1. Biogenesis The First Cells Cell Theory Cells and Technology
Life From Life
Biogenesis
The First Cells
Cell Theory
Cells and Technology

2. What is Life?
There are 5 main characteristics that scientists have decided are present in living things
They are…

3. 1. Living things need energy

4. 2. Living things produce wastes

5. 3. Living things respond and adapt to their environment

6. 4. Living things reproduce

7. 5. Living things grow

8. Abiogenesis or Biogenesis? pg. 258 - 259
Abiogenesis – believed for 2000 years – living things can appear from non-living things
Controlled experiments disproved abiogenesis and led to new theory – BIOGENESIS

9. Francesco Redi (1668) Placed meat in an uncovered jars
Placed meat in jars covered with cheesecloth (air but not flies could pass through)
A few days later…….

10. Maggots were found in uncovered jars only!
Redi was convinced that maggots are not reproduced by abiogenesis.

11. Although Abiogenesis was disproved, scientists still did not know how new forms of life appeared.

12. LOUIS PASTEUR
Investigated FERMENTATION, a process that converts grape juice to wine, barley to beer, sours milk.
He hypothesized that the “active principle” in the air that caused this convention was an organism.

13. Pasteur’s Experiment
• HYPOTHESIS: air itself is the “active principle” because it contains microbes.
TEST: exclude air from nutrient broth and it will not teem with life.

15. Redi and Pasteur attempt to disprove abiogenesis

16. Rudolf Virchow
German physicist suggested the theory of BIOGENESIS in 1858
BIOGENESIS = LIVING ORGANISMS CAN ONLY ARISE FROM OTHER LIVING ORGANISMS

17. Robert Hooke, Microscopes and the Cell Theory

18. Microscopes and the Cell Theory pg. 261 - 265
Robert Hooke 1665 – saw cork “boxes” which reminded him of monk cells so he called them “cells”
However, it was decades before
scientists realized that cells were
an amazing discovery and were
common to all living things!

19. More Discoveries Anthony van Leeuwenhoek
builds a microscope that could magnify up to 500X and becomes the first person to describe single-celled microorganisms.

20. More Discoveries
Schleiden and Schwann determine that plants and animals were composed of cells
but they still believed in abiogenesis.

21. More Discoveries
Virchow concludes that cells can only arise from other cells and the cell theory is born. Virchow concludes that cells can only arise from other cells.

22. Current Cell Theory All organisms are composed of one or more cells
The cell is the smallest functional unit of life
All cells are produced from other cells

23. Microscopes pg
Complete your notes using your textbook