Origin of Life
Objective 3.05
Biogenesis vs. Abiogenesis
Earth’s early atmosphere & life
Biogenesis vs. Abiogenesis
• Biogenesis: Theory that all living things come
from other living things.
• Abiogenesis: Theory that living things can
come from nonliving things.
– Scientists have done several experiments to
disprove this theory
Louis Pasteur
• Experiment: Where do microbes come from?
– Used S-shaped flask
– Heated broth and nothing grew for 1 year (dust got
trapped in the curve)
– Removed S-shaped neck and broth got cloudy in 1
day (growth)
– Concluded that the microbes came from the air, NOT
from the broth.
• Result: Disproved Abiogenesis
Francesco Redi
• Experiment: Do flies come from rotten meat?
– Put meat in jars. One jar had a net covering, the other
jar was open.
– The open jars had maggots on the meat
– The closed jars had no maggots.
– Concluded that adult flies were able to lay their eggs on
the meat in an open jar and could not get to the meat in
the netted jar.
• Result: Disproved abiogenesis.
So…
• Abiogenesis was disproven.. Life must come
from other life..
• But where did living things come from??
Earth 4.6 Billion Years Ago
• Atmosphere was very different than today.
– No oxygen
– Thick, gassy atmosphere and hotter temperatures
– Too hot for liquid water
– Volcanoes
About 3.8 Billion Years Ago…
• The Earth began to cool
• Thunderstorms drenched the Earth
• Oceans formed!
Alexander Oparin’s Hypothesis
• Thought
Heat + Gases in air = Organic Compounds
(Sun)
(Methane)
(Amino Acids)
(Lightning) (Ammonia)
(Hydrogen)
NO
Necessary for
OXYGEN
life to evolve!!
Miller & Urey Tested Oparin’s
Hypothesis
• Discovered he was right!
Origin of Cells
1st: Anerobic Prokaryotic Cells
2nd: Photosynthetic Prokaryotic Cells
3rd: Aerobic Prokaryotic Cells
4th: Aerobic Eukaryotic Cells
Origin of Eukaryotic Cells
• Endosymbiont Theory: theory that larger
prokaryotes took in smaller prokaryotes and
worked together to form a more complex cell
(Eukaryotic Cell!)
• Mitochondria and chloroplasts have their own
DNA, so that strengthens the argument that
they were, at one time, prokaryotes
themselves.
-Also, DNA is
circular like in
bacteria
- And,
mitochondria and
chloroplasts
actually have
ribosomes in them!
Darwin & Evolution
Objective 3.05
Historical development of the theory
of evolution by natural selection
Shared anatomical structures
Charles Darwin
• He was a naturalist on a ship named the HMS
Beagle.
• He wrote a book called On the Origin of Species.
(1859)
• Sailed to the Galapagos Islands
3 Important Observations
1. Turtles: Different island, different habitat,
different shell shape,
and neck length
2. Marine Iguanas: Adapted to go under water and
eat algae off of rocks.
3. Birds: Different island, different habitat, different
beak shape.
Darwin’s Conclusion:
Natural Selection
• “Survival of the Fittest”
• Causes a change in a population.
• Population
– Same species
– Same area
– Can interbreed
How it works…
• The organism best suited for the
environment
–More likely to survive
–Will more than likely reproduce
–More of that trait is seen in future
generations of population.
• Natural Selection can’t be seen
immediately and can take several
generations.
Adaptations
• An inherited trait that increases the
chances of survival.
• Can be:
–Anatomical
• Porcupine quills
• Bird’s hollow bones
Adaptations, Continued
– Physiological
• Different ways plants carry out photosynthesis
– Behavior
• Animals hunting in groups.
Causes of Evolution
• EVOLUTION:
– A gradual change in a
population over time
•
•
•
•
Natural Selection
Mutations
Competition
Geographic Isolation
Example of Geographic Isolation
• Beetle population divided by a
river.
• Both groups of beetles become
different because they adapt to
their new (different)
environments.
• Even if reunited, they would not
mate with each other again
because they have evolved
genetically and behaviorally into
two different species
(speciation)!
5 Pieces of Evidence
1. Anatomy
2. Embryo Comparison
3. Biochemical (DNA)
4. Adaptations
5. Fossils
Anatomy
• Homologous Structure: Similar structure,
different function
• Analogous Structure: Different structure,
similar function
• Vestigial Structure: Structure that has no use,
but suggests that at one time it did (ex: appendix).
Embryo Comparison
• Look how similar these embryos look!
DNA Comparison
• The more DNA the organisms have in
common, the more similar they are
• Ex: The hippopotamus shares more DNA with
whales and dolphins than other hoofed
animals
Adaptations
• Inherited traits that aid in survival
– Mimicry: Acts like another organism or pretends to
be a harmful predator.
– Camouflage: Blends in for better survival
– Antibiotic/Pesticide Resistance: Some bacteria do
not respond to drugs which means they are able to
survive and multiply!
Antibiotic Resistance
• Normal H. pylori
bacteria produces
an enzyme that
activates an
antibiotic.
• That mixture
creates a “poison”
to the bacteria and
kills it.
• The bacteria
mutates to not
produce the
enzyme.
Fossils
• Evidence of once living organisms.
– Can be:
1. Bones
2. Footprints
3. Imprints
• Fossil Record: The history of life on Earth as
shown by fossils preserved in rocks.
– Shows:
1. How species changed over time
2. If any species go extinct
• The Geologic Time Scale is based on the Fossil
Record.
Fossils of the Geologic Time Scale
Age of Fossils
• Relative Age: One
fossil is older/younger
than another based on
rock layers.
– Does not tell exact age.
Age of Fossils
• Absolute Age: The more
exact age of a fossil.
– Based on decay of organisms
(Carbon Dating)
– Use half life to determine age
– Half Life: Time it takes for
half the atoms to decay.
Taxonomy
Objective 4.01:
Analyze the classification of
organisms according to their
evolutionary relationships
Classification
• Classification: to organize
things into groups that
have meaning.
• Taxonomy: a scientific
classification system used
to assign each organism
universally.
– Latin is the universal
language of scientists.
Aristotle
• 1st classification system
• Divided into 2 groups: Blood or Bloodless,
which was basically Animals & Plants.
Linnaeus
• Developed the current classification system.
• Binomial Nomenclature: two-word naming
system for each species.
The Seven Taxa
• Taxon: A group or level of organization.
• Linnaeus’s system uses 7 taxa arranged in order from
largest to smallest.
• He classified organisms into two kingdoms, Anamalia or
Plantae
1. Kingdom
Kids
King
2. Phylum
Play
Phillip
We now have 6
Kingdoms
3. Class
Catch
Came
including
4. Order
Over or Over
Bacteria, Fungi,
and Protists.
5. Family
Farmer
For
6. Genus
Grays
Grape
7. Species
Shed
Soda
Scientific Names
• Scientific names are made of two words:
– Genus & species.
• Genus is always capitalized
• Species is not
• The scientific name should always be in italics
or underlined.
Homo sapien
Example of Scientific Name
• Common name: Cat
• Scientific name: Felis domesticus
– Genus: Felis
– Species: domesticus
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
Order: Carnivora
Family: Felidae
Genus: Felis
Species: Felis domesticus
Human’s Classification
Kingdom
Phylum
Class
Order
Family
Genus
Species
Animalia
Chordata
Mammalia
Primates
Homindae
Homo
Sapiens
Cladogram
• Shows evolutionary
relationships between
animals.
• Shows how closely
related two animals are.
Dichotomous Key
• A list of
characteristics,
such as structure
and behavior,
organized in such a
way that organisms
can be identified.
Pick one object
1a. With a hole Go to Question 2
1b. Without a hole Go to Question 3
2a. Six sided It is Species #1
2b. Four sided It is Species #6
3a. With threading Go to Question 4
3b. Without threading It is Species #8
4a. Pointy tip Go to Question 5
4b. No pointy tip Go to Question 6
5a. Rounded head It is Species #4
5b. Not rounded head It is Species #7
6a. Flat head Go to Question 7
6b. Not flat head It is Species #2
7a. Body length twice the width of
head It is Species #5
7b. Body length not twice the width
of head It is Species #3
Which animal is most
closely related to
the grizzly bear?
Which animal is the
least related to the
grizzly bear?