A CDK007 Production

The Origin of Life.

(Turn UP your Volume.)

Since the dawn of humanity, civilizations have created myths

to explain our origins.

Grounded not in fact, but in belief, the thousands of different creation myths

all share one common thread…

The Supernatural.

No human mind could conceive of a means of life originating through

purely natural processes.

Life only appears to come from life, therefore a natural origin was out of the question.

Before we continue let’s get one thing straight.

The origin of life, Abiogenesis,

has NOTHING

to do with the

Theory of Evolution.

Scientific theories are designed to explain a SPECIFIC set of facts.

You would not claim the theory of gravity is wrong because it doesn’t explain germs.

(that’s what Germ Theory is for)

Claiming evolution is wrong because it doesn’t explain the origin of life,

is like claiming an umbrella doesn’t work because it doesn’t predict

the paths of hurricanes.

Abiogenesis explains the origin of life…

Evolution explains how life changes once it already exists.

Creationists have made a number of arguments why they think abiogenesis is

wrong.

Here are the top 4.

Creationist Arguments Against Abiogenesis:

Argument 1Spontaneous generation

of complex organisms is impossible.

Spontaneous generation was actually scientifically tested and proven false in

1668 by Francesco Redi…

…in 1765 by Lazzaro Spallanzani…

…and in 1859 by Louis Pasteur…

…and has never been claimed by scientists since.…

Way to be current.

Creationist Arguments Against Abiogenesis:

Argument 2The probability of a single cell forming by chance is

1 in 1050,000.

Disregarding the fact that these numbers are made up…

…all it shows is that early life could not have been as complex as modern cells.

Creationist Arguments Against Abiogenesis:

Argument 3Taken from Ben Stein.

“Life was created by lightning striking a mud puddle”

And that’s just silly.

Actually, there is only one book that claims life was formed from dirt.

Creationist Arguments Against Abiogenesis:

Argument 4The 1953 Miller-Urey

experiment did not create life.

This is like claiming it’s impossible to fly to the moon simply because

the Wright brothers didn’t.

The early earth had orders of magnitude more:

Time,Space,

Complex Chemistry, &Environmental Conditions

So what can science tell us about the origin of life?

This video is a summary of work by Dr. Szostak

Professor at

Harvard Medical School

We know from experiments and observations made in the fields

of Astronomy,

Chemistry,

Geology,

and Meteorology that…

…the early pre-biotic earth was filled with organic molecules,

the building blocks of life.

Organic molecules are actually quite common in space.

We also know from the creationist arguments discussed earlier, that early life must have been extremely simple…

X

…meaning NO complex protein machinery.

X

Modern cells separate themselves from the environment with a lipid bilayer.

The problem with modern phospholipids is they are too good at what they do.

They form a nearly impenetrable barrier.

Modern cells must use proteins to move molecules across their surface.

But life didn’t have to start with modern

chemicals!

The pre-biotic environment contained many simple fatty acids.

Under a range of pH they SPONTANEOUSLY form stable vesicles.

And they are permeable to small organic molecules…

…meaning no complex proteins are required to get stuff in.

When a vesicle encounters free fatty acids in solution, it will incorporate them.

Eating and growth are driven purely by thermodynamics.

When a vesicle grows it adopts a tubular branched shape…

Surface area grows faster than volume.

…which is easily divided by mechanical forces (waves, currents, rocks…)

During mechanical division, none of the contents of the vesicle are lost.

So far, with naturally occurring simple fatty acids, we have a vesicle that can

spontaneously grow and divide.

So what about the genetic material.

Again, modern nucleotides are too stable and require complex protein machinery to replicate.

The pre-biotic environment contained hundreds of types of different

nucleotides (not just DNA and RNA).

(All it took was 1 to self polymerize.)

Recent experiments have shown that some of these are capable of spontaneous polymerization, such as Phosphoramidate DNA.

Monomers will base pair with a single stranded template and self ligate.

Hydrogen BondsBase Pair

Covalent BondLigation

They can also polymerize in solution, and spontaneously form new

templates, or extend existing templates.

No special sequences are required, it’s just chemistry. 

So far we have lipid vesicles that can grow and divide,

and nucleotide polymers that can self replicate, all on their own.

But how does it become life?

Here’s how.

Our fatty acid vesicles are permeable to nucleotide

monomers, but not polymers.

Once spontaneous polymerization occurs within the vesicle, the polymer is trapped.

Floating through the ocean, the polymer containing vesicles will encounter convection currents…

… such as those set up by hydrothermal vents.

(fatty acid vesicles are stable under near boiling conditions)

The high temperatures will separate the polymer strands and increase the

membrane’s permeability to monomers.

Once the temperature cools spontaneous polymerization can occur. And the cycle repeats.

Here’s where it gets cool.

The polymer, due to surrounding ions, will increase the osmotic pressure within the

vesicle, stretching its membrane.

A vesicle with more polymer, through simple thermodynamics, will “steal”

lipids from a vesicle with less polymer.

This is the origin of competition.

They eat each other.

A vesicle that contains a polymer that can replicate faster,

will grow and divide faster,

eventually dominating the population.

-Monomers spontaneously polymerize and copy any template

-Heat separates strands, increases membrane permeability to monomers

-Polymer backbones attract ions increasing osmotic pressure

-Pressure on the membrane drives its growth at the expense of nearby vesicles containing less polymer

Let’s Review: -Monomers diffuse into a fatty acid vesicle

-Mechanical forces cause vesicles to divide

-Daughter vesicles inherit polymers from the parent vesicle

-Polymer sequences that replicate faster will dominate the population…

Let’s Review: -Vesicles grow into tubular structures

Thus beginning evolution!

Early genomes were completely random and therefore contained

NO information.

It was their ability to spontaneously replicate,

irrespective of sequence, that drove growth and division

of the fatty acid vesicles.

Any mutation that increases the rate of polymer replication

would be selected for.

And as I’ve shown before

Mutation +

Natural Selection=

Increased Information

Early beneficial mutations would include:

Change sequence to contain only the most common

nucleotides.

Early beneficial mutations would include:

Don’t form secondary structures that block replication.

X

Early beneficial mutations would include:

Form sequences that are stable yet separate easily.

X

Early beneficial mutations would include:

Form secondary structures that show some enzymatic activity.

Just like RNA, early nucleotides could both store information and

function as enzymes.

Early polymer enzymes would:

Enhance replication

Early polymer enzymes would:

Use high energy molecules in the environment (near thermal vents) to recharge monomers.

Early polymer enzymes would:

Synthesize lipids from other molecules in the environment.

Early polymer enzymes would:

Modify your lipids so they don’t leave your membrane.

And that’s it.

A simple 2 component system that SPONTANEOUSLY forms in the pre-biotic environment…

…can eat, grow, contain information, replicate,

and EVOLVE…

…simply through thermodynamic, mechanical,

and electrical forces.

No ridiculous improbability…

No supernatural forces…

No lightning striking a mud

puddle…

Just Chemistry.

Think about it.