What is the cenanscestor and/or LUCA refer to and how is that different from the primordial form? 

Last universal common ancestor is the last common ancestor of all extant organisms. Primordial form is the first living thing.

 What was significant about the first enzymes?

They were likely made of RNA and could break and reform chemical bonds that link nucleic acids together in chains.

  Explain the rationale that DNA/protein based life may not have come first. 

DNA alone could not function without proteins. Proteins alone cannot propagate themselves. Not sure which would have come first.

   Explain why RNA is probably a better candidate for the first forms of life.

It has both a genotype and a phenotype, can function as an enzyme and information storage. 

    Define what life is. 

Possession of a genotype and a phenotype (ability to store and transmit information and ability to express that information), ability for replication, and evolution

   Why is DNA a better information repository than RNA? 

a.    Because its double-stranded and thus more stable and less error prone. 

   Explain why RNA is thought to be more ancient.

The ribosome is made of RNA and uses RNA during translation. The basic currency for biological energy is ribonucleoside triphosphates, such as ATP and GTP are similar to ribonucleotides

    Describe the experiment by Saul Spieglmen and colleagues on RNA evolution. How did this demonstrate that RNA is a life form?

Used RNA from a virus called bacteriophage Qb to demonstrate that populations of RNA can evolve in test tubes. When a small amount of Qb RNA is incubated with Qb replicase for a few minutes, the replicase makes copies of RNA and copies of the copies.

   What is the holy grail for origins of life research dealing with the RNA world? What is the evidence for it?

Demonstration that RNA can self replicate without help from proteins

 List the four issues that need to be addressed for building the primordial form of life. 

1)   Information-containing biomolecules need to be made from simple inorganic compounds. Where did these compounds come from?

2)   The chemical reactions that construct larger molecules from simple inorganics must be favorable and have a source of energy. What were these reactions?

3)   The building blocks must be able to self-assemble into polymers such as RNA and polypeptides. How did this happen?

4)   Larger biomolecules must be protected from harsh environmental conditions. How was this accomplished?

   Describe the unique characteristics of the Murchison meteorite and the isomeric state of these molecules. Explain what this might mean for the possibility of the panspermia hypothesis. 

It had high concentrations of amino acids. There were both D- and L-stereoisomers. (biological amino acids are almost purely the L-form). Terrestrial life could not be the source of the compounds the researchers found. This possibly supports panspermia hypothesis: that life originated elsewhere and traveled to earth, but not likely that microorganisms would survive the descent to earth.

Explain some of the doubts about the Miller experiments and what this implies about the early atmosphere of earth. 

Did liquid water exist at the time of life’s origin? Were the atmospheric conditions as predicted?

What is the Oparin-Haldane Model? 

a.    All of the necessary conditions for life to evolve are here on earth. 

What are the major problems with the building blocks that are using for a self-replicating system?

? 

    What is the hydrolysis problem for early life? What are some potential solutions?

Organic molecules were spread across the ocean and not in high concentrations. One solution is possibly tide pool areas. Another is ionized clay molecules acting as catalysts.

   What’s the final challenge in any Oparin-Haldane model for how life began on earth?

? Self replication or whether early earth would have been hospitable enough to allow life to evolve

  What does the sedimentary rock record tell us about the origin of life on earth? What conditions immediately preceded the earliest sedimentary rocks?

Life was established on Earth by 3.7 billion years ago. The rocks were exposed to high temps and pressures which compacted the rocks and crystallized many of the minerals. Erosion, plate tectonics, and volcanic eruptions have destroyed many rocks.

  How did RNA acquire cells?

Selection for compartmentalization, concentration of chemicals, allows for genotypes and phenotypes to be linked.

Polyamino acids in water spontaneously form microspheres. Possibly inorganic mineral deposits forming tiny compartments.

  How useful is the fossil record for early cellular life research? 

Not very useful. Fossil record for times earlier than 2.5 billion years ago is too spotty to allow paleontologists to trace lines of evolutionary descent from present-day organisms back to over 3 billion years ago. We have no direct way of knowing whether the organisms recorded in these rocks represent extinct or living branches of the tree of life. 

   Why are some researchers skeptical about our ability to construct deep evolutionary history using phylogenetic analysis?

Prokaryotes lack sufficient structural diversity to allow the reconstruction of morphology-based evolutionary trees. It is difficult using sequence data for phylogenies because it is hard to identify a genes that shows recognizable sequence similiarities between distantly related species.

  When is it thought that the earliest eukaryote lived? How was this determined?

1.85-2.1 billion years ago. A fossil of a spiral shaped organism found in the Empire Mine in Michigan.

    What is Woese’s hypothesis for the evolution of early life?

The discordance among the whole-life phylogenies can be explained by lateral gene transfer.

What’s the difference between the Ring of Life hypothesis and the chronocyte hypothesis? 

Ring of Life - The first eukaryote arose when a bacterium fused with an archean. The lineage retained informational genes from the archaean and the metabolic genes from the bacterium.

Chronocyte – The deepest fork in the tree of life separates a lineage that will become the Eucarya (chronocytes). The chronocyte lineage evolved a cytoskeleton and the ability to eat other microbes by phagocytosis. A chronocyte ate an archaean and became a endosymbiont. This evolved into the nucleus.

 How are viruses connected to the Tree of Life? Are they likely to be the earliest forms of life, or offshoots from it?

Maybe rogue genes that found ways to self replicate, so probably an offshoot.