Transcript Mod 2: Ch15 Set 1

MODULE 2: Slide Set 1
Chapter 15
Origin of Life, Eukaryotes and Multicellularity

Read Ch 15 and do the activities at “Mastering Biology”
Chapter 15
Life’s Origin and Early History
 Spontaneous Generation
 Abiogenesis




Oparin/Haldane: “chemical evolution hypothesis”
Stanley Miller: Abiotic synthesis…
Biogenesis



Early stages
Lynn Margulis: Endosymbiosis
Origin of Multi-celled organisms
The 4 Paradigms of Modern Biology
(you could actually make this 3)
1. Evolutionary Theory
R 2. Cell Theory
o 3a. Biology obeys the laws of physics and chemistry for matter
R 3b. Biology obeys the laws of physics and chemistry for energy
R
in vivo
vs.
in vitro
Biology and Society:
Can Life Be Created in the Lab?


How did life first arise on Earth?
To gain insight, scientists have recently (2010)
• Synthesized the entire genome of Mycoplasma
genitalium, a species of bacteria found naturally in the
human urinary tract
• Transplanted the complete genome of one species of
Mycoplasma bacteria into another
© 2010 Pearson Education, Inc.

A research group led by Craig Venter hopes to has
• Created an artificial genome
• Transplanted it into a genome-free host cell

An artificial organism that could be completely
controlled might:
• Clean up toxic wastes
• Generate biofuels
• Be unable to survive outside rigidly controlled
conditions
Figure 15.00
MAJOR EPISODES IN THE HISTORY OF
LIFE


Earth was formed about 4.6 billion years ago.
Prokaryotes
•
•
•
•


Evolved by 3.5 billion years ago
Began oxygen production about 2.7 billion years ago
Lived alone for almost 2 billion years
Continue in great abundance today
Single-celled eukaryotes first evolved about 2.1
billion years ago.
Multicellular eukaryotes first evolved at least 1.2
billion years ago.
Major episodes in History of Life
Precambrian
Common ancestor to
all present-day life
Origin of
Earth
4,500
Earth cool enough
for crust to solidify
4,000
Atmospheric oxygen
begins to appear due
to photosynthetic
prokaryotes
Oldest prokaryotic fossils
3,500
3,000
2,500
Millions of years ago
Figure 15.1a
Paleozoic
Precambrian
Mesozoic
Cenozoic
Archaea
Fungi
Animals
Cambrian
explosion
Oldest eukaryotic
fossils
2,000
Origin of
multicellular
organisms
1,500
Oldest
anim
al
fossils
1,000
Plants and
symbiotic fungi
colonize land
Extinction of
dinosaurs
First humans
500
0
Millions of years ago
Figure 15.1b
Eukaryotes
Protists
Plants
Prokaryotes
Bacteria


All the major phyla of animals evolved by the
end of the Cambrian explosion, which began
about 540 million years ago and lasted about 10
million years.
Plants and fungi
• First colonized land about 500 million years
• Were followed by amphibians that evolved from fish

What if we use a clock analogy to tick down all of the
major events in the history of life on Earth?
Origin of Life: first prokaryotes
~3.5 byp
Photosynthesis and atmospheric oxygen appear ~2.7 byp
Single-celled eukaryotes ~2.1byp
Multicellular eukaryotes ~ 1.2 byp
Animals ~0.54 byp
Colonization of land ~0.5 byp
Homo habilis ~ 0.0024 byp
THE ORIGIN OF LIFE

We may never know for sure how life on Earth
began.
Resolving the Biogenesis Paradox




All life today arises by the reproduction of preexisting life, or
biogenesis.
If this is true, how could the first organisms arise?
From the time of the ancient Greeks until well into the 19th
century, it was commonly believed that life regularly arises
from nonliving matter, an idea called spontaneous
generation.
spontaneous generation vs abiogenesis vs biogenesis
The 4 Paradigms of Modern Biology
(you could actually make this 3)
1. Evolutionary Theory
R 2. Cell Theory
o 3a. Biology obeys the laws of physics and chemistry for matter
R 3b. Biology obeys the laws of physics and chemistry for energy
R
in vivo
vs.
in vitro
vitalists vs mechanists
(mechanists become reductionists)
.
Reductionists say: the processes of life can be
explained by the laws of physics and chemistry.
 in vivo (in life)
 in
vitro (in “glass”)
“Spontaneous Generation”
The idea that life can arise spontaneously
from non-living things.
Francisco Redi
Needham, Spallanzani, Pasteur
 Life

DOES NOT arise spontaneously
Pasteur: “Never will the concept of spontaneous generation recover
from the mortal blow of my simple experiments.”
A.I. Oparin and J.B.S. Haldane
Biogenesis
The Idea of Chemical Evolution
Freidrich Wöhler, 1828
"I cannot, so to say, hold my chemical water and must tell you
that I can make urea without thereby needing to have kidneys,
or anyhow, an animal, be it human or dog".
Fermentation
Hans und Eduard
Buchner
electrodes
First
Atmosphere
to
vacuum
pump
CH4
NH3
H2O
H2
spark
discharge
gases
water out
condenser
water in
water droplets
boiling water
water containing
organic compounds
liquid water in trap
“Ur-atmosphere”
NO OXYGEN
NO OXYGEN
NO OXYGEN
An iconic
experiment.
We have
alternate revised
hypotheses
today.
Fig. 20-4c, p.321
Jeffrey Bada, Nazi Syn-fuels
S.M. 1953. 5 AA’s; J.B. 2008, 22 AA’s
•So… life arises on the primitive Earth quickly... 400
million years at most.
Earth is anaerobic, NO OXYGEN.
Life is entirely prokaryotic in the beginning.
Prokaryotes dominate for half of life’s history; in truth,
they dominate today.
But we also have the Eukarya today. Where did they
come from???
We need evolution of eukaryotes AND we need
evolution of multicellularity.
We’ll come back to that. First a survey of Life…
What are the kinds of life?
What are the kinds of living “things” we find
on our planet???
There are lots of useful ways
to classify life
 Phylogenetic
Classification
 Ecological Classification
 Spatial/Lifestyle Classification
Phylogenetic classification is based
on evolutionary relationships.
PHYLOGENETIC CLASSIFICATION
 Phylogenetic
classification is classification
based on phylogeny, i.e. evolutionary
relationships.
 Organisms are placed in a group because,
as best we can tell, they are related
evolutionarily.
 So phylogenetic classification puts bats
and whales in the same group (Mammals)
and in a different group than fish or birds.
The Three Domains
PHYLOGENETIC CLASSIFICATION
Who’s related to whom?
Biology’s gigantic Maury Povich Show
The 3 Domains, Carl Woese
1967, 1990
Domains are the largest taxa !
There are 3 domains. These are based in
similarities and differences in ribosomal RNA.
The Domains are sometimes
divided into 6 Kingdoms
Protistans
Plants
Fungi
Animals
Eukaryotes
Archaebacteria
Eubacteria
Origin of life
Phylogenetic Classification
(based on phylogeny, i.e. evolutionary relationships)
The 3 Domain System is replacing
the 6 Kingdom system.
(But who cares if the big shots are
“rearranging the furniture” upstairs?)
We will be using the 6 kingdom
system for ease of communication
and to get us to the (lowly?)
animals… the things this course is
supposed to be about.
What are the kinds of living things on Earth?
ECOLOGICAL CLASSIFICATION
energy input,
from sun
Prodcers
(plants, and other selffeeding organisms)
Nutrient
Cycling
Consumers
Animals, most fungi, many
protists, many bacteria
energy output (mainly metabolic heat)
Fig. 1-3, p.6
Ecological Classification
Based on organism’s role in the ecosystem

AUTOTROPHS (Producers or Primary Producers)
 HETEROTROPHS


Consumers
Decomposers
Autotrophs and Heterotrophs
Producers, Consumers, Decomposers
Energetics
autotrophic vs. heterotrophic
PHOTOSYNTHESIS
H2O +
Water +
light energy
CO2
enzymes
Carbon
Dioxide
C6H12O6 + O2
Glucose + Oxygen
RESPIRATION
C6H12O6
Glucose +
+
O2
Oxygen
H2O +
Water +
CO2
Carbon
Dioxide
p.111
Systems of Classification
 “Spatial”/”Lifestyle”



Plankton
Nekton
Benthos
Classification
Domain Bacteria
Domain Archaea
Earliest
life
The protists
(multiple kingdoms)
Kingdom
Plantae
Domain Eukarya
Kingdom
Fungi
Kingdom
Animalia
Figure 14.25
We will concentrate on the 6 kingdoms !
So…
How do we distinguish among the six kingdoms?
Cell Number


unicellular vs. multicellular
Cell Type


prokaryotic vs. eukaryotic
Energetics


autotrophic vs. heterotrophic
Cell Number
unicellular vs. multicellular
Cell Type
prokaryotic vs. eukaryotic cells
Cell Type
prokaryotic vs. eukaryotic cells
 karyon
gk. “kernel of corn”
 Prokaryotic cells are:



Simpler, smaller, less specialized, less compartmentalized.
Most-notably, they lack a nucleus (and mitochondria, etc.)
Bacteria (=Eubacteria), Archaea (=Archaebacteria)
 Eukaryotic



cells are:
More complex, more specialized, compartmentalized
They have a well-defined nucleus (and mitochondria, etc.)
Domain Eukarya
• Protista, Fungi, Plantae Animalia
Energetics
autotrophic vs. heterotrophic
 Autotrophs



produce their own food
Photosynthesis, chemosynthesis
Also called producers or primary producers
Some bacteria, some protists, “all” plants
 Heterotrophs



do not make food
They have to eat some other organism
Consumers and decomposers
Some bacteria, some protists, animals, fungi
Energetics
autotrophic vs. heterotrophic
PHOTOSYNTHESIS
H2O +
Water +
light energy
CO2
enzymes
Carbon
Dioxide
C6H12O6 + O2
Glucose + Oxygen
RESPIRATION
C6H12O6
Glucose +
+
O2
Oxygen
H2O +
Water +
CO2
Carbon
Dioxide
p.111
C’s and H’s and O’s
rearrange to make
C’s and H’s and O’s
!!!
Carbon dioxide and Water make Sugar and Oxygen
and then…
Sugar and Oxygen make Carbon dioxide and Water.
and then…
Carbon dioxide and Water make Sugar and Oxygen
and then…
Sugar and Oxygen make Carbon dioxide and Water
So, what’s up with that?
It’s all about the
Big E
Biggie, R.I.P. How does he do that?
What fuels him?
THE SIX KINGDOMS OF LIFE
KINGDOM
BACTERIA
ARCHAEA
PROTISTA
FUNGI
PLANTAE
ANIMALIA
UNI / MULTI
PRO / EU
AUTO / HETERO
THE SIX KINGDOMS OF LIFE
KINGDOM
UNI / MULTI
PRO / EU
AUTO / HETERO
BACTERIA
UNI
PRO
A/H
ARCHAEA
UNI
PRO
A/H
PROTISTA
UNI / MULTI
EU
A/H
FUNGI
UNI / MULTI
EU
H
PLANTAE
MULTI
EU
A
ANIMALIA
MULTI
EU
H
EUBACTERIA
the “true” bacteria
Archaea, the “extremophiles”
methanogens, thermophiles, halophiles
THE PROTISTA
a polyphyletic kingdom, “fer shure”
KINGDOM FUNGI
mushrooms, mold mildew, yeasts
heterotrophic uni / multi, eukaryotes
KINGDOM PLANTAE
autotrophic, multicellular, eukaryotes
KINGDOM ANIMALIA
Heterotrophic, multicellular, eukaryotes
Fig. 1-8c(10), p.9
Fig. 19-19, p.314
living
cells
membrane-bound proto-cells
self-replicating system enclosed in a
selectively permeable, protective lipid sphere
DNA
RNA
formation of
protein-RNA systems,
evolution of DNA
enzymes and
other proteins
formation of
lipid spheres
spontaneous formation of lipids,
carbohydrates, amino acids, proteins,
nucleotides under abiotic conditions
Stepped Art
Fig. 20-7c, p.323
The Golden Age of Prokaryotes
 Archaean
Eon: 3.8-2.5 BYP
Fig. 20-7, p.324
Rise of Eukaryotes
The Oxygen Revolution
 About
2.5 BYP PHOTOSYNTHESIS !
 The Oxygen Revolution had 2 irreversible
effects:


Abiogenesis shut down by oxygen !
Aerobic Respiration evolves and makes
“getting energy” from food much more
efficient !!
Fig. 20-7, p.324
Theory of Endosymbiosis

Lynn Margulis (our old friend from week 2) says…

Mitochondria and chloroplasts are the descendents of freeliving prokaryotic organisms

Prokaryotes were engulfed by early eukaryotes and became
permanent internal symbionts.

Oh yeah sure! This one eats that one and that one eats this one
and then this one becomes a part of that one and then you got,
like, you know, people???

You have some evidence for that?

Well, I’m glad you asked.
Zooxanthellae, Zoochlorellae, Zoocyanellae
symbiotic algae living inside various animals is common in biology
Mitochondrial DNA
Chloroplast DNA
Bacterial DNA
hydrogen-rich anaerobic atmosphere
atmospheric oxygen, 10%
archaean
lineage
d
ancestors of
eukaryotes
h
endomembrane
system and nucleus
cyclic pathway
of photosynthesis
e
a
noncyclic pathway
of photosynthesis
f
b
origin of
prokaryotes
3.8 billion
years ago
g aerobic respiration
3.2 billion
years ago
2.5 billion
years ago
Fig. 20-12a, p.328
atmospheric oxygen, 20%; the ozone layer slowly develops
k origin of animals
j
origin of eukaryotes,
the first protists
i
endosymbiotic origin
of mitochondira
j
endosymbiotic origin
of chloroplasts
k origin of fungi
k origin of lineage
leading to plants
Aerobic species becomes endosymbiot of
anaerobic forerunner of eukaryotes.
1.2 billion
years ago
900 million
years ago
435 million
years ago
Fig. 20-12b, p.328
Multicellularity
Evolution of Multicellularity
Evolution of Multicellularity
An experiment that yielded proto-bodies from no-bodies

A single-celled alga cultured in the lab for more than a thousand
generations.
 Always single-celled.
 Introduce a single-celled predator that feeds on this alga.
 In <200 generations the alga:



Becomes clumps of hundreds of cells
Over time the clumps drop to 8 cells
Eight turns out to be optimum size of clump to:


1) Avoid being eaten
2) While maximizing light availability to all cells

When predator was removed it remained an 8-cell colony!
 Proto-bodies evolved from “no-bodies” in a couple of hundred generations.
Borass, M. E. Seale, D.B., Boxhorn, J. 1988. Phagotrophy by a flagellate selects for
colonial prey: A possible origin of multi-cellularity. Evolutionary Ecology, 12:153-164.
The Cambrian Explosion
about 530 MYBP
The Burgess Shale (British Columbia, Canada) & The Ediacaran Fauna of Australia
Mass Extinctions !
(left over from Ch 14)
Great fun, unless of course you’re in one. The biological deck get cleared,
the biosphere changes, there is burst of evolution.
The K/T Boundary
65 million years ago
see p. 284


Iridium-rich sedimentary layer.
Luis (dad, physicist) and Walter (son, geologist) Alvarez
The Iridium Anomaly in the
KT Boundary Sediments
•This
is best picture I could find.
•It’s my understanding that
average Ir was 100 ppm and
peak was 3000ppm.
•That’s 30X higher at Gubbio
•Denmark:
•But
160X, New Zealand: 20X
you get the picture !!!
K/T Boundary
Foraminifera prior to K-T
boundary
Foraminifera from after K-T
boundary
The K/T Boundary
65 million years ago
fun with asteroids: click here and get blown away
Mass Extinctions

Have been major contributors to evolutionary
upheavals.
 Survive or not survive in a changed world.
 Gradualism? Catastrophism? Both?
Yet another Big E !!
UNIT 2 Slide Set 1
END
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