the creation of the FIRST CELL

[Bill Nye Guy]

alright i have been reading alot about how the first living organism ( aka single celle) was created. I have been looking at alot of sites but i still have a few questions which i would be happy if you guys could solve.

 

Link Number 1- http://www.geocities.com/CapeCanaveral/Lab/2948/orgel.html This talks about how RNA needed to be present before Amino acids and protein in order for there to be the creation of the first cell. It also talks about how they tried to create the amino acids, protein and RNA in the lab. The one problem they had is they couldn't create RNA without the help of protein synthesis yet they said that they thought RNA had to come before protein in order for the cell to be created.

 

Link Number 2- http://www.lawrenceroberge.com/RNAWORLD.htm This is also some more insight into the idea that RNA should be created first, yet i am still confused about some of the ideas duscessed from both sites.....

 

 

 

-My main question concerns RNA. Both sites said that they thought RNA HAD to come BEFORE everything else ( DNA,Protein, AMino acids, etc), yet they had a hard time coming up with how RNA was created besides the idea that RNA was formed from a lower system or version.

 

-I was woundering if RNA could have been created after the proteins and still have helped in the birth of the first cell? If so how would the RNA been created and what would be its involvement in the creation of the first cell?

 

-I was also woundering if it was possible that something else besides RNA with the help of Proteins and Amino acids could help create the first cell? If so what would this thing be, how would it be created and what role would RNA play in it?

 

- My last question deals with the improtance of protein synthesis with the creation of DNA and thus the first cell. I amazed at the importance that protein played into the creation of both DNA and the first cell. From what i was taught in my classes, i was unaware that protein played as huge a role as both sites claim it did. Can someone possible explain how protein is that important to the birth of both the first cell and DNA?

 

 

I have been reading this material for awile know and have been poundering these questions for awile know. I would greatly appricate it, if someone can clairify and properly answer these questions. Thanks for the time all.

 

Also any comments, information,or updates on the topics suggested in the two sites would also be greatly appricated.

[LucidDreamer]

My main question concerns RNA. Both sites said that they thought RNA HAD to come BEFORE everything else ( DNA' date='Protein, AMino acids, etc), yet they had a hard time coming up with how RNA was created besides the idea that RNA was formed from a lower system or version.

-I was woundering if RNA could have been created after the proteins and still have helped in the birth of the first cell? [/quote']

Yes, I think this is a possibility. Self-replicating proteins have been found so a protein could have conceivably been the first polymer of life.

If so how would the RNA been created and what would be its involvement in the creation of the first cell?

RNA would have been created the same way it is today, by the enzymatic function of a protein. In this case the self-replicating protein would have had an alternate enzymatic site that created RNA. The second part of the question is difficult to answer but it would obviously have been involved in an enzymatic function, perhaps it would have been involved in the creation of proteins, like the function of RNA within a modern ribosome. Maybe the first element of life was a protein that created RNA that created protein.

 

-I was also woundering if it was possible that something else besides RNA with the help of Proteins and Amino acids could help create the first cell? If so what would this thing be, how would it be created and what role would RNA play in it?

How about a metal coenzyme like iron or copper that helped perform some sort of oxidation/reduction reaction? What about phospholipids and their ability to form compartments? What about carbohydrates and their ability to form various structures and attachments?

 

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My last question deals with the improtance of protein synthesis with the creation of DNA and thus the first cell. I amazed at the importance that protein played into the creation of both DNA and the first cell. From what i was taught in my classes, i was unaware that protein played as huge a role as both sites claim it did. Can someone possible explain how protein is that important to the birth of both the first cell and DNA?

The catalytic functions (facilitation of chemical reactions) of RNA are limited. However the possible chemical reactions that can occur with the help of proteins are almost limitless.

 

The chemistry of life depends on enzymes that perform various catalytic functions. Since enzymes are made of protein, proteins are essential to the chemistry of life. In order to harness energy, store energy, build structures, create gases or break down gases, etc. you need enzymes to facilitate the chemical reactions. The complex reactions involved in the replication of DNA and its transcription to RNA can only occur through the reactions that are made possible with protein enzymes.

[Bill Nye Guy]

wow thanks for all that information, it differently helped.

 

RNA would have been created the same way it is today, by the enzymatic function of a protein. In this case the self-replicating protein would have had an alternate enzymatic site that created RNA. The second part of the question is difficult to answer but it would obviously have been involved in an enzymatic function, perhaps it would have been involved in the creation of proteins, like the function of RNA within a modern ribosome. Maybe the first element of life was a protein that created RNA that created protein.

[/Quote]

 

So i am assuming that when the first RNA was created, the sugar, phosphates and the proteins ( along with the enzymes ) where all present in the "Chemical Soup" ( aka the chemical reactions found during the creation of the earth).

 

If these items were found in the chemical soup then it would be easy to understand how RNA could have been created before and after the proteins.

 

Thanks alot all!!!

[zyncod]

I don't know that there are actually any self-replicating proteins. The reason the "RNA world" hypothesis is so attractive is that each unit (nucleotide) of a self-replicating RNA can pair with its cogent partner (A<->U, C<->G). Therefore, as long as the RNA was palindromic, it would be very easy to self replicate. An example of this is:

5'-AAACGGCUUU-3' <--- The self-replicator

3'-UUUGCCGAAA-5' <--- Its offspring

However, amino acids have no such intrinsic ability to pair with one another, making a self-replicating protein very difficult. All the RNA would need to do was catalyze the bonds between the phosphates and hydroxyls on the nucleotides that paired with it. Given that ribozymes (catalytic RNAs) are already known, along with this intrinsic pairing ability in RNA, the formation of a self-replicating RNA seems almost inevitable given a ready supply of nucleotides. DNA also has this pairing ability, but the lack of a 2' hydroxyl on the sugar ring makes it less catalytic and thus less likely to self-replicate.

 

So what probably happened was:

1. The self-replicating RNA formed

2. The self-replicating RNA at some point started to associate with proteins for stability (RNA is a little volatile on its own).

3. The RNA acquired the ability to make proteins, maybe through a proto-ribosome

4. The RNA-protein complexes became enclosed in lipid membranes or micelles

5. The transition from RNA to DNA as the genetic material occurred (DNA is much more stable than RNA and thus better as a genetic storage medium).

6. Voila - a cell!

 

Steps 3 and 4 might have been reversed, but given the complexity of the DNA-->RNA-->protein mechanism, it is almost certain that by the time DNA came around, the self-replicator was surrounded by some sort of membrane in order to concentrate these various nucleotides and amino acids.

[LucidDreamer]

I don't know that there are actually any self-replicating proteins.

http://news.uns.purdue.edu/html4ever/981203.Chmielewski.ptds.html

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8700225&dopt=Citation