4. The Cell Theory Complete
The 3 Basic Components of the Cell
Theory were now complete:
1.All organisms are composed of one or
more cells.
2. The cell is the basic unit of life in all
living things.
3. All cells are produced by the division of
preexisting cells.
5. Modern Cell Theory
Modern Cell Theory contains 4 statements, in
addition to the original Cell Theory:
The cell contains hereditary information(DNA)
which is passed on from cell to cell during cell
division.
All cells are basically the same in chemical
composition and metabolic activities.
All basic chemical & physiological functions are
carried out inside the cells.(movement,
digestion,etc)
Cell activity depends on the activities of sub-
cellular structures within the cell(organelles,
nucleus, plasma membrane)
6. Cell theory facts
5 minute activity:
Use the internet to find 3 interesting or bizarre facts about
cells
PS, we already know that the human body is made up of
roughly 100 trillion cells, so find a different fact!
8. Exploring surface
area and volume
Head to the following link:
http://bit.ly/1n0AROF
Explore the relationship between surface
area and volume.
What do you notice happens to surface
area as the volume is increased?
9. Implications of Cell
Theory
The same principle applies to cells. If the volume
increases the surface area will also increase, but at
a lower rate.
What happens to the surface area/volume ratio as the
size of a cell increases?
10. The Limits of Cell Size
The cell surface (cell
membrane) is the site of particle
exchange between the inside of
the cell and the external
environment
The cell surface must allow for
sufficient movement of particles
and nutrients into the cell and
waste products out of the cell.
11. The Limits of Cell Size
Surface-area to volume ratio too small = decreased
rate of chemical exchange cell dies
Therefore…
in order to build
larger organisms,
they must be built
up from small cell
subunits.
