Download How Life Began Notes: These are notes Mr. Ward took while

How Life Began Notes:
These are notes Mr. Ward took while watching How Life Began.
INTRODUCTION: How did life began?
It is easier to figure out what happened just before and just after life began.
All cultures have asked the question of where did we come from?
How did nonliving matter evolve into living organisms.
There are different hypotheses:
Warm pools of water full of chemicals: Did life form in a watery primordial soup?
Deep Sea Hydrothermal Vents: Could life have formed in total darkness in extreme temperatures and
pressures at the bottom of the ocean?
Clay Minerals: Did life form on the electrically charged surfaces of clay minerals?
However life began, all living things are made of elements
Old ideas of elements: Aristotle earth, air, water, fire and quintessence (the life force)
Aristotle believed that “quintessence” was linked to the origin of life.
Life uses only a few of the over 100 elements known. The most common elements in life are the
“CHON” elements: C=Carbon, H=Hydrogen, O=Oxygen, N=Nitrogen
Carbon is very important. It can easily bond with almost any element, including other carbon atoms.
Compounds with carbon in them are called “Organic Compounds” or “Organic Molecules”.
Carbon molecules are extremely diverse: There are over 10 MILLION known Organic Compounds.
Water is also important to life. It isn’t an organic compound, but is liquid from 0C (32F) to 100C
(212F). This liquid is a good place for organic molecules to come together and form new, more
complex organic molecules.
Chemicals use energy to come together into new molecules.
The Cell: Living things are made of cells.
We don’t yet know how organic compounds become a cell.
THREE THINGS ARE NECESSARY FOR A CELL:
However, energy is key to this process.
Life needs to have a flow of energy in and out of cells:
Metabolism is the ability to use and organize energy.
Sugars and Carbohydrates store energy and are used in the process of metabolism.
Cells also need a boundary to keep good stuff in and unwanted stuff out.
Membranes are made of “lipids” and are what cells use as a boundary.
Membranes are a compartment to keep the cell in.
Cells also need a way to copy themselves.
Amino acids connect together to make proteins. One combination is called DNA. Cells use DNA
to copy themselves with.
Emergence: One more thing is needed. Complex combinations of organic molecules must become
organized into an actual cell. This is where the idea of “Emergence” comes in….
Emergence is when the laws of nature organize complex things into something more orderly.
Examples: Birds flocking together, Ripples in sand at the beach, Consciousness out of a large
collection of nerve cells.
Emergence is not magical or random. It is the result of the laws of physics and chemistry and
mathematics as well as the flow of energy.
Life in the extreme conditions of the early Earth.
Early Earth: molten surface, heavy bombardment by meteors and comets.
Fossils of early life show that life appeared as soon as the Earth could support it though (as soon as
there was solid crust for life to be on and the earth was cool enough for water to be liquid).
[Mr. Ward’s note: The oldest fossils of cells is 3.5 GA, and there are fossils that are probably
bacterial waste that are 3.85 GA. By studying DNA, scientists now put the origin of life between
4.2 and 4.0 GA ago.]
Where to learn about life in such extreme conditions?
Look for “Extremophiles” (lovers of extreme conditions) in hotsprings, deep underground and in
deep ocean “black smokers”
Example: Mono Lake is very salty, alkali (opposite of acid), and full of poisons like arsenic.
Purple and Green Bacteria grow in the 50C (122F) water.
Early Life changed their environment.
Early Earth would be murder to complex life.
Weak sun (but making lots of Ultraviolet radiation) and no oxygen. Early life probably didn’t use
photosynthesis and couldn’t use oxygen for energy. Instead, had to eat rocks and convert the
chemicals in rocks into energy for their metabolism.
Early life changed the Earth in ways that made it possible for complex life to evolve.--> Made an oxygenrich atmosphere.
Single celled organisms called cyanobacteria formed bacterial slime piles called “Stromatolites”
Earliest stromatolites ate rocks.
Later, they evolved photosynthesis and produced an atmosphere with oxygen in it. Oxygen is a waste
product from photosynthesis.
Microbes dominate Earth
For the first 80 to 85% of the Earth’s history, microorganisms are the dominant life on earth.
Amoeba is used as an example for the three key ingredients for life:
Metabolism, Membrane boundaries, and DNA for copying.
[skipped parts of video—to be seen later—video picks up with a quick tour of bacteria living in your
digestive system….]
Exploring How Life Began
Early ideas: Spontaneous generation: Life coming from non-living things
Example 1 Sunlight on wheat  Spontaneous generation of mice.
Example 2 Dirty cloth and wheat in an open jar  Again, spontaneous generation of mice.
Francesco Redi’s experiment to test the question: “Do maggots spontaneously generate from
meat if it is left out in the heat?” Meat is covered with a cloth, no maggots appear on the meat,
but flied did land on the cloth and laid eggs there.
John Needham, a Catholic Priest in England, was a supporter of Spontaneous Generation. He
boils mixtures of water and organic matter. He puts it in jars sealed with wax and the liquid gets
cloudy with microbes. Problem: His seal was not good enough to keep out microbes in the air.
He believes in something called “vital atoms”
Lazarus Spallanzani tries the same experiment, but melts the glass opening of his beaker to
completely seal his mixtures. He boiled it, and no microbes show up.
Louis Pasteur sets up an experiment where air is allowed in, which microbes are not. The
mixture doesn’t have any microbes. His experiment is very successful in destroying the
spontaneous generation idea.
Problem: Life had to come from nonliving things at least once! How?
Darwin proposes a warm pool of water and organic chemicals as a place where life may have evolved.
The oceans were like a large warm pool full of organic chemicals in the early Earth.
But could this be tested today?
YES: Stanley Miller, a 22 year old graduate student, creates an experiment to see how oceans,
the early earth atmosphere, and energy (electricity) interact. Would organic compounds form?
After a few days, very complex organic compounds DID FORM: Amino Acids, which are the
building blocks of proteins and DNA.
Problem: Early Earth atmosphere was different than Miller thought it was. Very little methane, lots of
carbon dioxide.
Scientists explore other possibilities:
Chemicals of life from outer space?  Meteorite falls in Australia in 1969, and is full of amino acids
and organic molecules like lipids which form into membrane like boundaries.  This means the
building blocks of life existed in space before the Earth formed!
This information leads to “Panspermia”. This is the theory that life or at least the building blocks
of life came from outer space.
Problem: Panspermia doesn’t solve the problem of how life began (wherever it began).
New and Improved Primordial Soup:
Stanley Miller tries again using a corrected early Earth atmosphere. It still produced amino acids, which
supported the “primordial soup” model.
Other places?
Deep underground in a hot wet environment
Deep undersea in a hot, high pressure environment around hydrothermal vents (black smokers)
Experiment: High temperature, high pressure created. Vesicles are created: membrane chemistry!
Clay? Clay has electrical charges on its surface. This attracts organic molecules so there are more of
them together in one place. This speeds up chemical changes. In some experiments, Clay helped to
make RNA—Ribonucleic Acid, a copying molecule (a building block of DNA—Deoxyribonucleic Acid)
IT’S ALIVE! IT’S ALIVE:
Creating artificial cells in a lab? Several research teams around the world are working to create living
cells in a lab.
Video predicts that we may soon create life in a lab.
However, creating life in a lab will not show us how life was formed. It will only show us how life might
have been formed.