Page 71 - Science Course 1 (Book 1)

Mo3-L2a: What Make Up a Cell?

Let’s Begin Key Concept

What Make Up a Cell?
Understanding Cells How did scientist’ understanding of cell
cells develop?
English scientist Robert Hooke first identified cells
over 300 years ago while looking at cork under a
microscope he built

After Hooke’s discovery, other scientists began to use
better microscopes to identify different structures in
the cells of plants and animals.
Basic Cell Substances
The main ingredient in any cell is water.
Cell theory includes three principles.
A water molecule has two areas:
CELL THEORY •The negative (–) end can attract the positive part

All living things are made of another substance.
of one or more cells.
•The positive (+) end can attract the negative part of
another substance.

+

The cell is the smallest
unit of life. - -

Water and salt both have positive and negative parts.
All new cells come from preexisting cells.

Chloride Oxygen
Salt
(sodium chloride) Hydrogen Sodium
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