Abiotic  Biotic Transition

1. Abiotic  Biotic Transition on Hadean-Archean Earth Outcrop of metamorphosed volcano-sedimentary rocks from Porpoise Cove, Canada.

2. Living cells are made of molecules! • Modern cells fall into 3 categories (Domains): • Archaea • Bacteria • Eukarya No matter which Domain a cell belongs to, it consists of 4 types of biomolecules: • Carbohydrates • Lipids • Proteins • Nucleic acids

3. 1) Small organic molecules were formed from even simpler inorganic molecules in the environment. • During the late Hadean Era (4.0 – 3.5 bya), Earth was very different than today! • Atmosphere mostly CO2, CH4, NH3, N2, H2O • Intense energy present – lightning, geothermal, UV radiation

4. 1) Small organic molecules were formed from even simpler inorganic molecules in the environment. • The Miller – Urey experiment, in 1953, first showed that small organic monomers could be formed by adding energy to simple inorganic molecules, and mixing amino acid them in water! nucleotide mid- to late-Hadean Era = about 400,000,000 years!

5. 2) Then the monomers bonded together to form polymers • Organic monomers can form chains, called polymers • Dehydration reaction:

6. 2) Then the monomers bonded together to form polymers • Clay is a sediment with a regular, repeating layered mineral pattern • Has many industrial uses in absorbing & combining chemicals • Over time, volcanic ash often becomes clay in moist environments

7. 2) Then the monomers bonded together to form polymers • What about hydrothermal vents as the setting for the origin of life? • Some researchers hypothesize that a reaction between S compounds could have provided the energy needed to produce organic carbon monomers. • One product of this reaction is pyrite (also known as fool's gold). • Organic monomers may also self-organize upon the surface of pyrite.

8. 3) Next, the RNA polymers became able to copy themselves, and to be inheritedRNA3) RNA polymers became able to copy themselves, and to be inherited • RNA likely preceded DNA • Nucleic acids hold chemical instructions for building proteins in cells • Any time a new cell is formed, the nucleic acid must be copied first!

9. 3) RNA polymers became able to copy themselves, and to be inherited • Proteins are vital molecules in modern cells • Enzymes control chemical reactions, including DNA-RNA • Experiments have shown RNA can replicate without help from enzymes – “ribozymes” • “RNA World” hypothesis

10. 3) RNA polymers became able to copy themselves, and to be inherited • All modern cells must be descended from other cells • First step is making a new copy of the “directions” • Each new cell is an (almost) exact copy of its parent cell • Successful cells are more likely to pass on the traits that make them successful!

11. 4) Biomolecules became packaged into membranes made of lipids, which separated them from their watery environment. • All lipids share the characteristic of being hydrophobic. • Phospholipids have both a H-phobic and H-philic region! • Naturally and automatically assume a spherical shape when surrounded by water.

12. 4) Lipid membranes allow a cell to maintain homeostasis. • All cells must be able to maintain a constant internal environment – even as their external environment changes! • Stable internal environment allows complex chemistry to take place  LIFE !!!!!!

13. Once homeostasis was in place, and genetic inheritance had begun, biological evolution by natural selection began, and has continued for about 3,500,000,000 years..........did you think it was done, just because today’s organisms are here?