1. Microscopes Provide the Windows to the World of the Cell
The Cell Theory
Microscopes Provide the Windows to the World of the Cell

2. The Men Anton Van Leeuwenhoek (1600’s) Credit for the first microscope
Looked at pond water and saw “wee beasties”

4. Robert Hooke Observed plant stems, wood, and cork (1600’s)
Saw all the tiny chambers and called them CELLS
What cell part did Hooke observe?
Cell Wall

6. Robert Brown (1833)
Observed that cells had a dark structure within plant cells
Brown observed the nucleus

7. Matthias Schleiden (1838) Stated that all plants are made of Cells
Made many observations of plants around the area

8. Theodor Schwann (1839) Stated that all animals are made of Cells
Observed many animal tissues

9. Rudolf Virchow (1855)
Stated that all cells come from pre-existing cells
Cells arise from the division of pre-existing cells

10. The Cell Theory All living things are composed of cells
Cells are the basic unit of structure and function in living things
All cells come from pre-existing cells

11. Exceptions to the Cell Theory
Viruses – are not cellular
Mitochondria and chloroplast – each contain genetic material and can reproduce

12. Endosymbiotic Theory What is this?
Concerns the origins of mitochondria and plastids (chloroplasts) from prokaryotic cells
Endosymbiont
Cell that lives within another cell

13. Endosymbiotic Theory
Endosymbionts gained entry to cell as undigested prey items or parasites and began a mutually beneficial relationship
Occurred by endocytosis (cell parts are engulfed)
Over time this would turn into a single organism whose parts are inseparable

14. Endosymbiotic Theory Evidence
Mitochondria & Plastids
Have enzymes and transport systems that are the same as in plasma membrane of prokaryotes
Also replicate by same process as certain prokaryotes

15. Endosymbiotic Theory Evidence Cont’d
Both organelles have DNA, have mechanisms to transcribe /translate proteins
Size, Nucleotide Sequence, & Sensitivity to antibiotics are similar to prokaryotes