Miller – Urey Experiment

Miller Experiment

The focus of this experiment was to determine if amino acids could be produced by re-creating early Earth conditions. This experiment was done at the University of Chicago in 1953 by Stanley Miller. The experiment consisted of a boiling flask that was attached to a collecting trap that connected to a condensing column. This released steam that went to another bottling flask. Inside this flask were an anode and a cathode, which were connected to a power supply. This created an arc which was to simulate lightning from the early Earth’s atmosphere. The steam would condense and return to the original flask, where it was reheated and run through the cycle over and over again.

Harold Urey, Nobel laureate, was Miller’s doctoral advisor and Miller pulled heavily from his theories. Miller used a hydrogen rich formula that also included water ammonia and methane. The experiment was allowed to run for a week. Miller’s experiment showed that as much as 10 – 15% of the carbon was formed into organic compounds.  Miller’s experiment showed that amino acids could be formed under conditions that could have existed on early earth.

Skepticism about this experiment has come about in recent years because the general consensus of what the pro atmosphere of earth was has changed since the experiment took place. The current belief is that the early atmosphere of earth contained very little hydrogen.  That the hydrogen on earth at that time would have boiled off into space.  The general view is that this early atmosphere would’ve consisted of carbon dioxide, water vapor and nitrogen. If you reproduce the experiment under these conditions you get cyanide and formaldehyde.

Although these are organic molecules, they certainly do not support living cells, rather having a completely opposite effect.  Formaldehyde is so toxic that it’s not even allowed in many labs. Just opening a bottle can destroy proteins. Cyanide gas has been used through history to execute prisoners by gassing them to death. Mixing the two together creates embalming fluid.

In 1995 Science magazine said that most experts now dismiss the experiment because “the early atmosphere looked nothing like the Miller Urey simulation”.

Another objection to this experiment was the continuous cycle that the elements were put through. Although it is believed that the early Earth did have frequent lightning storms, it would not have produced the amount of amino acids that the Miller experiment did, however, it still could have produced amino acids.

Converting Amino Acids Into Protein Molecules

From the video tutorial we get a basic understanding of how amino acids are converted into protein molecules. As the video stated, amino acids join together in long chains. These chains are a combination of many different kinds of amino acids in different orders.  The order of these amino acids will determine what the protein molecule can be used for.

A small protein cell will consist of 100 amino acids, with a large protein molecule consisting of over 1000. The size and shape of the protein molecule determines what it’s good for, kind of like a key for a lock.

The body uses hundreds of different kinds of protein molecules to accomplish different tasks.  Some types of protein molecules are used for brain cells. Others are used for blood cells or muscles; the list goes on and on.  There are hundreds of different kinds of proteins required to perform the thousands of different tasks required for the body to live.

The simplest forms of life require hundreds of different kinds of proteins as well and all would have had to have been available to create the firest cell. Even if all these obstacles can be overcome there’s still the conundrum of infusing the protein molecules with DNA.

Protein Molecules to Living Cells

DNA double helix molecules and chromosomes

In our process of going from amino acids to living cells we’re leaving out literally thousands of steps that would be required to get from amino acids to living cells.

As opposed to trying to wade through all of this, let’s make a challenge.

Place a sterile balanced salt solution in a test tube and put a single living cell in it. Rupture the cell allowing the materials inside the cell to leak into the solution.

Now you have all the materials required to make a living cell.  You are vastly ahead of anything that the Miller – Urey experiment had to offer.

The challenge is to take the materials within the test tube and convert them into a living cell.

I know of no biologist in the world who would take on this challenge.  If any scientist does succeed at doing this, no matter how complex the process, they will find their place in history as one of the greatest scientists ever to have lived!

DNA Replication

Miller – Urey Experiment Image

3 thoughts on “Miller – Urey Experiment

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