BIS 2B Lecture Notes - Lecture 26: Paleozoic, Permian, Cellular Respiration

• School: UC-Davis
• Department: Biological Sciences
• Course: BIS 2B
• Professor: Mark Schwartz; Sharon Strauss

Document Summary

Oxygen the first time o2 appeared, it was poisonous to anaerobic prokaryotes, but they evolved ability to metabolize it. Advantages: aerobic metabolism is faster, more energy harvested, so more aerobes than anaerobes in most environs. Also made larger cells and more complex organisms possible. ~1. 5 bya - larger cells required higher o2 levels. Late precambrian (750-~550 mya) - first multi cell aquatic organisms. But are colonies of single celled organisms multicellular? how much specialization is required to be so? from beginning of recorded time to the beginning of life at 550 mya = Precambrian consists of hadean > archean > proterozoic eons, no eras or periods. Paleozoic era (542-270 mya) - soft body marine organisms on thru to age of fishes and colonization of land. 542 mya = 11. 8% of earth"s history. Eras and periods defined by major discontinuities in fossil record. 3 of them in paleozoic era (contains cambrian, ordovician, silurian, devonian,