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The first big idea: The cell

Cells are the basic building blocks of life. It is hard for us now to imagine scientists not knowing about cells, but until microscopes were developed, they couldn’t be seen, let alone described or observed.

Technology and science discovery

The invention of the microscope in the early 17th century was key to the discovery of cells and to distinguishing different types of cells.

Organisms and cells

As people began to see cells in every living thing they observed, they started to think that all living things were made of these amazing functional units, called cells. Cell theory was formed.

In fact, all life forms are built from cells. Bacteria consist of just a single cell, whereas our bodies are made up of approximately 75 trillion cells, divided into more than 200 different cell types.

Cell structure

Cells are complex and contain specialised structures to permit them to carry out a wide variety of functions.

Basic cells have an outer surface or plasma membrane, are filled with a substance called cytoplasm and contain organelles (“little organs”) that carry out specific functions depending on the cell type.

Bacteria cells are called prokaryotic, and their DNA is just floating around inside them. Plant and animal cells are called eukaryotic, and their DNA is contained within a specialised structure known as the nucleus.

Cell reproduction

Cells are able to create copies of themselves by a process called mitosis. The division of a cell from one, to two, to four forms the basis of growth and development of all living things.

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