Transcript Chemical Evolution

Chemical Evolution
From Compounds to Life
Origin of Universe
• The Big Bang
– 15-18 billion years ago- all matter was in one
condensed mass
– Explosion caused matter and energy in universe
– Earth formed 4.6 billion years ago
• Early Earth
– Hot when formed, volcanoes, crust formed and cooled
over hot interior
– Primitive atmosphere: N2, CO2, H2O, H2, CO, NH3,
CH4 (no free O2)
– No ozone layer- energy came from UV rays to make
bigger compounds: amino acids and RNA.
Miller-Urey Experiment
• conducted in 1953 by Stanley Miller with Harold Urey
• the first experiment to about the evolution of prebiotic chemicals and the origin
of life on Earth
– mixture of methane, ammonia, hydrogen, and water vapor
introduced into a 5-liter flask (simulate the Earth's primitive,
reducing atmosphere)
– energized by an electrical discharge apparatus to represent
ultraviolet radiation from the Sun
– products were allowed to condense and collect in a lower flask
which modeled a body of water on the Earth's surface
Miller-Urey Experiment
– heat supplied to this flask recycled the water vapor just as
water evaporates from lakes and seas, before moving into
the atmosphere and condensing again as rain
– after a day of continuous operation
• a thin layer of hydrocarbons on the surface of the water
– after about a week of operation
• a dark brown scum had collected in the lower flask and
was found to contain several types of amino acids,
including glycine and alanine, together with sugars, tars,
and various other unidentified organic chemicals
Heterotroph Hypothesis
1. Primitive atmosphere gases + UV radiation 
2. Early organic compounds 
3. Organic compounds in oceans 
4. Pre-cells formed ---- anaerobic processes for
energy 
5. Photosynthesis cells formed, better able to
survive, produced free O2 as waste
6. Atmosphere formed ozone layer
Oxygen Importance
• Huge electron acceptor
• Highly reactive
• Has an ability to make a lot of ATP which
equals energy
• If it were there evolution would have sped
up so fast there would be no variety
Aristotle (350 BC)
Origin of Life
– decaying material could be transformed by the ‘Spontaneous Action of Nature' into
living animals
Biological Evolution
• First- Coacervates- cell like structures
empty membranes
• RNA-Self replicating molecules and other
compounds were added to membranes
• Together with mineral clays (catalytic
environment) the first self replicating life
system: A Prokaryotic Cell
Evolution of First Life
• Essential functions of Life
– acquisition of energy from the environment
– use of energy to synthesize molecules – metabolism
– information transfer to succeeding generations – genetics
Types of Organisms
• Prokaryotic Kingdom: single-celled
organisms containing no internal structures
surrounded by membranes (therefore there
is no nucleus)
– Monera – bacteria and cyanobacteria
Endosymbiotic Theory
Chloroplast
Aerobic
bacteria
Ancient Prokaryotes
Nuclear
envelope
evolving
Photosynthetic
bacteria
Plants and
plantlike
protists
Mitochondrion
Primitive Photosynthetic
Eukaryote
Ancient Anaerobic
Prokaryote
Primitive Aerobic
Eukaryote
Animals, fungi, and
non-plantlike protists
Endosymbiotic Theory
• Proposed by Lynn Margulis in 1953
• Explained how eukaryotes evolved
• During the time that prokaryotes were
evolving, the ozone layer stopped the Uvs
from making new compounds, a
cannibalistic society probably resulted
• Some prokaryotes became symbiotic
instead of being ingested.
Types of Organisms
• Eukaryotic Kingdoms: all organisms consisting of cells which contain
membrane-bound nuclei
–
–
–
Protista - mostly one-celled organisms – have characteristics of all three other
Eukaryote Kingdoms
Fungi - organisms which decompose stuff
Plantae - organisms which use photosynthesis to make their own food
• Annuals complete life cycle in one season
• Perennials live for more than one season
–
Animalia - organisms which must get organic compounds from food they eat most are able to move
• Invertebrates – no backbone
• Vertebrates – Fish, Amphibians, Reptiles, Birds and Mammals