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Topic – Cells: The Building Blocks of All Organisms

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Read about cells, or click on the play button below to listen aloud.

Cells: The Building Blocks of All Organisms 

The human body is made of trillions of cells

Did you know that cells are the building blocks of all organisms on Earth? All living organisms are made up of tiny parts called cells. A cell is the smallest part of an organism, but this tiny part holds everything needed to carry out actions to keep the organism alive. Cells take in nutrients and turn them into energy. They also get rid of wastes, do work, and reproduce. Cells are vital!

Organisms made up of only one cell are unicellular. For example, an amoeba is a unicellular organism that is very tiny. It can only grow to a certain size and cannot be seen with the naked eye. Organisms made up of more than one cell are multicellular. For example, humans are multicellular and can grow to different sizes.

Cell Parts

Cells are classified into either plant or animal cells. Plant and animal cells are very similar and contain most of the same parts. All cells are filled with a jelly-like fluid called cytoplasm. This fluid contains many chemicals that help the cell stay alive. In addition, every cell has a cell membrane that keeps the cytoplasm inside. The cell membrane also keeps the parts of the cell together. Most cells have a nucleus, which is the cell’s command centre. The nucleus directs the cell’s actions and contains the DNA. DNA is the genetic material that lets cells reproduce themselves. It also lets them pass their traits on to new cells.

How Do We See Cells?

A microscope is needed to see most cells clearly. A light microscope can help you see bacteria and their structures, including the nucleus. The best microscope is the electron microscope. With it, you can see things much smaller than a cell.


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