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 Ureyconducted in 1953 by Stanley Miller with Harold Urey• the first experiment to about the evolution of prebiotic the first experiment to about the evolution of prebiotic

chemicals and the origin of life on Earthchemicals and the origin of life on Earth– mixture of methane, ammonia, hydrogen, and mixture of methane, ammonia, hydrogen, and

water vapor introduced into a 5-liter flask water vapor introduced into a 5-liter flask (simulate the Earth's primitive, reducing (simulate the Earth's primitive, reducing atmosphere) atmosphere)

– energized by an electrical discharge apparatus to energized by an electrical discharge apparatus to represent ultraviolet radiation from the Sunrepresent ultraviolet radiation from the Sun

– products were allowed to condense and collect in products were allowed to condense and collect in a lower flask which modeled a body of water on a lower flask which modeled a body of water on the Earth's surfacethe Earth's surface

Miller-Urey Experiment– heat supplied to this flask recycled the water heat supplied to this flask recycled the water

vapor just as water evaporates from lakes and vapor just as water evaporates from lakes and seas, before moving into the atmosphere and seas, before moving into the atmosphere and condensing again as raincondensing again as rain

– after a day of continuous operation after a day of continuous operation • a thin layer of hydrocarbons on the surface a thin layer of hydrocarbons on the surface

of the waterof the water

– after about a week of operationafter about a week of operation• a dark brown scum had collected in the a dark brown scum had collected in the

lower flask and was found to contain several lower flask and was found to contain several types of amino acids, including glycine and types of amino acids, including glycine and alanine, together with sugars, tars, and alanine, together with sugars, tars, and various other unidentified organic chemicals 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

Origin of LifeAristotle (350 BC)Aristotle (350 BC)

– decayingdecaying material could be transformed by the ‘Spontaneous Action of Nature' into material could be transformed by the ‘Spontaneous Action of Nature' into living animalsliving 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 LifeEssential functions of Life

– acquisition of energy from the environment acquisition of energy from the environment

– use of energy to synthesize molecules – use of energy to synthesize molecules – metabolismmetabolism

– information transfer to succeeding generations – information transfer to succeeding generations – geneticsgenetics

Types of Organisms

• Prokaryotic Kingdom: Prokaryotic Kingdom: single-celled single-celled organisms containing no internal structures organisms containing no internal structures surrounded by membranes (therefore there surrounded by membranes (therefore there is no nucleus) is no nucleus) – MoneraMonera – bacteria and cyanobacteria – bacteria and cyanobacteria

Aerobic bacteria

Ancient Prokaryotes

Ancient Anaerobic Prokaryote

Primitive Aerobic Eukaryote

Primitive Photosynthetic Eukaryote

Chloroplast

Photosynthetic bacteriaNuclear

envelope evolving Mitochondrion

Plants and plantlike protists

Animals, fungi, and non-plantlike protists

Endosymbiotic Theory

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: Eukaryotic Kingdoms: all organisms consisting of cells which contain all organisms consisting of cells which contain

membrane-bound nucleimembrane-bound nuclei– ProtistaProtista - mostly - mostly one-celled organisms – have characteristics of all three other one-celled organisms – have characteristics of all three other

Eukaryote KingdomsEukaryote Kingdoms

– Fungi - Fungi - organisms which decompose stufforganisms which decompose stuff

– Plantae - Plantae - organisms which use photosynthesis to make their own food organisms which use photosynthesis to make their own food • AnnualsAnnuals complete complete life cycle in one seasonlife cycle in one season

• Perennials Perennials live for more than one seasonlive for more than one season

– Animalia - Animalia - organisms which must get organic compounds from food they eat - organisms which must get organic compounds from food they eat - most are able to movemost are able to move

• Invertebrates – Invertebrates – no backboneno backbone

• Vertebrates – Vertebrates – Fish, Amphibians, Reptiles, Birds and MammalsFish, Amphibians, Reptiles, Birds and Mammals