Origin of Life Power Point Presentation on Evolution

Redi used open & closed flasks which contained meat.
His hypothesis was that rotten meat does not turn into flies.
He observed these flasks to see in which one(s) maggots would develop.

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Origin of LifeOrigin of Life
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Aristotle (384 –322 BC)Aristotle (384 –322 BC)
Proposed the theory of Proposed the theory of
spontaneous generationspontaneous generation
Also called Also called abiogenesisabiogenesis
Idea that Idea that living things can living things can
arise from nonlivingarise from nonliving matter matter
Idea lasted almost Idea lasted almost 2000 years2000 years
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Spontaneous GenerationSpontaneous Generation
For centuriesFor centuries, , people basedpeople based their their
beliefsbeliefs onon their interpretations of their interpretations of
what they sawwhat they saw going on in the world going on in the world
around them without testing their around them without testing their
ideasideas
They They didn’t use the scientific didn’t use the scientific
methodmethod to arrive at answers to their to arrive at answers to their
questionsquestions
Their conclusions were based on Their conclusions were based on
untested observationsuntested observations
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Examples of Examples of
Spontaneous Spontaneous
GenerationGeneration
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Example #1Example #1
Observation:Observation: Every year in the Every year in the
spring, the spring, the Nile River floodedNile River flooded
areas of Egypt along the river, areas of Egypt along the river,
leaving behind nutrient-rich mud leaving behind nutrient-rich mud
that enabled the people to grow that enabled the people to grow
that year’s crop of food. that year’s crop of food.
However, along with the muddy However, along with the muddy
soil, soil, large numbers of frogslarge numbers of frogs
appeared that weren’t around in appeared that weren’t around in
drier timesdrier times
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Example #1Example #1
Conclusion:Conclusion: It was perfectly It was perfectly
obvious to people back then obvious to people back then
that that muddy soil gave rise to muddy soil gave rise to
the frogsthe frogs
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Example #2Example #2
Observation:Observation: In many parts of In many parts of
Europe, medieval farmers stored Europe, medieval farmers stored
grain in barnsgrain in barns with thatched with thatched
roofs (like Shakespeare’s house). roofs (like Shakespeare’s house).
As a roof aged, it was not As a roof aged, it was not
uncommon for it to start leaking. uncommon for it to start leaking.
This could lead to This could lead to spoiled or spoiled or
moldy grainmoldy grain, and of course there , and of course there
were were lots of mice aroundlots of mice around..
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Example #2Example #2
Conclusion: It was obvious to It was obvious to
them that the them that the mice came mice came
from the moldy grain.from the moldy grain.
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Example #3Example #3
Observation:Observation: In the cities In the cities
centuries ago, there were no centuries ago, there were no
sewers, no garbage trucks, no sewers, no garbage trucks, no
electricity, and no refrigeration. electricity, and no refrigeration.
Sewage flowed down the streets, Sewage flowed down the streets,
and chamber pots and left over and chamber pots and left over
foodfood were thrown out into the were thrown out into the
streets each morning. Many cities streets each morning. Many cities
also had major also had major rat problemsrat problems and a and a
disease called disease called Bubonic plagueBubonic plague..
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Example #3Example #3
Conclusion:Conclusion: Obviously, all Obviously, all
the the sewage and garbage sewage and garbage
turned into the ratsturned into the rats.
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Example #4Example #4
Observation:Observation: Since there were no Since there were no
refrigerators, the mandatory, refrigerators, the mandatory,
daily trip to the butcher shop, daily trip to the butcher shop,
especially in summer, especially in summer, meant meant
battling the flies around the battling the flies around the
carcassescarcasses. Typically, carcasses . Typically, carcasses
were “hung by their heels,” and were “hung by their heels,” and
customers selected which chunk customers selected which chunk
the butcher would carve off for the butcher would carve off for
them. them.
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Example #4Example #4
Conclusion: Obviously, the Obviously, the rotting rotting
meatmeat that had been hanging in the that had been hanging in the
sun all day was the sun all day was the source of the source of the
fliesflies. .
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Abiogenesis RecipesAbiogenesis Recipes
Recipe for bees:Recipe for bees:
Kill a young bullKill a young bull, and , and bury itbury it
in an upright position so in an upright position so
that its that its horns protrude from horns protrude from
the groundthe ground. After a month, . After a month,
a swarm of bees will fly out a swarm of bees will fly out
of the corpse. of the corpse.
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Abiogenesis RecipesAbiogenesis Recipes
Recipe for mice:Recipe for mice:
Place a Place a dirty shirtdirty shirt or some rags in or some rags in
an an open pot or barrelopen pot or barrel containing a containing a
few grains of wheatfew grains of wheat or some wheat or some wheat
bran, and in bran, and in 21 days21 days, mice will , mice will
appear. There will be adult males appear. There will be adult males
and females present, and they will and females present, and they will
be capable of mating and be capable of mating and
reproducing more mice.reproducing more mice.
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Disproving Disproving
Spontaneous Spontaneous
GenerationGeneration
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Francesco Redi (1668)Francesco Redi (1668)
In 1668, Francesco In 1668, Francesco RediRedi, an , an
Italian physician, did an Italian physician, did an
experiment with experiment with fliesflies and and wide-wide-
mouth jars containing meatmouth jars containing meat
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Redi’s ExperimentRedi’s Experiment
Redi used Redi used open & closed open & closed
flasksflasks which which contained meatcontained meat..
His His hypothesishypothesis was that was that
rotten meat does not turn rotten meat does not turn
into flies.into flies.
He He observedobserved these flasksthese flasks to to
see in which one(s) maggots see in which one(s) maggots
would develop.would develop.
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Redi’s FindingsRedi’s Findings
He found that if a flask was He found that if a flask was
closedclosed with a lid so with a lid so adult flies adult flies
could not get in, no maggotscould not get in, no maggots
developed on the rotting meat developed on the rotting meat
within.within.
In a flask In a flask without a lidwithout a lid, , maggots maggots
soon were seensoon were seen in the meat in the meat
because adult flies had laid eggs because adult flies had laid eggs
and more and more adult flies soon adult flies soon
appeared.appeared.
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Redi’s (1626-1697) Experiments

Evidence against spontaneous generation:Evidence against spontaneous generation:
1. 1. Unsealed Unsealed – maggots on meat– maggots on meat
2. 2. SealedSealed – no maggots on meat – no maggots on meat
3. 3. GauzeGauze – few maggots on gauze, none on meat – few maggots on gauze, none on meat
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Results of Redi’s ExperimentsResults of Redi’s Experiments
The results of this The results of this
experiment experiment disproved the idea disproved the idea
of spontaneous generation for of spontaneous generation for
larger organisms,larger organisms, but people but people
still thought microscopic still thought microscopic
organisms like algae or organisms like algae or
bacteria could arise that way.bacteria could arise that way.
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Francesco RediFrancesco Redi
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Did Redi Use the Did Redi Use the
Scientific Method?Scientific Method?
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The Scientific MethodThe Scientific Method
ObservationObservation
HypothesisHypothesis
ExperimentExperiment
Accept, Reject, or Modify hypothesisAccept, Reject, or Modify hypothesis
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Step 1 - ObservationStep 1 - Observation
There were flies around meat There were flies around meat
carcasses at the Butcher carcasses at the Butcher
shop.shop.
Where do the flies come Where do the flies come
from?from?
Does rotting meat turn into Does rotting meat turn into
or produce rotting flies?or produce rotting flies?
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Step 2 - HypothesisStep 2 - Hypothesis
Rotten meat does not turn Rotten meat does not turn
into flies. into flies. Only flies can Only flies can
make more flies.make more flies.
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Step 3 - TestingStep 3 - Testing
Wide-mouth jarsWide-mouth jars each containing a piece of each containing a piece of
meat were subjected to several variations of meat were subjected to several variations of
“openness”“openness” while all while all other variables were other variables were
kept the same.kept the same.
Control groupControl group — These jars of meat were — These jars of meat were
set out set out without lidswithout lids so the meat would be so the meat would be
exposed to whatever it might be in the exposed to whatever it might be in the
butcher shop.butcher shop.
Experimental group(s)Experimental group(s) — One group of jars — One group of jars
were were sealedsealed with lids, and another group of with lids, and another group of
jars had gauze placed over them.jars had gauze placed over them.
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Step 4 - DataStep 4 - Data
Presence or absence of fliesPresence or absence of flies
and maggots observed in each and maggots observed in each
jar was jar was recordedrecorded..
Control groupControl group – flies entered, – flies entered,
laid eggs, & maggots emergedlaid eggs, & maggots emerged
Gauze coveredGauze covered – flies on gauze, – flies on gauze,
but not in jarbut not in jar
Sealed jarsSealed jars – No maggots or – No maggots or
flies on the meatflies on the meat
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Step 5 - ConclusionStep 5 - Conclusion
Only flies can make more fliesOnly flies can make more flies . In the . In the
uncovered jarsuncovered jars, flies entered and laid eggs , flies entered and laid eggs
on the meat. Maggots hatched from these on the meat. Maggots hatched from these
eggs and grew into more adult flies. Adult eggs and grew into more adult flies. Adult
flies laid eggs on the gauze on the gauze-flies laid eggs on the gauze on the gauze-
covered jars. These eggs or the maggots covered jars. These eggs or the maggots
from them dropped through the gauze onto from them dropped through the gauze onto
the meat. In the the meat. In the sealed jarssealed jars, no flies, , no flies,
maggots, nor eggs could enter, thus none maggots, nor eggs could enter, thus none
were seen in those jars. Maggots arose only were seen in those jars. Maggots arose only
where flies were able to lay eggs. where flies were able to lay eggs. This This
experiment disproved the idea of experiment disproved the idea of
spontaneous generation for larger organisms.spontaneous generation for larger organisms.
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Disproving Disproving
Spontaneous Spontaneous
Generation of Generation of
MicrobesMicrobes
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Anton van Leeuwenhoek (1674)Anton van Leeuwenhoek (1674)
Leeuwenhoek began Leeuwenhoek began makingmaking and looking and looking
through through simple microscopessimple microscopes
He often made a new microscope for each He often made a new microscope for each
specimenspecimen
He He examined waterexamined water and visualized tiny and visualized tiny
animals, fungi, algae, and single celled animals, fungi, algae, and single celled
protozoa; protozoa; “animalcules”“animalcules”
By end of 19By end of 19
thth
century, these organisms century, these organisms
were called were called microbesmicrobes
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Anton van Leeuwenhoek 1632-1723Anton van Leeuwenhoek 1632-1723
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Leeuwenhoek’s MicroscopeLeeuwenhoek’s Microscope
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John Needham (1745)John Needham (1745)
Showed that microorganisms Showed that microorganisms
flourished in various soups that flourished in various soups that
had been exposed to the airhad been exposed to the air
Claimed that there was a Claimed that there was a “life “life
force” present in the molecules force” present in the molecules
of all inorganic matterof all inorganic matter, including , including
air and the oxygen in it, that air and the oxygen in it, that
could cause spontaneous could cause spontaneous
generation to occurgeneration to occur
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Needham’s ResultsNeedham’s Results
Needham’s experiments Needham’s experiments
seemed to supportseemed to support the idea the idea
of of spontaneous generationspontaneous generation
People People didn’t realizedidn’t realize bacteria bacteria
were already present in were already present in
Needham’s soupsNeedham’s soups
Needham Needham didn’t boil long didn’t boil long
enoughenough to kill the microbes to kill the microbes
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Needham’s ExperimentNeedham’s Experiment
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Lazzaro Spallanzani’s (1765)Lazzaro Spallanzani’s (1765)
Boiled soups for almost an hourBoiled soups for almost an hour
and sealed containers by and sealed containers by melting melting
the slender necks closedthe slender necks closed.
The The soups remained clearsoups remained clear..
Later, he Later, he broke the sealsbroke the seals & the & the
soups became cloudysoups became cloudy with with
microbes. microbes.
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Spallanzani’s ResultsSpallanzani’s Results
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ConclusionConclusion
CriticsCritics said sealed vials did said sealed vials did
not allow enough air for not allow enough air for
organisms to survive and that organisms to survive and that
prolonged heating destroyed prolonged heating destroyed
“life force”“life force”
Therefore, Therefore, spontaneous spontaneous
generation remainedgeneration remained the the
theory of the timetheory of the time
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The Theory The Theory
Finally ChangesFinally Changes
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How Do Microbes Arise?How Do Microbes Arise?
By By 18601860, the debate had become so , the debate had become so
heated that the heated that the Paris Academy of Paris Academy of
SciencesSciences offered a prizeoffered a prize for any for any
experiments that would help resolve experiments that would help resolve
this conflictthis conflict
The The prize was claimed in 1864 by prize was claimed in 1864 by
Louis PasteurLouis Pasteur, as he published the , as he published the
results of an experiment he did to results of an experiment he did to
disproved spontaneous generation in disproved spontaneous generation in
microscopic organismsmicroscopic organisms
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Louis Pasteur (1822-1895)Louis Pasteur (1822-1895)
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Pasteur's ProblemPasteur's Problem
Hypothesis:Hypothesis: Microbes come Microbes come
from cells of organisms on dust from cells of organisms on dust
particles in the air; not the air particles in the air; not the air
itself.itself.
Pasteur put broth into several Pasteur put broth into several
special special S-shaped flasksS-shaped flasks
Each flask was Each flask was boiled and placed boiled and placed
at various locationsat various locations
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Pasteur's Experiment - Pasteur's Experiment - Step 1Step 1
S-shaped FlaskS-shaped Flask
Filled withFilled with broth broth
The special shaped was The special shaped was
intended to intended to trap any trap any
dust particles dust particles
containing bacteriacontaining bacteria
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Pasteur's Experiment - Pasteur's Experiment - Step 2Step 2
FlasksFlasks boiledboiled
Microbes KilledMicrobes Killed
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Pasteur's Experiment - Pasteur's Experiment - Step 3Step 3
Flask left at various Flask left at various
locationslocations
Did Did not turn cloudynot turn cloudy
Microbes not foundMicrobes not found
Notice the Notice the dustdust that that
collected in the neckcollected in the neck of of
the flask the flask
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Pasteur's Experimental ResultsPasteur's Experimental Results
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Pasteur’s Pasteur’s S-shaped flask kept microbes S-shaped flask kept microbes
out but let air inout but let air in..
Proved microbes only come from other Proved microbes only come from other
microbes (life from life) - microbes (life from life) - biogenesisbiogenesis
The Theory of BiogenesisThe Theory of Biogenesis
Figure 1.3
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ReviewReview
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1668: 1668: Francisco RediFrancisco Redi filled six filled six
jars with decaying meat.jars with decaying meat.
Evidence Pro and ConEvidence Pro and Con
Conditions:Conditions: Results:Results:
3 jars covered with fine 3 jars covered with fine
netnet
No maggotsNo maggots
3 open jars3 open jars Maggots appearedMaggots appeared
From where did the maggots come?From where did the maggots come?
What was the purpose of the sealed jars?What was the purpose of the sealed jars?
SSpontaneous generation or biogenesis?pontaneous generation or biogenesis?
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1745: 1745: John NeedhamJohn Needham put boiled put boiled
nutrient broth into covered flasks.nutrient broth into covered flasks.
Evidence Pro and ConEvidence Pro and Con
Conditions:Conditions: Results:Results:
Nutrient broth Nutrient broth
heated, then placed heated, then placed
in sealed flaskin sealed flask
Microbial growthMicrobial growth
From where did the microbes come?From where did the microbes come?
SSpontaneous generation or biogenesis?pontaneous generation or biogenesis?
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1765: 1765: Lazzaro SpallanzaniLazzaro Spallanzani boiled boiled
nutrient solutions in flasks.nutrient solutions in flasks.
Evidence Pro and Con
Conditions:Conditions: Results:Results:
Nutrient broth Nutrient broth
placed in flask, placed in flask,
heated, then heated, then
sealedsealed
No microbial No microbial
growthgrowth
SSpontaneous generation or pontaneous generation or
biogenesis?biogenesis?
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1861: 1861: Louis PasteurLouis Pasteur demonstrated demonstrated
that microorganisms are present in that microorganisms are present in
the air.the air.
Evidence Pro and ConEvidence Pro and Con
Conditions:Conditions: Results:Results:
Nutrient broth placed in Nutrient broth placed in
flask, heated, not flask, heated, not
sealedsealed
Microbial growthMicrobial growth
Nutrient broth placed in Nutrient broth placed in
flask, heated, then flask, heated, then
sealedsealed
No microbial growthNo microbial growth
SSpontaneous generation or biogenesis?pontaneous generation or biogenesis?
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54. 54copyright cmassengale