1. And Where Did It Come From ?
What Is Life ?
And Where Did It Come From ?

2. Regardless of the Kingdom of Life We Study This Year, All Life Forms Share a Set of Common Characteristics.

3. R. H. Cager, a fictitious biologist best summed up the key characteristics of life:
R. = All organisms must be able to Reproduce either sexually or asexually.
H. = Homeostasis, all organisms have the ability to maintain a constant balance of internal conditions. Ex, Sweating to cool the body down.
C. = Cells. All organisms consist of at least one or more cells.
A. = Adaptable. All life forms have the design making them capable of becoming better suited to their environment.
G. = Growth. All organisms grow and develop (change) during their life cycle. The growth occurs through cell division.
E. = Energy Transformations. All life forms have the ability to run energy transformations to release or store energy for their cellular metabolism.
R. = Respond. All organisms have the ability to detect changes in the environment and respond rapidly or slowly.

4. Long Before Scientists had come to a decent understanding of what the key characteristics of life were, people (including scientists) had asked the question “Where Does Life Come From?”
Most scientists agreed that non-living things could be transformed into living things

5. “To create or produce without life !”
This Theory That Living could arise from non-living was known as……… “SPONTANEOUS GENERATION”
Another name for this theory was “ABIOGENESIS”
“A” prefix means without
“BIO” root word means life
“GENESIS” root word means to create or produce
“To create or produce without life !”
How was this theory laid to rest?
VERY SLOWLY !

6. Anton van Leeuwenhoek (1660s)
Developed first simple microscopes to allow scientist to start viewing life on a cellular level

7. ROBERT HOOKE
In 1665 Hooke published Micrographia. When viewing Cork under the microscope he noticed that it had the appearance of small microscopic chambers clustered together. much like prison “CELLS”

8. Francesco Redi (1668)
Hypothesized that maggots came from flies and only from flies

9. New Support For Spontaneous Generation: John Needham (mid 1700s)
Needham’s experiments involved boiling beef broth in loosely sealed flasks for a few minutes; after a few days the broth became cloudy, when observed under a scope it was teeming with microbes, which apparently were spontaneously created.

10. Spontaneous Generation: John Needham (1700s)
Needham’s Experiment
Mutton Gravy

11. Lazzaro Spallanzani (1776)
Spallanzani boiled broth longer and sealed containers tighter, and no spontaneous generation occurred.

12. Critics argued that circulating air is required for spontaneous generation
Louis Pasteur put the final nails in the “Abiogenesis Theory” coffin

13. Louis Pasteur (1861)

14. Within the next 100 years a new theory was born:
-This Theory gave us a better understanding of life, but it really didn’t help identify the origin of life. In fact it contradicts some of the main concepts involved in explaining how life originated.

15. 1. Did Life originate by accident?
2. Did Life originate by design?
3.Did Life originate by extra-terrestrial introduction? - If so refer back to #1 and #2

16. Whether by design or by accident, scientist have experimented to see if life could be generated from non-living things.
Methane, Ammonia, Hydrogen and water
Miller - Urey Experiment

17. This experiment was conducted under various conditions and many different organic chemicals (like amino acids, ATP, DNA bases and urea) were generated, but these organic molecules did not assemble to form cells
- In the absence of oxygen, many of the molecules in this organic soup tend to link together to form larger macromolecules, and the majority of a living cell is composed of these macromolecules

18. The fossil record does indicate to us that the first life forms were unicellular and used the smaller more simple inefficient cell design known as a “PROKARYOTIC” cell
Whether using a small cell or a more advanced more complex “EUKARYOTIC” cell. The processes that take place inside these cells are complex and must be precise.

19. - The real challenge is trying to explain how samples of large organic molecules know how to follow complex processes that must be precisely followed to create and sustain life. Many of these molecules need other key organic molecules to be present to be created in the first place, but those molecules require the other molecule to be present first ! ! ! !

20. This conundrum (puzzle) is one that many scientist have tried to answer. Despite trying to sound like we know all the answers, we just aren’t 100% sure. Our knowledge is of science is constantly changing.
In Fact, to really illustrate our lack of understanding for the amazing world we live in we need not look very far. The last time I checked, the highest Union of Astronomers from around the world was having a bit of trouble figuring out what a “PLANET” is !!!! Sorry PLUTO you are out.