Introduction to Cell. Cell is the basic unit of life. Every living things are composed of cells..........................................................................................................................................................................................
1. The human body contains
about 40 trillion cells.
The human brain accounts for about
80 million cells. But, there are more
bacterial cells than human cells in the
body. Around 95% of your body
consists of bacteria, which mainly
reside on the skin and in the digestive
tract.
2. How do the following function together?
Liver, Stomach and Pancreas
A. cells
B. organ
C. tissues
D. system
21. Cells are the building blocks of living things.
Cells
A cell is the smallest independent unit of a living thing.
22. Robert Hooke was the first scientist to
discover cells.
Robert Hooke
In 1665, he used a microscope and
observed cork.
In the cork, he noticed little rooms, or
“cells,” like monks lived in.
This is how cells were named.
23. Quick Check
What are the smallest building blocks of living things called?
Who was the first scientist to discover cells?
24. Cell Theory
As scientists continued to study cells, they realized that:
All living things are made of cells.
1
A cell is the smallest unit of life.
2
Cells make more cells.
3
25. These parts are like the organs of your body:
they have a specific purpose.
Cell parts are called "organelles."
Cell Theory
Cells are made of even smaller parts.
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26. Cell Theory
There are even different types of cells.
For example, animal cells and plant cells are different from each other.
Animal Cell
Found in both cells
cell membrane
cytoplasm
nucleus
Plant Cell
cell wall
permanent
vacuole
chloroplast
Found in plant cells only