BSC 2010 Lecture Notes - Lecture 1: Multicellular Organism, Positive Feedback, Chlorella
30 May 2016
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Document Summary
Formation of nucleic acids that could reproduce themselves and contain the information to produce proteins. Biological molecules were enclosed in a membrane, to form a cell. Fatty acids, which form membrane-like films in water, were important in forming membranes. Membranes separate the cell from the surrounding environment. For 2 billion years, organisms were unicellular prokaryotes. Early prokaryotes were confined to oceans, where they were protected from uv light. There was little or no o2 in the atmosphere, and hence no protective ozone (o3) layer. The energy of sunlight is transformed into the chemical-bond energy of biological molecules. Earliest photosynthetic cells were probably similar to cyanobacteria. O2 was a by-product of photosynthesis, and it began to accumulate in the atmosphere. Organisms that could tolerate o2 evolved aerobic metabolism (energy production using o2), which is more efficient than anaerobic metabolism. Organisms were able to grow larger; aerobic metabolism is used by most living organisms today.
