Transcript BioGenesis Redi`s Experiment

Origin of Life
Redi’s Experiment
Challenged the idea of spontaneous generation
– (SP: belief that life came from nonliving things)
– proved that flies laid the eggs that caused other flies
SPALLANZANI’S
EXPERIMENT
hypothesized
that microorganisms
formed from other
microorganisms. (not
from SP)
boiled broth became
contaminated only
when microorganisms
from the air entered
the flask.
Pasteur’s Experiment
Placed broth in flasks w/ curved neck
T0 prevented microorganisms, from entering
Broth boiled inside remained clear for up to a
year.
When the curved necks was broken off, the broth
became contaminated w/ microorganisms
Settled the debate: spontaneous generation did
not occur
Topic: Biogenesis #1
Date: 12-7-09
1. What is spontaneous generation?
2. Who was the first to question
spontaneous generation?
3. Describe his experiment.
4. Who finally disproved spontaneous
generation?
History of Life…theory
Cells may evolve and change, but new
cells always arise from existing cells. How,
then, did the first cells originate?
scientists attempt to reconstruct the
processes that gave rise to the first cellular
life.
Earths Age:
4.6 billion years old
Was made from studying
layers of sediment in Earth’s
crust.
Radioactive dating is also
used to determine the age of
Earth
RADIOACTIVE DECAY
Can date objects
Ex. Ages of fossils and
rocks can be determined by
measuring the amount of
radioactive decay that has
occurred
1st organic compounds
Oparin:
early atmosphere consisted of:
NH3, H2; H2O, and compounds
made of hydrogen and carbon,
such as methane, CH4.
Energy from lightening caused
a rxn to form early proteins
Miller and Urey’s Apparatus
Miller and Urey’s
Tested Oparin’s
theory
Used apparatus
containing similar
chemical makeup of
the atmosphere
Added electricity
Organic compounds
formed: Nucleic
acids, ATP, amino
acids
Cell Like Structures
Under early Earth
conditions, membranebound structures have
been formed in the
laboratory
these structures may
have replicated
molecules of RNA
Believed to be the 1st
cells
First Prokaryotes
Because there was no O2, the
1st organisms were:
– Anaerobic
–Prokaryotes
–Heterotrophs
The 1st Autotrophs
Chemosynthesis:
Ex. Archaebacteria
Live in harsh conditions
Use CO2 for food
1st Eukaryotes
Through endosymbiosis (mutually
beneficial relationship) small prokaryotes fused
w/ lger prokaryotes
Believed to be the 1st organelles such as
mitochondria and chloroplasts
The “organelles” carried out aerobic respiration
and contained DNA
Topic: Biogenesis #2
1. How old is Earth believed to be?
2. Explain the difference b/w
radioactive and Carbon dating.
3. Who was the first to create organic
compounds from inorganic
compounds?
4. What is endosymbiosis?