Download Origins of Life PPst

Theories of the
Origin of Life
Is the veal using its meaty powers
to create maggots from itself?
Spontaneous Generation
The theory of life arising
out of nonliving matter.
Francesco Redi
Began the work to
disprove the theory of
spontaneous
generation.
Redi’s Experiment
Redi used a number of different containers.
He placed meat, fish, etc. in them.
He noticed that the containers which were closed did
not display the theory of spontaneous generation.
Only containers which were left open to the air
displayed the theory of spontaneous generation—
maggots grew out of the meat, fish, etc.
Redi’s Experiment
Louis Pasteur
Provided the final
nail on the
coffin of
the theory of
spontaneous
generation!
Pasteur’s Experiment
Pasteur decided to disprove the remaining evidence to the
theory of spontaneous generation—which dealt with the idea
that although macro-organisms, like maggots and mice, could
not be created from non-living items, mold and bacteria could.
He took some broth and heated it up in flasks which were open
to the air.
As predicted, the broth became dark in color as bacteria grew in
it.
He believed that bacteria were floating in the air, and wanted to
prove this by making it impossible for these bacteria to reach
the broth.
Pasteur’s Experiment
Therefore, he chose to use some flasks which had swan necks,
and some flasks which were open to the air.
The flasks which were open to the air became cloudy as
bacteria began to grow from the heated broth.
However, the broth which was heated in the flasks with the
swan necks remained clear!!
Instead, bacteria and dust particles accumulated in the lower
portion of the neck of the flask—proving that the bacteria came
from the air, and not from the broth.
This helped to completely disprove the theory of spontaneous
generation.
Interactive Version of the
Experiment
http://bcs.whfreeman.com/thelifewire/content/ch
p03/0303s.swf
Abiogenesis
So… the theory of spontaneous generation has been
disproved, but how did life, then, arise in our world?
The theory of abiogenesis helps to explain this. The theory of
abiogenesis refers to the origin of life—how it was created
out of nonliving matter.
Although somewhat similar to the theory of spontaneous
generation, this theory refers to how the first living
organisms were created out of “nothing!”
Abiogenesis
A = “not”
Bio = “life”
Genesis = “birth” or “creation”
Abiogenesis is the birth or creation of life from nonliving things.
In other words, the origin of life came from nonliving
items! Small molecules came together to form nucleic
acids which in turn managed to enter some sort of
circular layer of fat which could now self-replicate,
creating the first organisms!
Miller-Urey Experiment
The Miller-Urey experiment is an experiment which proved the
theory of abiogenesis.
These two researchers created an apparatus which heated up
water containing certain basic molecules such as CO, CH4, H2,
etc.
As the solution was heated, the vapor of the solution traveled
through the apparatus and was shocked with electrodes.
This shocking process was to mimic the lightning which was
believed to occur frequently in ancient earth.
Miller-Urey Experiment
As these molecules went through the system, the liquid
became darker and darker.
When Miller and Urey checked the liquid, they saw that
nucleotides had formed in the solution!!
Therefore, the conditions of ancient Earth could have,
by themselves, allowed the initial molecules to join
together to create life (GENESIS of BIO) out of nonliving
(ABIOTIC) factors.
Miller-Urey Experiment
Exit Slip
Is the theory of spontaneous generation credible?
Please provide your reasons why.
How does it differ from abiogenesis?