History of Life Flashcards
What are the major events of the Paleozoic?
Cambrian explosion First vertebrates, fishes diversify Invasion of land Extensive fern forests First amphibians, reptiles, insects First gymnosperms Permian extinction
What happened during the Cambrian explosion?
Rapid appearance/ diversification of phyla at start of the paleozoic. 565 mya simple multicellular animals appear.
Within 40 my almost all major animal phyla appear.
What are the major events of the Mesozoic?
First dinosaurs, mammals Gymnosperms radiate Dinosaurs radiate First flowering plants Mass extinction at end of Cretaceous
What is the age of Earth?
4.55 billion years
When did life first appear?
3.8 billion years ago
What is the size of the smallest bacterial genomes? Simple ones?
500-900 genes for smallest, 1500-2000 for simple.
What gases were in the atmosphere when life formed?
methane, hydrogen sulfide,
ammonia, carbon monoxide, water vapor
What are theories for the evolution of life?
Extraterrestrial - came from elsewhere in the universe via meteors and asteroids
Chemical (Oparin-Haldane) theory - life originated on earth following a period of “chemical evolution”. inorganic molecules Ô organic molecules Ô biological polymers Ô replicating systems Ô protobionts Ô true cells
Early replicating systems were likely ___ - based.
RNA
Catalytic RNAs called _____ likely preceded
enzymes (proteins).
ribozymes
____ contains genetic information, replicates and can metabolize.
RNA
How many species are currently described?
~300 million
For every human gene, there are ____ microbial genes.
360
How long is the human genome?
~3 billion base pairs
