1. Biology
The Study of Life

2. Brainstorm: What makes something living
Brainstorm: What makes something living? What are the characteristics of living things?

3. Class Brainstorm
Block 3
Block 2

4. Characteristics of Living Things
Composed of Cells
Complex Organization
Use Energy
Grow/Develop
Reproduce
Homeostasis
How do we know?
complex organization: (cell parts, groups of cells, specific functions, size, lifespan)

5. The Microscope iphone of the 1600s
allowed scientists to observe living tissues in detail
many scientists built their own

6. Robert Hooke English Scientist
Drew detailed sketches of his observations
Compiled in Micrographia (1665)
Observed thin slices of cork from cork oak trees
named the structures cells!

7. Antonie van Leeuwenhoek
Dutch scientist, lensmaker
looked at pond scum, blood from different organisms, etc
first to describe microorganisms 1674
called them animalcules!
cells present in animals too!

8. And then… Hooke(1665) and Leeuwenhoek(1674)
What were scientists doing for 200 years?
1830s Cell Theory was finally was proposed!

9. Spontaneous Generation
Widely accepted belief: living things could come from non-living things
Observations:
rotting meat - maggots
corn husks/dirty rags - mice
muddy riverbank - frogs
Conclusion:
Living things could come from non-living things! (Spontaneous Generation)

10. Van Helmont
Flemish chemist, psychologist, physician

11. Francesco Redi Italian physician, biologist, poet
Challenged spontaneous generation (rotting meat - maggots) with controlled experiment (1668)

12. John Needham English biologist, botanist, Roman Catholic Priest
Boiled meat infusions
Looked at microorganisms
Grew in both flasks, including sealed one
Spontaneous generation of microorganisms?
What was wrong with his experiment?

13. Lazzaro Spallanzani Italian biologist, physiologist, Catholic priest
Experiment to disprove spontaneous generation of microorganisms
Critics: But you cut off the oxygen!

14. FINALLY: Louis Pasteur 1864
Used ``swan-necked`` flask
Confirmed that new bacteria come only from existing bacteria!

15. Development of Cell Theory
1824 – Henri Dutrochet
plants grow by increasing number of cells
Robert Brown
described cell nucleus
Matthias Schleiden
all plant parts are made of cells
Theodor Schwann
all animal tissues are composed of cells
1858- Rudolf Virchow
cells must arise from preexisting cells

16. Cell Theory All organisms are composed of one or more cells.
The cell is the basic unit of life in all living things.
All cells are produced by the division of preexisting cells.

17. Cells Video

18. Exit Slip
Make a table to sort the following into living (biotic) and non-living (abiotic):
Toenail Sun Hair
Nerve Cell Leaf
Fire Tree bark Water
Algae Bacteria
2) How did the microscope contribute to the development of cell theory?
3) How did the swan-necked flask contribute to the development of cell theory?
Biotic (living)
Abiotic (non-living)