Download Life Origins

Life Origins
Theories of where life came from
Spontaneous generation
 Called
abiogenesis
 The Idea that life can come from Non-Life.
 Ex.
Mice appear in a jar of grain covered
by a dirty shirt
 abiogenesis
Francisco Redi
 Proved
that maggots do not
spontaneously form on meat
Redi’s experiment
jar  maggots
 Sealed jar  no maggots
 Cloth covered jar (air)  no maggots
 Open
Spallanzani
 Proved
microorganisms could not grow
without particles from air settling in broth
 Open  grew bacteria
 Closed  no bacteria
Louis Pasteur
 Improved
Spallanzani’s experiment by
using a curved swan neck flask
Pasteur's experiment
 Allowed
air, but no dust into broth.
 No microorganisms grew
 Until he broke off neck
So where did life come from?
 Theories
A - Spontaneous formation
in primordial soup
 The
theory that just the right combination
of elements, compounds and energy
formed the first biomolecules which then
assembled itself into first life
 One Time Event
B - Panspermia
 Theory
that life is of Extra Terrestrial origin
 1) Organic compounds brought on meteor
 2) Aliens “seeded” life
C – Life Was Created
 Creationism
- The belief that a supreme
being or God created life from non-life in
the beginning
 Intelligent design - The theory that life is
so complex it indicates a designer behind
its formation (not necessarily God)
Origin of the universe
Bang Theory – The idea that the
universe all started in the same place and
expanded outward
 Big
Big Bang was 15 Billion years ago
(maybe 13 -14 Billion )
Evidence of big bang
The Universe is expanding.
Proved by two things
 Red Shift of galaxies
 Background radiation of 3 degrees Kelvin
3 degrees Kelvin
 Radio
telescope (in Holmdel NJ) picked up
radio waves emitted from the left over heat
energy from the big bang. 1965
Red shift
When the lines in a
galaxy’s or star’s
spectrum shift into the
red part of the spectrum,
as it moves away.
 Shows us that all stars
and galaxies are moving
away from a central point
Solar system formation
 Large
clouds of gas and dust were pulled
together due to gravity. The pressure
causes stars to form and ignite.
 Planets are made of extra debris left over
Solar System
 Solar
system formation is estimated at 5
billion years ago
 The estimated age of earth 4.6 billion
years
Earth’s atmosphere
 Came
from volcanoes emitting gas
 Also may have come from comets
Earth’s early atmosphere
 Contained
NH3, H2, H2O and CH3
 Maybe Oxygen? Sunlight releases O2 from
H2O
 O2 causes oxidation (breakdown) of
biomolecules
Oparin’s hypothesis
 He
believed that the early
atmosphere contained
ammonia, hydrogen gas,
water vapor and methane
 Warm temperatures and
lightning could have
caused organic
compounds to form
Miller – Urey experiment 1953
 Tried
to recreate
original conditions
 Formed some amino
acids
 Problems:
-Too much O2 oxidizes
-Too hot, denatures
Mostly discredited
EVIDENCE Possibly Supporting
spontaneous origin of life
Microspheres 1957
 Fox
produced tiny microspheres made of
amino acids that would reproduce by
budding , but DID NOT pass on any
genetic information
Coacervates
 Tiny
formations of molecules, mostly lipids,
held together by hydrophobic forces.
 Maybe these forces held biomolecules
together long enough to form life
Ribosymes


RNA that can act as an enzyme
Would help before proteins first made
Cyanobacteria
 Possibly
first photosynthetic bacteria
 Produced O2 for atmosphere
 O3 (Ozone)
Endosymbiosis theory
 Mutually
beneficial relationship where one
prokaryote lives in another forming Eukaryote
 Explains why mitochondria and Chloroplasts
have DNA