Division Ave. High School
Ms. Foglia
AP Biology
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500
Millions of years ago
1000
Origin of Life
1500
2000
2500
3000
3500
Cenozoic
Mesozoic
Paleozoic
ARCHEAN
PROTEROZOIC
PRECAMBRIAN
“…sparked by just the right
combination of physical events
& chemical processes…”
4000
AP Biology
2007-2008
What is Life?


organized as cells
respond to stimuli
regulate internal processes

use energy to grow

develop
 change & mature
within lifetime


 heredity
 DNA / RNA
 adaptation & evolution

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Conditions on early Earth
 Reducing atmosphere
water vapor (H2 O), CO2 , N2 , NOx , H2, NH3 ,
CH4, H2S
 lots of available H & its electron
low O2 =
 no free oxygen


lightning, UV radiation,
volcanic
Oldest definite fossils
of prokaryotes
Molten-hot surface of
earth becomes cooler
Formation of earth
The evolutionary tree of
life can be documented
with evidence.
The Origin of Life on
Earth is another story…
Was life created by a
supernatural or divine force?
not testable
Was the original source of
organic (carbon) materials
comets & meteorites striking
early Earth?
testable
organic molecules
do not breakdown
as quickly
Did life evolve spontaneously
from inorganic molecules?
testable
Oparin and Haldane 1920s
 Oparin- Russia/ Haldane-Great Britain
 Hypothesized steps of chemical
evolution from primitive earth
conditions.
 The ancient world had energy and
resources for abiotic synthesis of
organic molecules
What’s missing
from that
atmosphere?
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Appearance of oxygen
in atmosphere
 Spontaneous Abiotic Origin
reproduce
 Energy source
Oldest definite fossils
of eukaryotes
 Extraterrestrial Origin
 metabolism

Animalia
 Special Creation

 homeostasis

Bacteria Archae- Protista Plantae Fungi
bacteria
The Origin of Life is Hypothesis
 First we have to define LIFE…

4500
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Colonization of land
by animals
Appearance of animals
and land plants
First multicellular
organisms
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Division Ave. High School
Ms. Foglia
AP Biology
Electrodes discharge
sparks
(lightning simulation)
Origin of Organic Molecules
 Abiotic synthesis
1920
Oparin & Haldane
propose reducing
atmosphere
hypothesis
 1953
Miller & Urey
test hypothesis

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 formed organic
compounds
 amino acids
 adenine
Water vapor
CH4
NH3
Mixture of gases
("primitive
atmosphere")
University of Chicago
H2
Condenser
Water
Heated water
("ocean")
Four Stage Hypothesis for Origin of Life
“Science seeks natural causes for natural phenomenon”
1. Monomer Formation
Stanley Miller
Condensed
liquid with
complex,
organic
molecules
produced
-amino acids
-hydrocarbons
-nitrogen bases
-other organics
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1. Monomer Formation
 What were conditions on early earth?
 What experiments showed how
monomers might have formed?
2. Polymer Formation
 Where else on earth could monomers
have formed?
3. Origin of Heredity
4. Protobiont Formation
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2. Polymer Synthesis
 Problem:


Monomers dilute in concentration.
No enzymes for bond formation.
Dawn of natural selection
3. Origin of Genetics
 RNA is likely first genetic material


 self-replicating molecule
 makes inheritance possible
 natural selection & evolution
Possible Answer
Polymerization in lab on:
1. Clay
2. Iron Pyrite

enzyme functions
 ribozymes
 replication


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multi-functional
codes information
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regulatory molecule
transport molecule
 tRNA & mRNA
Division Ave. High School
Ms. Foglia
AP Biology
Protobiont Formation
4. Origin of Cells (Protobionts)
Aggregates of abiotically produced
molecules.
Exhibit some properties of life.
Ex: Osmosis, Electrical Charge,
Fission
 Proteinoid: chain of amino acids
with weak catalytic activity
Proteinoids + H2 O  microspheres
Liposomes: spherical particle formed
by lipid bilayer
Liposomes + H2O  lipid membranes
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Protobionts: Coacervates
 Colloidal droplets of proteins, nucleic
acids and sugars surround by a water
shell.
 Will form spontaneously from
abiotically produced organic
compounds.
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evolutionary
history of life on
Earth
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synthesis come from?
 Submerged Volcanoes/ Deep sea vents
 Colonization of Earth from meteorites
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Key Events in Origin of Life
 Key events in

Other Ideas:
 Where did chemicals for organic
life originated
3.5–4.0 bya
Prokaryotes
 Prokaryotes dominated life
on Earth from 3.5–2.0 bya
3.5 billion year old
fossil of bacteria
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modern bacteria
chains of one-celled
cyanobacteria
Division Ave. High School
Ms. Foglia
AP Biology
Lynn Margulis
Stromatolites
Oxygen atmosphere
 Oxygen begins to accumulate 2.7 bya
Fossilized mats of
prokaryotes resemble
modern microbial
colonies

 evidence in banded iron in rocks = rusting
 makes aerobic respiration possible


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~2 bya

photosynthetic
algae)
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First Eukaryotes
 Development of internal membranes

reducing → oxidizing atmosphere
create internal micro-environments
advantage: specialization = increase efficiency
infolding of the
plasma membrane
endoplasmic
reticulum (ER)
plasma
membrane
Endosymbiosis
 Evolution of eukaryotes


nuclear envelope

nucleus
origin of mitochondria
engulfed aerobic bacteria,
but did not digest them
mutually beneficial relationship
internal membrane
system
aerobic bacterium
mitochondrion
DNA
Endosymbiosis
cell wall
Prokaryotic
cell
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Prokaryotic
ancestor of
eukaryotic
cells
plasma
membrane
Endosymbiosis
 Evolution of eukaryotes



Eukaryotic
cell
Ancestral
cell
AP
Biology
eukaryotic
Eukaryotic
cell with
mitochondrion
origin of chloroplasts
engulfed photosynthetic bacteria,
but did not digest them
mutually beneficial relationship
Theory of Endosymbiosis
 Evidence



Eukaryotic cell with
& mitochondrion
genetic
Lynn Margulis
 mitochondria & chloroplasts
have their own circular DNA, like bacteria
chloroplast
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chloroplast
structural
 mitochondria & chloroplasts
resemble bacterial structure
photosynthetic
bacterium
Endosymbiosis
Eukaryotic cell
with mitochondrion
mitochondrion
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functional
 mitochondria & chloroplasts
move freely within the cell
 mitochondria & chloroplasts
reproduce independently
from the cell
Division Ave. High School
Ms. Foglia
AP Biology
Cambrian explosion
 Diversification of Animals

within 10–20 million years most of the major
phyla of animals appear in fossil record
543 mya
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Diversity of life & periods of mass extinction
Cambrian
explosion
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Cretaceous extinction
The Chicxulub impact crater in the
Caribbean Sea near the Yucatan
Peninsula of Mexico indicates an
asteroid or comet struck the earth and
changed conditions 65 million years ago
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Early mammal evolution
 125 mya mammals
began to radiate
out & fill niches
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Division Ave. High School
Ms. Foglia
AP Biology
Classifying Life
 Molecular data
3 Domain system
 Domains = “Super” Kingdoms
challenges 5 Kingdoms

 Monera was too diverse
 2 distinct lineages of prokaryotes
 Protists are still too diverse
 not yet sorted out

Bacteria
Archaea
 extremophiles = live in extreme environments
 methanogens
 halogens
 thermophiles

Eukarya
 eukaryotes
 protists
 fungi
 plants
 animals
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Any Questions??
Is there life elsewhere?
Does it look like life on Earth?
Kingdom
Bacteria
Kingdom
Archaebacteria
Kingdom
Protista
Kingdom
Kingdom
Plantae
Kingdom
Animalia
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