Transcript You Light Up My Life

First Atmosphere
• Hydrogen gas
• Nitrogen
• Carbon monoxide
• Carbon dioxide
• No gaseous oxygen
Origin of Organic Compounds
• Stanley Miller Experiment – next slide
• Amino acids, other organic compounds can
form spontaneously under conditions like
those on early Earth
electrodes
to
vacuum
pump
CH4
NH3
H2O
H2
spark
discharge
gases
water out
condenser
water in
water droplets
water containing
organic compounds
boiling water
liquid water in trap
Metabolism
• The organic molecules interacted causing
chemical reactions, leading to metabolism
RNA World
• RNA may have been first genetic material
• RNA can assemble spontaneously
– Self replicating – can copy itself
• How switch from RNA to DNA might have
occurred is not known
Proto-Cells
• Microscopic spheres of proteins or lipids can
self assemble
• Tiny sacs like cell membranes can form under
laboratory conditions that simulate conditions
in evaporating tidepools
• Sidney Fox – proteins chains, protenoids
(spheres that were selectively permeable )
• David Deamer – lipids, self-assembled into
small, water-filled sacs resembling cell
membranes.
The First Cells
• Originated in Archeon Eon
• Were prokaryotic heterotrophs
• Secured energy through anaerobic
pathways
– No oxygen present
– Relied on glycolysis and fermentation
Order of Origination
• Anaerobic heterotrophic prokaryotes
• Origin of photosynthetic Eubacteria
– cyclic pathway first
– noncyclic pathway next
– Oxygen accumulates in atmosphere
• Origin of aerobic respiration
Advantages of Organelles
• Infolding of membrane led to some organelles
• Nuclear envelope may have helped to protect
genes from competition with foreign DNA
• ER channels may have protected vital proteins
DNA
Figure 20.10
Page 335
infolding
of plasma
membrane
Theory of Endosymbiosis
• Lynn Margulis
• Mitochondria and chloroplasts are
the descendents of free-living
prokaryotic organisms
• Prokaryotes were engulfed by early
eukaryotes and became permanent
internal symbionts