Molecular Evidence to Support Evolution

Molecular Machine
Molecular Machine
Protein Import by Mitochondria
Protein Import by Mitochondria

If a cell is irreducibly complex, this means that if the component parts are removed the cell ceases to function as a cell. This is one of the tenets of Intelligent Design. Recently in 2009, however, scientists have been able to show that a cell is composed of “molecular machines.” These molecular machines have component parts that function together to build complex cells. Irreducibly complex parts at the molecular level are actually cobbled together by simpler parts and put together as a whole.

What is Evolution?

Evolution is a gradual process in which a biological organism changes into a different and usually more complex form. Evolution works at the DNA level. This has been known for a long time. Darwin did not know it, but he was prescient enough to know that there were mechanisms that moved plants and animals to become what they are. One of his two most promising notions was adaptation to make a species survive (survival of the fittest). The second notion was natural selection. Darwin didn’t have the scientific tools that modern evolutionary scientists have, but now scientists have been able to provide proof that a simple system can build a complex system.

Simple Cells

As cells go, a eukaryote, or single-celled organism, possesses a nucleus and membrane-bound organelles. But bacteria, for example, which are prokaryotes, are simpler organisms and do not have a nucleus. The first eukaryotes had simple core machines created by importing pre-existing proteins. Over time, eukaryotes developed the potential for much greater complexity and diversity than prokaryotic cells. Some examples include mitochondria and chloroplasts. Mitochondria moreover, have their own DNA. Over time mitochondria has slowly been transferred to the better-protected nucleus.

Eukaryotes are more recent in life development than prokaryotes. Prokaryotes evolved sometime between 2.7 and 3.5 billion years ago. Eukaryotes, on the other hand, evolved sometime between 1.6 and 2.2 billion years ago. The earliest eukaryote fossils date around 1.2 billion years ago. They are found in the form of red algae, which is a type of seaweed.

Eukaryotes and Transport Mechanisms

Scientists focused on one specific molecular machine called the TIM complex. Its job is to transport proteins into mitochondria. Mitochondria are the powerhouse compartment of human cells. They produce energy for the cell. At a very early stage in evolution, mitochondria were derived from bacteria that lived within the first eukaryotic cells.

Thus the evolutionary sequencing stage is: first there were eukaryote that did not have mitochondria, then there was a transport mechanism, the TIM complex carried by bacteria, which entered and joined the eukaryote. Finally, the eukaryote has mitochondria.

Where Did the TIM Complex Come From?

The TIM complex is found in mitochondria and it contains a protein complex that is necessary for cell survivable. This complex is required for the import of ADP/ATP carrier (AAC), into the inner membrane.

Is there any evidence of the TIM complex in bacteria? The answer is no. Scientists looked at the bacterium Caulobacter crescentus. They did not find mitochondria or the TIM complex but found instead bacterial proteins that are related to several components of the mitochondrial TIM complex. Then they were able to establish that these bacterial proteins are not part of the protein transport machines.

Here is the sequence. First the eukaryote that did not have mitochondria, then there was a transport mechanism, the TIM complex that carries proteins into cells was carried by bacteria. Next, the TIM complex entered and joined the eukaryote. Finally, the eukaryote has mitochondria. Here is the finding: modern bacteria do not have the TIM complex, but they have components of the TIM complex still found in their membranes. Thus the eukaryote was added to mitochondria, whereas the prokaryotes were carriers of the TIM complex, but no mitochondria today have remnants of that TIM complex to show for it.

An “irreducibly complex” mechanism, the TIM complex, was put together as a transport mechanism that joined it to eukaryotes. This Tim Complex does not to exist in bacteria, but remnants of it are found there. This shows that an “irreducibly complex” mechanism in the final stage of development, was actually built up in parts.It evolved and this shows that evolution is still the best explanation for biological change.

References:

http://www.biology-online.org/dictionary/Eukaryote

http://www.biology-online.org/dictionary/Prokaryote

What is Evolution?

http://www.allaboutscience.org/what-is-evolution-faq.htm

Eukaryotes and Transport Mechanisms

http://tolweb.org/Eukaryotes/3

The TIM Complex

http://www.naontiotami.com/?p=807

http://www.cytochemistry.net/Cell-biology/mitoch3.htm

More by this Author


Comments 5 comments

RomerianReptile profile image

RomerianReptile 7 years ago

nice pub!


nicomp profile image

nicomp 6 years ago from Ohio, USA

"If a cell is irreducibly complex, this means that if the component parts are removed the cell ceases to function as a cell."

Which came first? DNA needs enzymes to replicate, but the enzymes are encoded by DNA. In other words, DNA makes enzymes and also needs enzymes to survive.

DNA also requires protection provided by the cell wall, but the cell wall is also encoded by the DNA. In other words, it takes DNA to provide the instructions to build a cell wall, but DNA needs a call wall in order to function.


nicomp profile image

nicomp 6 years ago from Ohio, USA

"An “irreducibly complex” mechanism, the TIM complex, was put together as a transport mechanism that joined it to eukaryotes. This Tim Complex does not to exist in bacteria, but remnants of it are found there. This shows that an “irreducibly complex” mechanism in the final stage of development, was actually built up in parts."

It shows no such thing. Finding remnants of a Tim Complex mechanism does not imply that the remnants morphed/evolved in to anything more complex. You can't make that logical leap.


ya mama 4 years ago

your mom and dad had a party an dyou came 9 months later


jerrygedorio 3 years ago

nice one!

    Sign in or sign up and post using a HubPages Network account.

    0 of 8192 characters used
    Post Comment

    No HTML is allowed in comments, but URLs will be hyperlinked. Comments are not for promoting your articles or other sites.


    Click to Rate This Article
    working