Transcript How does life begin? - Doral Academy Preparatory

Spontaneous generation
vs. biogenesis
SPONTANEOUS GENERATION
In the early 1600’s,
some scientists believed that
life began
spontaneously!
SPONTANEOUS GENERATION
 Process by which life begins when
“magical ethers” enter non-living things to
make them alive
 Examples: mice were thought to come
from garbage piles, geese from the mud
banks of the river, maggots from meat
 In the 1600’s, scientists began
challenging this idea.
Francesco Redi
Redi’s Experiment
Set-up
3 jars with rotting
meat
1. Open top
2. Sealed with lid
3. Covered with
cloth
Observations
1. Maggots
2. No maggots
3. No maggots
Lazzaro Spallanzani
Spallanzani’s Experiment
Set-up
Nutrient broth
heated
1. Flask left open
2. Flask sealed
Observations
1. Bacteria grew
2. No bacteria
grew
Louis Pasteur
Pasteur’s Experiment
Set-up
Nutrient broth
heated
1. Flask with
curved neck
2. Flask with
straight neck
Observations
1. No dust could
reach broth, no
bacteria grew
2. Dust settled,
bacteria grew
EVIDENCE AGAINST
SPONTANEOUS
GENERATION
• The experiments of Redi,
Spallanzani, and Pasteur showed
the life does not arise spontaneously
• LIFE must come from LIFE
• These experiments supported the
theory of biogenesis
BIOGENESIS
BIO= life
GENESIS= the beginning
BIOGENESIS
Living things come from
other living things. They do
not arise spontaneously!