Origin of Life

How would you define life? Monday, March 9

Tuesday, March 10th It is known that the continents once existed as one land mass known as Pangea. What is an explanation for the separation of this land mass into the continents we have today?

Wednesday, March 11th What kind of evidence would you use to confirm humans relationships to mammals?

John Kyrk Evolution Timeline http://www.johnkyrk.com/evolution.html As we scroll through the timeline write down interesting facts, questions, etc from each that we go through Example: Hadean Era - Sun Ignites, Solar System Forms

The evolutionary tree of life can be documented with evidence. Bacteria Archae- bacteria Animalia Fungi Protista Plantae 4500 4000 3500 3000 2500 2000 500 1500 1000 Formation of earth Molten-hot surface of earth becomes cooler Oldest definite fossils of prokaryotes Appearance of oxygen in atmosphere of eukaryotes First multicellular organisms Appearance of animals and land plants Colonization of land by animals Paleozoic Mesozoic Cenozoic Millions of years ago ARCHEAN PRECAMBRIAN PROTEROZOIC The evolutionary tree of life can be documented with evidence. The Origin of Life on Earth is another story…

What is Life? First we have to define LIFE… Organized as cells Respond to stimuli Regulate internal processes Homeostasis Use energy to grow Metabolism Develop Change & mature within lifetime Reproduce Heredity DNA / RNA Adaptation & Evolution

The Origin of Life is Hypothesis Special Creation Was life created by a supernatural or divine force? not testable Extra-terrestrial Origin Was the original source of organic (carbon) materials comets & meteorites striking early Earth? testable Spontaneous Abiotic Origin Did life evolve spontaneously from inorganic molecules?

Conditions on Early Earth Reducing atmosphere water vapor (H2O), CO2, N2, NO2, H2, NH3, CH4, H2S lots of available H & its electron no free oxygen Energy source lightning, UV radiation, volcanic low O2 = organic molecules do not breakdown as quickly What’s missing from that atmosphere?

Origin of Organic Molecules Water vapor Condensed liquid with complex, organic molecules Condenser Mixture of gases ("primitive atmosphere") Heated water ("ocean") Electrodes discharge sparks (lightning simulation) Water Abiotic synthesis 1920 Oparin & Haldane propose reducing atmosphere hypothesis 1953 Miller & Urey test hypothesis formed organic compounds amino acids adenine

Stanley Miller Produced: amino acids hydrocarbons nitrogen bases other organics

Key Events in the Origin of Life Origin of Cells (Protobionts or “Protocells”) lipid bubbles → separate inside from outside → metabolism & reproduction Origin of Genetics RNA is likely first genetic material multiple functions: encodes information (self- replicating), enzyme, regulatory molecule, transport molecule (tRNA, mRNA) makes inheritance possible makes natural selection & evolution possible Origin of Eukaryotes endosymbiosis

Protocells A liposome is “giving birth” to a smaller liposome Some liposomes could carry out metabolic reactions and export products (ie. phosphate and maltose) if the enzymes were carried through in the creation of new liposomes

Origin of Genetics RNA is likely first genetic material multi-functional codes information self-replicating molecule makes inheritance possible natural selection & evolution enzyme functions ribozymes replication regulatory molecule transport molecule tRNA & mRNA

Timeline Key events in evolutionary history of life on Earth 3.5–4.0 bya: life originated 2.7 bya: free O2 = photosynthetic bacteria 2 bya: first eukaryotes

Prokaryotes O2 in the Atmosphere Dominated life on Earth from 3.5–2.0 bya O2 in the Atmosphere Oxygen begins to accumulate 2.7 bya reducing —> oxidizing atmosphere evidence is banded iron in rocks = rusting makes aerobic respiration possible photosynthetic algae

First Eukaryotes ~2 bya Development of internal membranes Prokaryotic create internal micro-environments advantage: specialization = increase efficiency NATURAL SELECTION! nuclear envelope endoplasmic reticulum (ER) nucleus infolding of the plasma membrane plasma membrane DNA cell wall plasma membrane Prokaryotic ancestor of eukaryotic cells Prokaryotic cell Eukaryotic cell

1st Endosymbiosis Evolution of eukaryotes origin of mitochondria engulfed aerobic bacteria, but did not digest them mutually beneficial relationship natural selection! internal membrane system aerobic bacterium mitochondrion Endosymbiosis Ancestral eukaryotic cell Eukaryotic cell with mitochondrion

2nd Endosymbiosis Evolution of eukaryotes origin of chloroplasts Eukaryotic cell with mitochondrion Evolution of eukaryotes origin of chloroplasts engulfed photosynthetic bacteria, but did not digest them mutually beneficial relationship natural selection! photosynthetic bacterium photosynthetic bacterium chloroplast Endosymbiosis mitochondrion Eukaryotic cell with chloroplast & mitochondrion

Theory of Endosymbiosis Evidence structural mitochondria & chloroplasts resemble bacterial structure genetic mitochondria & chloroplasts have their own circular DNA, like bacteria functional mitochondria & chloroplasts move freely within the cell mitochondria & chloroplasts reproduce independently from the cell

Cambrian Explosion Diversification of Animals within 10–20 million years most of the major phyla of animals appear in fossil record 543 mya

Precambrian Era Longest of the eras Comprises about 87% of the geological timescale Mass Extinctions Episode of large-scale extinction in which large #’s of species disappear in a few million years of less At least 5 major mass extinctions throughout history: Ordovician, Devonian, Permian, Triassic, and Cretaceous

Factors that Influence Evolution Continental Drift: Movement of continents with respect to one another over the earths surface Why do the continents drift? Plate Tectonics! Plate Tectonics: Concept that the earths crust is divided into a # of fairly rigid plates

Where have we been? Models of the origin of life HWE and population genetics Macroevolution/Speciation What has driven the diversity and unity of life? What is the end result of changes in populations (microevolution) over time? How do times of ecological stress affect species diversity and the rate of speciation?

The process of evolution drives the diversity and Big idea #1 The process of evolution drives the diversity and unity of life.

Multiple Choice Answers 9. B 10. B 20. C 58. B