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Classification & Origin of Life
AP Biology
Unit 4
Characteristics of Life
1.
2.
3.
4.
5.
Metabolism, Growth, & Development
Reproduction
Response to Environment
Genetic Information that can be passed
on, evolution
Physical order/ highly ordered system
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Is fire living?
NO
Is a virus living?
NO
Is a prion living?
NO
Origin of Life on Earth
• Scientific evidence indicates that Earth
formed 4.6 billion years ago (bya)
• First evidence of life on Earth is from
fossils that are 3.5 billion years old.
• There are multiple theories and models
about how living things/cells may have first
appeared.
General Sequence of Events
• Small organic molecules (like amino acids
and nucleotides) form from abiotic factors.
• Small organic molecules join together into
biomolecules that can replicate, store and
transfer info
• Molecules become surrounded by a
membrane – “protobionts”
• Cellular processes develop
Oparin-Haldane Hypothesis (1920s)
• Hypothesis about how early organic
compounds were synthesized
• Said Earth had a reducing atmosphere
– CH4, NH3, and H2 present in atmosphere (no
O2)
– H2O in ocean
– Electricity added (provided electrons) –
lightning
 This would produce fatty acids and amino
acids
Miller-Urey
Experiment
• Tested the
OparinHaldane
hypothesis
• Found a
variety of
amino acids in
the solution
Additional Experiments
• Oro (1961)
• Repeated experiments similar to MillerUrey
– Produced amino acids, sugars, nucleotides
• All of these experiments show it is possible
to synthesize organic molecules from
abiotic sources.
“RNA World” Hypothesis
• Proposes that RNA was the first
genetic material (not DNA).
• self-replicating RNA carried out
catalytic activities (because no
protein or DNA yet)
• RNA found to have many
catalytic properties that support
this hypothesis:
– ex. microRNAs
– ex. Ribozymes (RNA catalysts),
Ribosomes
Classification Method:
5 Kingdoms
• Monera (Prokaryotes)
• Protista
– Euglena, Amoeba, etc.
• Plantae
• Fungi
• Animalia
Classification: 3 Domains
• 3 Domains are Bacteria, Archaea, Eukarya
 Monera Kingdom is divided into Bacteria and
Archaea
 Branching pattern is based on rRNA sequence
comparison
 Former branching pattern based on behavior
placed Archaea as most related to the Origin of
Life (hence the name Archaea)
Eukaryotes
Presumed Development of
Ancestor of Eukaryotes
Endosymbiosis happens
(chloroplasts)
Endosymbiosis happens
(mitochondria)
Ancestor of eukaryotic
cells (mixture of bacteria
and archaea)
Earliest common ancestor
of all living things
Domains
• Bacteria
– Unicellular
– Live at moderate environments
– Prokaryotes
• Archaea
– Unicellular
– Live at extreme environments (temperature,
salinity, etc)
– Prokaryotes
Domains
• Eukarya
– Multi or unicellular
– Eukaryotes
Endosymbiont
Hypothesis
 describes the evolution
of eukaryotes (presence
of organelles) from
prokaryotes
 occurred at least 2.1
billion years ago
Evolution of Colonies
• Colonies evolved before
multicellular organisms
• Important for the eventual
evolution of multicellularity
 multicellularity occurred at
least 1.5 billion years ago
• Benefits of colonies?
– Shared tasks but each organism
is independent
Pangaea
 all continents were once connected
(250 million years ago)
 explains relatedness between
geographically isolated organisms
• ex: Ichthiosaurs in NE Oregon’s
Blue Mountains and China
• plate movement continues today!
Classification Overview
• Cell Types:
– Prokaryotes
• No nucleus
• No cytoskeleton
• No Membrane-bound organelles
– Eukaryotes
• Both unicellular and multicellular
• Nuclei, cytoskeleton, and organelles present
Monera
Fun fact:
There are more
bacteria living in you
than your own body
cells!

Monera
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Bacteria (Prokaryotes)
Unicellular
Most have a cell wall
Can be photosynthetic
Protista
Fun Fact:
Euglena
“Red tide” is caused by
reddish colored protists
that grow too fast and
make the ocean look
pinkish.
Amoeba
Protista
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Mostly Unicellular
Many are colonial
Can be motile
Can be photosynthetic (autotrophs)
Some have a cell wall
Fungi
Fun fact:
The largest living organism might
be a fungus– it is a species of
Armillaria bulbosa that is around
1500 years old and extends
across 35 acres of land in
northern Michigan!
Fungi
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Unicellular or Multicellular
Eukaryote
Non-motile
Heterotrophs– NO PHOTOSYNTHESIS
Have a cell wall
Plantae
Carnivorous Plant
Fun Fact:
Rafflesia
arnoldii is the
largest flower in
the world
• It can grow up
to 3 feet across
and weigh 15
pounds
• It emits a smell
similar to rotting
meat
Plantae
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Multicellular
Autotrophs
Non-motile
Eukaryotes
Have a cell wall (cellulose)
Animalia
Fun Fact:
The African
porcupine has
quills that are
about a foot long
and ¼ inch in
diameter.
Animalia
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Multicellular
Heterotrophs
Eukaryotes
Most are motile
No cell wall