1. The spontaneous origin of life on Earth
Branched Timeline Activity
Complete the diagram on the next slide

2. Spontaneous origin of life
Four essential processes;
the non-living synthesis of simple organic molecules
the assembly of these molecules into polymers
the origin of self-replicating molecules that made inheritance possible
the packaging of these molecules into membranes with an internal chemistry different from their surroundings.

3. UV radiation & lightning
the Earth”s atmosphere contained
■ nitrogen, water vapour and carbon dioxide;
■ smaller amounts of methane, ammonia, carbon monoxide, sulphur dioxide, hydrogen sulphide and hydrogen cyanide.
Describe the evidence from Miller and Urey’s experiments ……………………………………………………………………………………………………
Non-living synthesis of organic molecules
What recent evidence suggests that Comets
brought complex organic
Compounds to Earth ?
…………………….
……………………
…………………....
complex organic compounds
e.g. glucose, ……….…… …
…………add some of your own ……

4. Formation of Protobionts
Identify what is needed for each of the steps below…
The polymers exist in small packages which become different from the surroundings
Larger molecules
Polymers, big enough to have biological functions
Inheritance of the molecules is now possible
Organic Molecules If
some
of the
organic
molecules
function as
……………
Causing
…………………. If
some
molecules
form primative
………. ………..
That hold the
Polymers in one place
If a
polymer
of RNA is
surrounded by
a ………………
and it replicates
and then the membrane
…………………….
Into two loops..

5. Summary – what you have to know
Outline the experiments of Miller and Urey into the origin of organic compounds.
State that comets may have delivered organic compounds to Earth.
Discuss possible locations where conditions would have allowed the synthesis of organic compounds.
Outline two properties of RNA that would have allowed it to play a role in the origin of life. Include the self-replicating and catalytic activities of RNA
State that living cells may have been preceded by protobionts, with an internal chemical environment different from their surroundings. Examples of Protobionts include coacervates and microspheres.
ToK –"falsification of hypothesis" is a problem for many of these theories. Scientists can’t actually travel back in time 4000 million years!
The ability to test if the hypothesis is false is an essential ingredient of Science.
The idea of Creation – is not Scientific because it can never be tested.