Chapter 20 Lecture Enrichment Ideas
Discuss the differences between reduction and oxidation as chemical processes. Examine why the reducing atmosphere would support development of larger organic molecules, while an oxidizing atmosphere would break down large molecules.
Discuss the presence of organic subunits such as amino acids (including some not produced by organisms) in meteorites suggesting that these molecules probably arose in space (or at least somewhere other than earth). How would this information affect your ideas about chemical evolution? Could some of these molecules have been brought to earth this way?
Examine the relatively new ideas concerning reverse transcriptase and ribozymes, as opposed to the central dogma of molecular genetics as proposed by Crick. Why did it take so long to find these exceptions to the central dogma, and what effect does their presence have on our understanding of how life might have arisen and developed on earth?
Discuss why it would be likely that a membrane would be necessary before a cell would develop.
Describe the evolutionary significance of continental drift in the development of monotremes, marsupials, and placental mammals. Discuss the fact that South America was inhabited by marsupials until relatively recently (within the last 20,000 years or so), when the land bridge formed between North and South America, which allowed placental mammals to reach South America and led to the extinction of many marsupials. Consider whether the same thing is happening in Australia now, since humans have introduced dogs, rats, rabbits, etc.
Discuss the different mechanisms that might be at work in the gradualist model for speciation versus the punctuated equilibrium model and whether evolution might actually work in both ways.
The early discussion of "What is Life" from Chapter 1 can be reviewed here with hindsight on the complexity of metabolism.
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