Transcript How Did Life Begin?

How Did Life Begin?
I thought we were done with all this
chemistry stuff…….
Molecular Building Blocks
• Cells are composed of 4 types of
macromolecules
– I don’t have to tell you what they are
• Today on earth these do not self-assemble
from simpler molecules
– Oxygen
– Some life form would consume/modify them
But on earth a long long time ago
• Conditions were different than now
• Atmosphere was hydrogen cyanide, CO2,
CO, nitrogen, hydrogen sulfide, water vapor
• If that was then and now is now….can you
make organic molecules out of this stuff?
• Stanley Miller and Harold Urey
Experimental results are in
• Miller and Urey’s device produced
– Amino acids
– Sugars
– Nitrogenous bases
But it’s a long way from here to
there…..
• Large organic molecules can organize themselves
– Proteinoid microspheres form when polypeptide chains
cool
– These are hollow and surrounded by lipid
• RNA is really important
–
–
–
–
Probably was the first information molecule
RNA can duplicate itself
Rna can function as an enzyme (ribozyme)
DNA likely evolved from RNA
Origin of the Eukaryotes
• Oxygen accumulates
• Endosymbiotic theory
– Mitochondria
– Chloroplasts
• Sex and multicellularity
– Diversity…….diversity…….diversity
Fossils
• Know the process on page 539, fossil
formation
• Dating
– Relative dating and index fossils
– Radiometric dating
• Half life concept
– The geologic time scale
– Plate tectonics
Clade Dinosauria has survived
• Macroevolution
– Adaptation and extinction (look at graph on page 548)
– Adaptive radiation and convergent evolution
• Rate of evolution
– Slow (= gradualism)
– Fast in spurts (= punctuated equlibrium)
• Coevolution matters to us
– Insects and flowers