Transcript Heterotroph Hypothesis

Aim: How did life on earth begin?
How is life able to exist today?????
I. Heterotroph Hypothesis
A. Autotroph - An organism capable of synthesizing its
own food from inorganic substances, using light or
chemical energy. Green plants, algae, and certain
bacteria are autotrophs.
1. Carry out photosynthesis
6CO2 + 12H2O + sunlight ---> 6O 2 + C6 H12O 6 + 6H2 O
or...
carbon dioxide + water + sunlight ---> oxygen
+ carbohydrate + water
B. Heterotroph - An organism that cannot synthesize
its own food and is dependent upon complex organic
substances for nutrition. Animals are heterotrophs.
1. Carry out respiration
C6H12O6 + 6O2  6CO2 + 6H2O + energy
1 glucose + 6 oxygen = 6 carbon dioxide + 6 water + energy
respiration - process by which an organism exchanges
gases with its environment.
CO2 = Carbon
Dioxide
H2O = Water
O2 = Oxygen
C = Carbon
C6H12O6
= Glucose
H = Hydrogen
O = Oxygen
N = Nitrogen
Subscript indicates how
many molecules of the
particular element are
present.
Photosynthesis
6CO2 + 12H2O + sunlight
6O 2 + C6 H12O 6 + 6H2 O
Reactants
Yields
Products
C6H12O6 + 6O2
6CO2 + 6H2O + energy
Respiration
C. Early Earth Atmosphere
1. The early Earth atmosphere contained mostly
hydrogen, water, ammonia, and methane.
2. Stanley Miller and Harold Urey recreated early
Earth.
a. They filled a flask with hydrogen, methane,
ammonia and water to represent the atmosphere.
b. They passed electric sparks through the
mixture to simulate lightning.
c. The result: several amino acids (building blocks
of proteins) began to accumulate.
Over time, the molecules became more complex and
began to collaborate to run metabolic processes.
Eventually, the first cells came into being. These cells were
heterotrophs, which could not produce their own food and
instead fed on the organic material from the primordial
soup.
Heterotroph cells
Anaerobic cells – do not need oxygen to create energy
Release CO2 into atmosphere
Photosynthetic autotrophs
Release oxygen into atmosphere
Aerobic heterotrophs (anaerobic organisms die)