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Cells are the basic building blocks of all living organisms. Learn about cell structure, the similarities and differences between plant and animal cells and the different types of specialised cells.
This lesson includes:
- three videos to help you understand about cells, their structure and the different types of specialised cells
- three practise activities to help reinforce learning
All living things are made up of cells
Most cells are so small that you can only see them with a microscope
Cells have different components and each performs its own function within the cell
Specialised cells have a specific role to perform
In this film, we hear from a forensic scientist who explains the structure of an animal cell:
What’s in a cell?
Cells are the basic building blocks of all animals and plants.
Inside cells are various structures that are specialised to carry out a particular function. Both animal and plant cells have these components:
Cell membrane – this surrounds the cell and allows nutrients to enter and waste to leave it.
Nucleus – this controls what happens in the cell. It contains DNA, the genetic information that cells need to grow and reproduce.
Cytoplasm – this is a jelly-like substance in which chemical reactions happen.
Mitochondria – these are the powerhouse of the cell. They are structures where respiration takes place.
How are plant and animal cells different?
Plant cells have all the parts in the list above, plus a few extra structures:
Cell wall - this is an outer structure that surrounds the cell and gives it support.
Vacuole - this is a space within the cytoplasm of plant cells that contains sap.
Chloroplasts - these contain chlorophyll and are the site of photosynthesis.
How big are cells?
Cells can vary greatly in size. You need a microscope to see most human cells.
Red blood cells are some of the smallest cells in the human body. These have a diameter of 0.008 mm, meaning a line of 125 red blood cells is only 1 mm long.
The ovum (or egg cell) is one of the largest cells in the human body. It has a diameter of roughly 0.1 mm, so you can see them without a microscope. A line of 10 egg cells is 1 mm long.
What are specialised cells?
Most cells share features such as having a nucleus, a cell membrane, cytoplasm and mitochondria.
There are differences between cells, too. Each type of cell, has its own job to do. These cells have special features that allow them to perform their functions effectively.
Here are some examples of specialised cells:
- Red blood cells carry oxygen around the body
- Nerve cells transmit electrical signals
- Muscle cells bring parts of the body closer together
Learn about specialised cells from a sports therapist:
There are lots of fun ways to practise what you know about cells.
Drag and drop the labels to the correct part of the animal cell:
Test your knowledge of cells in this quiz:
Try making a model animal cell at home yourself:
Have a go
There's more to learn
Have a look at these other resources around the BBC and the web.