THE SEARCH FOR DESIGN:

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1 THE SEARCH FR DESIGN: A Normal Part of Science! NASA Space Flights / SETI Airplane Crash Investigation Arson Investigation Investigation of Suspicious Deaths Archaeology Studying the rigin of Life verhead #1

2 PREDICTINS ABUT THE RIGIN F LIFE Initial Disorganization: 1. Natural processes should be sufficient to produce life (no supernatural intervention). 2. We should find evidence that the early earth s environment was much different than it is today. Initial Complexity: 1. Life should be far too complex to be the result of purely natural processes. 2. We should find evidence that the early earth s environment was suitable to sustain life as we know it probably quite similar to the way it is today. Studying the rigin of Life verhead #2

3 WHAT IS LIFE? Imagine two chemically identical collections of matter side by side. The first takes in nutrients, excretes wastes, responds to its environment, grows, and reproduces. It is alive. The second does none of these things. It is a corpse. Nobody knows what makes one alive and the other dead. Science can describe how life operates but cannot tell us what it is nor why it exists. Studying the rigin of Life verhead #3

4 LIFE IN THE LAB? Basic design of Dr. Stanley Miller s apparatus. ther experiments use different energy sources or extra gases, but all are based on Miller s design. Studying the rigin of Life verhead #4

5 Glycine (gly) LLeucine (leu) H CH2 CH Copyright 2003 by David A. Prentice The 20 Amino Acids Used in Proteins: LAlanine (ala) H CH 3 LIsoleucine (ileu) H CH CH 3 CH 3 LSerine (ser) H LThreonine (thr) H C H CH2 H LCysteine (cys) SH LValine (val) H CH H 3 C CH 3 LProline (pro) LAspartic acid (asp) H CH2 C H 3 C CH 3 LAsparagine (asn) LGlutamic Acid (glu) LPhenylalanine (phe) H N + C C H N + C C LTyrosine (tyr) LMethionine (met) C NH 2 C H S CH 3 LLysine (lys) LGlutamine (gln) LArginine (arg) LHistidine (his) LTryptophan (try) H 3 N + C N CH C NH 2 N HC N 3 N + C NH Source: James Watson, Molecular Biology of the Gene Studying the rigin of Life verhead #5 C CH NH

6 Problems With The Primordial Soup 1. Nonxygen Atmosphere. Even the lowest Precambrian sediments, all the way down to basement rock, contain red beds oxidized deposits showing the presence of free oxygen. The evidence indicates that the atmosphere has always contained free oxygen. No traces of the primordial soup have ever been found. Studying the rigin of Life verhead #6

7 Problems With The Primordial Soup 2. xygenuv Dilemma. Without oxygen in the atmosphere, there would be nothing to filter out deadly longwave (3000Å or longer) ultraviolet. Skin damage due to UV light Wavelength in Angstrom units a. Free oxygen = wrong reactions. b. No free oxygen = Rapid breakdown of the methane and ammonia in the primordial soup; Destruction of amino acids and other organic compounds as fast as they could form. Studying the rigin of Life verhead #7

8 Problems With The Primordial Soup 3. Trapping Mechanism. The same energy source that produces the organic compounds quickly destroys them unless they are removed by a cold trap. No such trapping mechanism is known in nature. Studying the rigin of Life verhead #8

9 Problems With The Primordial Soup 4. ptical Isomers. 19 of the 20 amino acids used in proteins can exist in mirror images known as the lefthanded (L) or righthanded (D) form. For example: Random chemical processes produce a 50/50 mix. Yet protein in living cells is made up of NLY the L forms. This CANNT be explained by chemical processes alone. Studying the rigin of Life verhead #9

10 Amino Acids and Probability Suppose a cell used 1 type of amino acid instead of 20. Could random chemical action accidentally put together just 125 proteins of 100 amino acids each, using only lefthanded amino acids? It s about as likely as a groundhog with a 50/50 chance of making it across any one lane getting across 12,500 lanes on a superhighway. Studying the rigin of Life verhead #10

11 a. We have to start with the right chemicals to make amino acids, bases, and sugars. b. Hundreds or thousands of these must work their way past the Problems With The Primordial Soup 5. Chemistry. At least some of these must be able to attract the other molecules they need. d. Now they must form a cell membrane and absorb exactly the useless compounds in their way to link into each molecule of protein and RNA/DNA. c. Next, these have to come together into clusters such as coacervates. crosssection of a typical animal cell after The Concise Columbia Encyclopedia (CD version) A cell is more than just a few amino acids strung together! necessary molecules to put together a mechanism to reproduce. e. Finally, the whole thing has to undergo some unknown process to come alive. Studying the rigin of Life verhead #11

12 Is It Soup Yet? N! Even with a primordial soup containing only Carbon, Hydrogen, Nitrogen, and xygen, the chemistry is so complicated that experimenters buy purified amino acids instead of making their own. But this soup is far too simple! (1) Two amino acids require Sulfur; (2) DNA and RNA require Phosphorous; (3) Early plants required Magnesium for photosynthesis; and (4) Living things also need Iron, Copper, Calcium, and many other elements. When these are added to the soup, the chemistry to produce a cell becomes impossibly hard. Studying the rigin of Life verhead #12

13 Probability of Forming a Cell The simplest possible cell would have about 124 proteins of 400 amino acids each. If the primordial soup contained nothing but pure amino acids, the probability that the right ones could come together to form a cell is less than 1 in 10 78,400. If there were as many possible types of cells as atoms in the universe (about ), the probability is still less than 1 in 10 78,300. Ideal conditions everywhere in the universe for trillions of years wouldn t help. Nothing could reproduce because there would be no DNA. Studying the rigin of Life verhead #13

14 Problems With The Primordial Soup 6. DNA/Enzyme Dilemma Special proteins called enzymes are crucial to the operation of cells, making some reactions proceed billions of times faster. Without them life would be impossible. DNA is needed to make enzymes, but enzymes are needed to make DNA! Since both have to be present at the same time, they could not have evolved by gradual changes in dissimilar mechanisms. Where did they come from? Studying the rigin of Life verhead #14

15 Problems With The Primordial Soup 7. The Cell Membrane. Phospholipids can combine spontaneously to form membranes. However, these membranes are impermeable to many substances needed for cell growth and reproduction. Membranes in living things contain microscopic gateways called ion channels or permeases, which let needed substances in and out. They are present only because DNA contains the instructions to make them. Detail of double phospholipid membrane showing 2 ion channels Cutaway view of animal cell surrounded by membrane Ion channels are needed to form DNA, but DNA is needed to form ion channels. Studying the rigin of Life verhead #15

16 Problems With The Primordial Soup 1. Nonxygen Atmosphere required. 2. xygenultraviolet Dilemma. 3. Need for a sophisticated Trapping Mechanism. 4. ptical Isomers. 5. Chemistry. 6. DNA/Enzyme Dilemma. 7. Impermeability of Cell Membrane. Studying the rigin of Life verhead #16

17 Is There Life on ther Planets? We don t even know for sure that there are planets outside the solar system. Reports of planets around other stars are based on periodic fluctuation in the wavelength of light from those stars, interpreted to mean that an orbiting companion is pulling the star alternately toward and away from us. However, the companion need not be a planet; it could be a brown dwarf star. Even if the objects really are planets, they would have to be very large and very close to their stars to produce enough fluctuation to be seen from earth. They would have far too much gravity and heat to support life. N A S A P h o t o Studying the rigin of Life verhead #17