RNA world • Can satisfy most requirements for definition of life • RNA can store information • Duplicate self or other molecules • Can catalyze reactions like enzymes • form peptide bonds • The RNA world evolved into the DNA protein world of today with DNA taking over the function of data storage and proteins with flexible amino acid composition became specialized catalytic molecules.
RNA world hypothesis • Lipid vesicles in montmorillonite clay. This clay is a product of the erosion of volcanic ash. Absorbs water and facilitates lipids to form vesicles. • Under the right conditions it will also cause nucleotides to assemble into RNA polymers. • The formation of RNA and lipid vesicles may result in self- replicating RNA in lipid membranes.
What can happened? Chicken or egg? Genetic instructions or energy- generating reactions? Changing abiotic factors Sequence of events?
Evolved into many shapes and sizes Azotobacter Staphylococcus aureus
Borrelia burgdorferi (cause of Lyme’s disease) Treponema pallidum (cause of Syphilis) and Borrelia burgdorferi (cause of Lyme disease)
With a few million years Microbe-microbe interactions Niche filling
This basalt outcrop on the Santa Rosa Plateau of southern California is covered by a dense crust of four colorful lichen species. I n the Anza-Borrego Desert of southern California, the sun-baked boulders are devoid of lichens. Instead, the rocks are coated with " desert varnish ," a reddish layer of clay and iron oxide precipitated by remarkable bacteria. This large boulder has split apart revealing the lighter granodiorite beneath. Lichens Algal cells + fungi
Extreme environments “ Archaea ” 45-67°C and pH as low as 0.5 Thermoplasma acidophilum
Classifying microbes is difficult • Morphology--see differences?
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