L3 Origin of life Flashcards
When and how is the earth formed?
Age - 4600 Ma - Earth formed by the gravitational accumulation of dust and larger objects. The mass melts and begins to differentiate into the core, mantle and crust. Water vapour and various gasses are outgassed but do not accumulate due to the great heat and continual bombardment as new material is accumulated. The Moon forms during a major collision.
When did the earth cool enough to solidify its crust to form the first rocks?
3750 Ma
What is panspemia?
What are the approaches to solving the origin of life?
- Analyze living prokaryotes and attempt to reconstruct their common ancestor (essentially the simplest conceivable prokaryote).
- Compare duplicated genes potentially enabling us to reach back beyond that ancestor and estimate some of the earliest components of genetic machinery.
- Reconstruct conditions that existed on Earth in these remote times and simulate these experimentally and see what is produced.
Why are prokaryotes believed to be originated before eukaryotes?
- They appear earlier in fossil record.
- They are simpler in virtually every aspect.
- There is evidence that eukaryotes evolved from prokaryotes.
What are the fundamental similarities between prokaryotes and eukaryotes?
- Reconstruct conditions that existed on Earth in these remote times and simulate these experimentally and see what is produced.
- In living organisms all amino acids are laevo-rotatory and in nucleic acids all the sugars are dextro-rotatory.
What does LUCA mean?
Last Universal Common Ancestor.
What are the chemicals produced by simulating conditions on the primitive earth?
- Amino acids - includimg all of the biologically important ones.
- Purines and pyrimidines - Including the four bases of RNA (adenine, cytosine, guanine and uracil) but not thymine which replaces uracil in DNA).
- Sugars
- Porphyrins - molecules whihc are forerunners for vitamin B12, chlorophylls.
- Complex tar like substance which defies analysis.
What basic machinery does all living organisms use?
information is stored in DNA and transcribed and translated into protein using RNA.
