1. EQ: How are a cells organelles like the infrastructure of a city?
What are cells?
EQ: How are a cells organelles like the infrastructure of a city?

2. What are cells?
Cells are the smallest unit that is capable of carrying on life functions
Most cells are so small they cannot be seen by the naked eye

3. Cell Discovery
Because of their size, cells were not discovered until the mid-1600’s by Robert Hooke
He looked at a thin slice of cork and noted that the cork looked like it was made of little boxes.
Robert Hooke called these little boxes “cells” because they resemble tiny rooms

4. Little boxes or “cells”

5. Hooke also looked at… Plants Feathers Fish scales
And the eyes of houseflies!
But he spent most of his time looking at plants and fungi.
They were easier to see because plant cells have cell walls, and animal cells do not.
Since he couldn’t see the animal cells due to the absence of cell walls, he thought only plants were made of cells!

6. Cell Discovery
In 1673, a Dutch merchant named Anton Van Leeuwenhoek, used a microscope he built himself to look at pond scum

7. He saw small organisms in the water
He named these organisms “animalcules” which means “little animals”.
We call these single-celled animals protists
Leeuwenhoek also looked at…
Animal blood
Yeasts
And was the first person to see bacteria!

8. Cell Theory
Different scientists studied both plants and animal cells during this time, but in 1839, Theodor Schwann wrote the first two parts of what is now known as cell theory:
All organisms are made of one or more cells
The cell is the basic unit of all living things
Later, another scientist added the third part of cell theory:
All cells come from existing cells

9. Types of Cells Prokaryotic An organism that is made of a single cell
No nucleus
Have a tail called flagellum
They have a cell wall
Bacteria, Archea

10. Types of Cells Eukaryotic
Have a nucleus, and other membrane-bound organelles.
Anything not considered bacteria or archea are eukaryotic
Plants, Animals, Fungi, Protists

11. Cell Size Most cells are too small to be seen without a microscope.
There is a reason why most cells are so small….
Cells take in food and get rid of wastes through their outer surface.
As a cell gets larger, it needs more food and produces more waste.
Therefore, more materials pass through its outer surface.
As the cell’s volume increases, its surface area grows as well.
But the cell’s volume grows faster than its surface area.
If a cell gets too large, the cell’s surface area will not be large enough to take in enough nutrients or get rid of its wastes

12. Cell Size
There are some exceptions…..
Egg yolk --- one BIG CELL

13. Cell Composition
Cells are 90% water

14. What makes up the other 10%?
Of that remaining 10%.....
50% is proteins (5% of total cell make up )
DNA
15% carbohydrate (1.5% of total cell make up)
sugars
15% nucleic acid (1.5% of total cell make up)
10% lipid (1% of total cell make up)
Fats
10% others (1% of total cell make up)

15. Cell Composition