"Given enough time, the impossible becomes possible, the possible, probable and the probable, virtually certain."

George Wald

CHEMICAL AND CELL EVOLUTION

Web Reading: Essay by Leslie Orgel

I. Introduction

• unifying principle

• two tenets of evolution by natural selection

II. Chemical Evolution

A. Abiotic Synthesis

1. 1920's: Alexander Oparin and John B.S. Haldane

-conditions of early earth

 "The Organic Soup"

2. 1953: Stanley Miller; apparatus

3. Beyond Miller

-undersea vents

-Russell & Hall

4. What are the precursors to biological macromolecules?

B. How were original polymers formed?

1. Dry Puddle Theory

- RNA RNA2 and Molecular Evolution

• Thomas Cech and Ribozymes
• natural selection of RNA
• Summary
  

III. Cellular Evolution

A. Three models to explain Protobionts ("pre-life forms"):

• Coacervate Model (Oparin)
• Proteinoid Microsphere (Fox)
• Lipid Bilayer (Goldacre)
  

1. Coacervate

• What is the basis for the attraction of water to itself and other molecules?
• How do you make coacervates?
• Starch Phosphorylase Experiment of Oparin
  

2. Proteinoids

• How are protenoids made?
• Sydney Fox
• Properties of protenoid microsphere.

3. Lipid Bilayer

• What are the main chemical properties of phospholipids?
• How do phospholipids interact with water?
• What type of coverings do contemporary cells have?

B. PROBLEMS

1. How do you cross the border from protobiont to eubiont (true life form)?

- Requirements for Life Forms

a. boundary membrane

b. metabolism

c. genetic program

d. artificial cells?

2. What are the contemporary vestiges of eubionts?

examples: sulfur bacteria

3. Evolution of Complex Metabolism

• 1945: Norman Horowitz
  

• What are the simplest present day cells?

       -mycoplasma

• Why DNA and not RNA?