Post on 11-Jan-2016
Early Earth and the Origin of LifeLogical Progressio
nPossible Scenarios Supporting Data Problems
Abiotic Synthesis of Monomers
Reducing Atmosphere
Deep Sea Outer Space Miller-Urey Experiment
Imbedded organic compounds found in vents
Organics found in meteors and comets
Abiotic Synthesis of Polymers
Concentrated hot monomers form polymers as evaporation and cooling takes place
Process fits all scenarios above but differs in location
Minerals, clay, “pyrite” , iron & nickel sulfides could be used as catalysts
Monomers form polymers when dripped on hot sand, rock, or clay
Polymers have been found embedded in deep sea vents
Origin of Genetic Information“It’s an RNA
world”
RNA was the first genetic molecule(genotype) that functioned also as an enzyme (phenotype)
Natural selection picked the best RNA molecules as it replicated and “metabolized” available monomers
RNA-amino acid interaction by molecular cooperation
Short sequences of RNA can replicate with zinc as catalyst
RNA can act enzyme like (ribozyme)
RNA types allow natural selection
Formation of Protobiontsmembrane bound “cells” with some properties of life
Abioticly produced molecules interact to maintain a constant internal environment showing irritability and metabolism
Protobionts called Liposomes form from lipid, COH, and protein that have:1. Lipid bilayer that shows osmosis
2. Voltage across membrane (membrane potential)3. Engulf and split
4. Simple metabolism
A.A. Protein
Sugar Starch
NucleotidesDNA
C+H+N+O
Amino acids simple sugars lipids
H20,H, CH4, NH3 + Energy amino acids. Nucleotides sugars
Vents used iron and sulfur and hot water to build from CO2 and ammonia
Comets, meteors, space dust showered earth with organic molecules
3.5 bya fossilized stromatolites (layered clay rock) formed by 1st prokaryotes
Timeline of Key Life Events on Earth
4.6 bya 4 3.5 3 2.5 2 1.5 1 0.5 Present
Earth forms
Prokaryotes appear
Prokaryotes photosynthesize; O2 revolution by cyanobacteria, kills most prokaryotes, leads to cell respiration
Eukaryotes appear!!!Endosymbiont theory – mitochondria and plastids are former small prokaryotes that lived in larger cells Evidence:
Multicellular organisms appear(algae & soft-bodied animals in water)
Cambrian Explosion!Most phyla form
Colonization of land~adaptations to combat desiccation & gravity
1. Inner membrane is like those of prokaryotes 2. They replicate like prokaryotes 3. Have cell machinery (i.e. ribosomes) like prokaryotes 4. Similar size, have circular DNA, & RNA sequences like pros
Amino Acids and other organic compounds found in sample
Miller and Urey Experiment 1953 (testing Oparin and Haldane’s idea)
Reducing Atmosphere
Energy source (Lightning)
Slide 1
Slide 1
A Model for Gene Replication
RNA WAS THE ORIGINAL GENETIC MATERIAL
Slide 1
“Life-Like” Activities of a Liposome
Simple Reproduction Simple Metabolism
Slide 1
Cooperation of RNA and Proteins
Slide 1
Primitive Earth: Reducing Atmosphere?
26-14-DeepSeaVent-B.movSlide 1
Clock Analogy for Key Events in Earth’s History
Slide 2
Rise of Earth’s Atmospheric Oxygen
Slide 2
Slide 2
Slide 2