Honors Diagram

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Honors Diagram
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Synopsis

• This course will study the origin and
  development of life on the planet Earth within
  the context of an evolving universe. We review
  the origins of the universe from the "Big Bang"
  to our own solar system and integrate the
  principles of physics, chemistry, geology and
  biology to study the origins of life on Earth.
  We address the ultimate fate of life in the
  universe based upon our understanding of
  thermodynamics, expansion of the universe, and
  properties innate to all living systems.

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Synopsis Continued

The essential features of all living systems are
discussed as they relate to what we might expect
in terms of life elsewhere in the universe.
This analysis is based on features of living
systems on Earth (plant, animal and microbe),
including those from very extreme environments
(extremophiles).
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Synopsis Continued

• The labs are an integral part of the course and
  include computer simulations and hands-on
  experiments to demonstrate essential features of
  the (i) origins of the universe, (ii) life on the
  planet Earth, (iii) search for life on Earth and
  elsewhere in the universe, and (iv)
  extraterrestrial space travel and exploration.

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Astrobiology Week 2 Lecture

• Universe of Life? (Chapter 1)
• Recapitulate last week
• Universality of biology
• New science of astrobiology
• Life in the Universe From Speculation to
  Science (Chapter 2)
• History of speculation
• Transition to the science
• Revolution in the Physical Sciences Copernicus
• Revolution in the Geological Sciences Wegener
• Revolution in the Life Sciences Darwin, Mendel,
  Watson and Crick
• Nature and Methods of Science (Chapter 2 Geller)

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Universality of Chemistry and Physics?

• Laws of physics are universal?
• What do we mean by universal?
• What do we mean by Laws of physics?
• How do we know they operate in the universe?
• Conclusion
• Laws of chemistry are universal?
• What do we mean by universal?
• What do we mean by Laws of chemistry?
• How do we know they operate in the universe?
• Conclusion

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Universality of Biology?

• Characteristics (laws?) of biological systems
  universal?
• What do we mean by universal?
• What do we mean by characteristics of biological
  systems?
• How do we know they operate in the universe?
• Conclusion?

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Historical Debate on Life in Other Worlds
Speculation

• Mythology (lt 600 BC)
• Atomists (600 BC 400 BC)
• Aristolelians (400 BC 300 BC)
• Christianity (Middle Ages)
• Transition Speculation to Science
• Copernican Revolution
• Revolution in the Life Sciences and Geology
• Summary role of science versus speculation

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Revolution in the Sciences and Question of Life
in Universe

• The process of change (speculation to science)
• Change in human perspective (stars are just not
  lights but other worlds)
• Idea of extraterrestrial life
• Universality of Laws of physics
• Universality of Laws of chemistry
• Dynamic state of Earths geology
• Rise of the life sciences (from Darwin to
  bioinformatics)
• Universality of characteristics of living systems
  (?)

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Astrobiology The Nature of Life(Chapter 3)

• Properties of Living Systems
• Evolution as a Unifying Theme
• Structural Features of Living Systems
• Biochemical and Molecular Features of Living
  Systems
• Instructional Features of Living Systems
• Evolution as a Unifying Theme
• Extremophiles on Earth and Elsewhere
• Define Life (homework assignment and rappateur
  session)

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Properties of Living Systems

• Not laws
• From Bennett et al.
• Order (hierarchy)
• Reproduction
• Growth and development
• Energy use
• Response to the environment (open systems)
• Evolution and adaptation

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Properties of Living Systems

• From Taylor
• Hierarchical organization and emergent properties
• Regulatory capacity leading to homeostasis
• Diversity and similarity
• Medium for life water (H2O) as a solvent
• Information Processing

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Properties of Living Systems Regulatory Capacity

• Define regulatory capacity
• Relate to open systems
• Define homeostasis
• Role of feedbacks (positive and negative) and
  cybernetics
• Why is regulatory capacity and homeostasis and
  important property of living systems?
• Examples
• Molecular biology gene regulation
• Biochemistry enzymes
• Organisms temperature
• Globe Parable of the Daiseyworld

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Structural Features of Living Systems (continued)

• Evolution of cell types
• Prokaryotes
• Cell, membranes but no nucleus
• Examples bacteria
• Eukaryotes
• Cell, membrane, and nucleus
• All higher plants and animals
• Evolution of cell types
• Points to a common ancestor

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Molecular Features of Living Systems

• Genes and genomes
• Replication of DNA
• Transcription, translation, and the genetic code
• Polypeptides and proteins
• Biological catalysis enzymes
• Gene regulation and genetic engineering
• Points to a common ancestor

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NASAs Definition of Life

• System possessing the ability of maintaining
  form and function through feedback processes in
  face of a changing environment, resulting in
  homeostasis Chris McKay
• Key Points in definition
• Maintaining function
• Feedback Processes
• Changing environment
• Homeostasis

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Origin and Evolution of Life on Earth (Week 5)

• Searching for the origin
• Functional beginnings of life
• Focus on enzymes (lab)
• From chemistry to biology at the molecular level
• Prokaryotes and oxygen
• Eukaryotes and explosion of diversity
• Mass extinctions, asteroids and climate change
• Evolutions of humans (what a bore!)
• Conclusions

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Searching for the Origin

• Domain Domain
  Domain
• Bacteria Archaea
  Eukarya
• Common
• Ancestor

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Beginnings of Life on Earth

• Organic chemistry
• Transition from chemistry to biology
• Panspermia
• The evolution of sophisticated features of
  metabolism and information brokers
• Conclusions
• _________
• Enzymes first

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Catalysis in Living Systems Enzymes

• Introduction
• Most reactions are very, very slow (not
  sufficient to sustain life)
• Mechanisms to accelerate specific reactions
  preferential acceleration
• Evolutionary significance positive fitness
• Accelerants Catalysts Enzymes
• Proteins (relate to information brokers)
• Change rate of reactions
• High degree of specificity
• Regenerated (not consumed)

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Ribozymes

• What are ribozymes in current biochemistry?
• NOT ribosomes
• mRNA (small fragments)
• Functions
• Synthesis of RNA, membranes, amino acids,
  ribosomes
• Properties
• Catalytic behavior (enhance rates 20 times)
• Genetically programmed
• Naturally occurring (60-90 bases)

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Urey-Miller Experiment
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Functional Beginnings of Life Transition from
Chemistry to Biology

• Evolution of Photosynthesis
• CO2 H2O Light CH2O O2
• Key processes
• Absorption of light (pigments)
• Conversion of light energy into chemical energy
  (ATP)
• Synthesis of simple carbon compounds for storage
  of energy
• Purple bacteria and Cyanobacteria
• Primitive forms (3.5 BYA)

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Prokaryotes and Oxygen
of Present
4.8 4 3 2 1
0.7 0.1 0
Billions of Years Before Present
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Eukaryotes and an Explosion of Diversity

• Incremental changes in evolution role of oxygen
  and diversification of organisms (explain ATP
  fitness)
• Quantum changes in evolution
• Symbiosis
• Lynn Margulis theory eukaryotes are derived from
  prokaryotes
• Compartmentalization and organelles
• Bacterial origins of chloroplast and mitochondria

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Mass Extinctions, Asteroids and Climate Change

• Mass extinctions
• Dramatic declines in a variety of species,
  families and phyla (gt25)
• Timing of decline is concurrent
• Rate of decline is precipitous (geological sense)
• Example of catastrophism
• Best example
• Cretaceous/Tertiary boundary (65 M years ago)
• K-T boundary and Alvarez theory of catastrophism

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Origin and Evolution of Life on Earth Conclusions

• Plausible scenario for the early origin of life
  on Earth (abiotic and biotic)
• Role of mutation and evolution in origin of
  increasingly more complex forms of metabolism
• Role of major evolutionary and climatological
  events in pulses of diversification in biota

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Searching for Life in Our Solar System Chapter 6

• Introduction
• Environmental requirements of life
• Elements of the periodic table
• Energy for metabolism
• Liquid solution for living systems
• Concept of habitability zones
• Passing the baton to Professor Geller

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Energy for Metabolism

• Introduction
• Sunlight and photochemical energy
• Energy decreases with square of distance from
  source (e.g., Sun)
• Example leaf on Earth versus leaf twice as far
  out from Earth (1/4 as much energy)
• Example 10 times further out, energy would be
  1/102 or 0.01times as much

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Liquid Solution for Living Systems

• Introduction
• Life on Earth in water.4 BYA
• First 3 BY of life in water alone
• All life tied to watery medium (plants, animals
  and microbes)
• Habitability of Earth f water
• Simplicity and complexity of the nature of the
  water molecule
• Deceptively simple in structure
• Exquisite in function

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Water and Its Properties Polarity

• Composition and structure a polar molecule
• Features
• Attraction is electrical
• Hydrogen bonding among two molecules of H2O
• Exquisite properties of H2O arise from chemical
  attractions because it is a polar molecule
  emergent properties

H
O
H
-
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Habitability Principle and Application to
Astrobiology

• Introduction
• Concept of habitability zone
• Comparative habitability of the terrestrial
  planets
• Parable of the Daiseyworld (laboratory)
• Factors that underpin habitability
• The Suns habitability zone
• Habitability outside our Solar System

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Habitability Introduction

• Define habitability
• Anthropocentric perspective
• Astrobiological perspective (capable of harboring
  liquid water)
• Key physical and chemical features of
  habitability
• Surface habitability
• Temperature
• Source of energy
• Liquid water (present and past)
• Biological macromolecules (e.g., sugars,
  nucleotides)
• Atmosphere and magnetosphere

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Concept of a Habitability Zone

• Definition of habitability zone (HZ)
• Region of our solar system in which temperature
  allows liquid water to exist (past, present and
  future)
• Phase diagram for H2O
• Retrospective analysis of HZ using the
  terrestrial planets as case study
• Mars, Venus and Earth
• Prospective analysis of HZ

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Comparative Habitability of Terrestrial Planets

• Venus (0.7 AU radius 0.95 same density as
  Earth)
• Very hot evidence of liquid water in the past
• Mars (1.5 AU radius 0.53)
• Very cold evidence of water today and in the
  past
• Earth (1.0 AU radius 1.0)
• Temperature moderation liquid water today and in
  the past
• Keys
• greenhouse effect (CO2, H2O, oceans)
• size of planet (tectonics, gravity, atmosphere)
• proximity to Sun (luminosity)

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Parable of the Daiseyworld Summary

• Basic principles of Daiseyworld model
• Cybernetic system
• Role of biota in governing temperature when
  luminosity changes (i.e., increases as in Earths
  evolution catastrophic change)
• Appreciate role of models in scientific method
• Hypothesis atmosphere as a signature of life on
  a planet
• Add biota to your list of factors affecting
  habitability

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Continuous Habitability Zone of Our Solar System

• Outer edge of HZ must be less than Mars (1.5 AU)
  orbit (closer to Earth than to Mars)
• Estimate of 1.15 AU
• Inner edge of HZ closer to Earth than Venus
  because Venus lost its greenhouse of H2O early in
  its evolution
• Estimate of 0.95 AU
• Conclusion for planet to maintain liquid H2O
  continuously for 4 BY, HZ is as follows
• gt0.95 AU lt 1.15 AU
• HZ of only 0.2 AU in breadth

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Habitability Zone Elsewhere in the Universe

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Progression of the Sciences Leading to
Astrobiology
Habitability of Extraterrestrial Systems
Astrobiology
Copernican Revolution
Sun-Centered World
Revolutions in Physics, Chemistry, Geochemistry,
and Life Sciences
Earth-Centered World