smaller.

Why are cells so small?

As a cell gets bigger, its volume grows faster than its surface area, so its membrane cannot take in substances fast enough for everything inside. Small cells have a high surface area to volume ratio.

Revision cards

Say the answer first, then flip the card to check it.

Where to go next

Solve it
Virtual Microscope
Focus on cells and tissues and measure them with a scale bar
Open the tool
Learn it
Cell Biology
The fundamental unit of life: organelles, membranes and how cells work
Start the course
Test it
GCSE Biology Higher
A new exam-style paper every day, with instant marking and a mark scheme
Start today's paper