1. History of Cell Discovery
Chapter 4

2. Microscope view of cells
Robert Hooke – first to see cells!
designed microscope that he was
able to view cork cells with (1665).
Named “Cells” because
they look like monk quarters
Cells with stone beds

3. Microscope view of cells
Anton Van Leeuwenhoek – first to see living cells.
improved design, and was
able to view red blood cells
and bacteria.
Called them "animalicules"

4. Scientists of Cell Theory
Theodore Schwann – zoologist who observed that the tissues of animals had cells (1839)

5. Scientists of Cell Theory
Mattias Schleiden – botanist who observed that the tissues of plants had cells (1845)

6. Scientists of Cell Theory
Rudolf Virchow – reported that every living thing is made up of cells, and that these cells must come from other cells.

7. Cell Theory All living things are made of one or more cells.
2. Cells are the basic unit of structure and function in organisms.
(the smallest unit that can perform life functions)
3. All cells come from pre - existing cells.

8. Terms
Cell – the smallest unit that can carry on the processes of life.
Unicellular – consists of only one cell
Multicellular – consists of more than one cell

9. Basic cell Structures Cell Membrane – outer boundary
Nucleus – control center
Cytoplasm – stuff between membrane & nucleus

10. Two Basic Cell Types Prokaryotic – lacks internal organelles.
Has a cell membrane & a cell wall
Has NO nucleus.
Means “before the nucleus”
Usually Unicellular organisms
Ex: Bacteria

11. Two Basic Cell Types Eukaryotic – contains organelles. Has a nucleus
Has a cell membrane
Usually multicellular organisms
Ex: Plants, animals, and protists

12. The First Cells & Their Environment

13. The First Cells Environment during time of first cells: No oxygen
The first cells were:
Anaerobic (Does not use oxygen)
Prokaryotic (Cells that have no nucleus)
Heterotrophic (Consumers)

14. The First Cells
The first autotrophs (make own food) used chemosynthesis (gives off CO2).
Around 3 billion years ago, photosynthetic life had began (gives off O2).
This production of oxygen was the start of aerobic organisms (use O2 to produce energy

15. Endosymbiosis
Eukaryotes evolved from a mutually beneficial relationship with prokaryotes.
Endosymbiosis – Eukaryotic cells engulf prokaryotic cells. Prokaryotic cells then performed beneficial actions inside the eukaryotes while eukaryotes provided a safe environment for the prokaryotes.

16. Spontaneous Generation
Before the 17th century, people believed that living things could come from nonliving things.
The Cell Theory has not been written.
Example: Rotting meat Maggot
Biogenesis – Living things come from other living things

17. Redi’s Experiment Control group – Uncovered jar that contained meat
Experimental group – Netting-covered jar
Allowed air to enter and prevented flies from landing on meat
Results: Maggots seen in jar without netting, but not seen in jar with netting

18. Pasteur’s Experiment
The invention of microscopes allowed people to discover microorganisms.
People believed these microorganisms developed spontaneously from the air.
Louis Pasteur created an experiment where broth from boiled meat was placed in a curve-necked flask.
Air could enter through the neck, but solid particles could not.

19. Pasteur’s Experiment: Cont’d
Results
Broth boiled inside the flask remained clear for one year.
After necks were broken off, broth became cloudy and contaminated with microorganisms after one day.
Conclusion
Microorganisms come from other microorganisms (NO SPONTANEOUS GENERATION)