Introduction to Cell Theory

1
Introduction to Cell Theory
History of Scientists
1655
Robert Hooke coins the term "cell" to describe
chambers in cork
Anton Von Leeuwenhoek perfects techniques for
grinding microscope lens to make the first
microscope
1674
Mathais Schleiden concluded that plants are
composed of cells
1838
Theodore Schwann concluded that animals are
composed of cells
1839
2
Cell Theory
Those early scientists did experiments on living
things and developed CELL THEORY
Main Ideas of Cell Theory
3
What are cells made of?
Cells are mostly water. The rest of the present
molecules are

• protein

• nucleic acid

• carbohydrate

• lipid

• other

4
What are cells made of?

• By elements, a cell is composed of
• 60 hydrogen
• 25 oxygen
• 10 carbon
• 5 nitrogen

5
Special Cell Process

• There are approx. 100 trillion cells in the human
  body
• 100,000,000,000,000
• Cells need certain substances to stay alive

• ANSWER
• Osmosis
• Diffusion

QUESTION How do they get these substances?
6
Rules of Diffusion Osmosis

• All substances that enter or leave a cell must
  cross its surface
• Small cells function better than large cells
• WHY? because substances do not have to travel
  as far to reach the center of small cells
• So, the larger the cellthe longer it takes to
  cross it

7
Osmosis-
the movement of water across the cell membrane

• important because cells are surrounded by water
  molecules

• the number of H2O molecules inside and outside
  the cell must be almost equal.

when the molecules are even throughout a space
Equilibrium-

• the process of osmosis allows this balance to
  happen

8
Diffusion
Diffusion the movement of particles from an
area of high concentration to an area of low
concentration.
9
Diffusion Animation