MICRB265 Lecture Notes - Lecture 3: Cambrian Explosion, Lithotroph, Phototroph
1 May 2019
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Lecture 3: the rna world: life began in an rna world: Nucleic acid is needed to make proteins and proteins are needed to make nucleic acid. Widely believed that rna molecules acted as catalysed for biological reactions because they can fold like proteins. Rna was both the information molecule and the catalyst. In the precellular life, rna"s function as catalyst was replaced by proteins, which were more efficient catalysts. Rna"s function was replaced by dna, which is a more stable molecule: luca. High levels of horizontal gene transfer: earliest form of metabolism anaerobic. Obtain energy from oxidation of h2 chemolithotroph. Chemo lithotrophic metabolism made a lot of organic compounds that allowed the evolution of chemo lithotrophic organisms: cambrian explosion: life diversification associated with o2. Cyanobacteria figured out how to split water to release energy. After increase in o2 levels, iron precipitated in the oceans. O2 was toxic so organisms had to adapt to the presence of o2 in the air.
