Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 113 (8748 total)
Current session began: 
Page Loaded: 05-23-2017 10:52 AM
415 online now:
Chatting now:  Chat room empty
Newest Member: kmastes01
Post Volume:
Total: 808,865 Year: 13,471/21,208 Month: 2,953/3,605 Week: 295/933 Day: 37/154 Hour: 9/6

Announcements: Reporting debate problems OR discussing moderation actions/inactions


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Prev1
2
34567Next
Author Topic:   Could RNA start life?
Dr Adequate
Member
Posts: 15927
Joined: 07-20-2006
Member Rating: 3.8


(4)
Message 16 of 105 (682691)
12-04-2012 5:14 PM
Reply to: Message 1 by dayalanand roy
12-04-2012 12:50 AM


Nucleic acids are the information storage system of life. When there was no life, why did nature invent a storage system to store the information about sometning (Life) which was still not existent, and hence there was no information to store. Can we suppose the invention of a floppy disk, a CD or a pen drive before the invention of computer? Can we suppose the invention of bank before the invention of money?

Can we imagine that nature "invented" chalk and slate before the invention of writing? Yes. Yes we can. How about clay and reeds, as were used by the Babylonians? Yup. Birch bark and sharp pieces of flint? Yup. Animal hide and oak galls? Yup.

Analogies are tricky things. I recommend that you think about RNA by actually thinking about RNA rather than about things such as floppy disks which RNA vaguely reminds you of.


This message is a reply to:
 Message 1 by dayalanand roy, posted 12-04-2012 12:50 AM dayalanand roy has responded

Replies to this message:
 Message 27 by dayalanand roy, posted 12-06-2012 6:11 AM Dr Adequate has not yet responded

  
crashfrog
Inactive Member


Message 17 of 105 (682695)
12-04-2012 6:00 PM
Reply to: Message 15 by RAZD
12-04-2012 4:48 PM


Re: abiogenesis - last stages?
Life certainly evolved out of spontaneously occurring chemistry, but it wouldn't be life until the chemistry was controlled and not spontaneous. Right?

Why?

Well, and again this could just be me, but the "why" is because that's what I think life is. I can mix potassium chlorate and gummi bears in a reaction vessel on my countertop, and that reaction is (incredibly) spontaneous, but it would be absurd to describe it as "alive", or even as a form of metabolism even though when I eat a gummi bear, a very similar reaction is occurring. Why? Because all that energy is being wasted, it's all heat and light and loss of entropy.

That, to me, is the difference between a reaction between potassium chlorate and hydrocarbons on the countertop and a reaction between potassium chlorate and hydrocarbons occurring in the cell of some putative clorate-based "gummi bear-vore" - the difference between chemistry that occurs spontaneously and chemistry that occurs spontaneously and is exploited. And I don't see how you get to the exploitation part, chemically-speaking, without mediating and controlling the reaction via catalysis. Otherwise you don't have life (or even proto-life) you just have chemistry.


This message is a reply to:
 Message 15 by RAZD, posted 12-04-2012 4:48 PM RAZD has acknowledged this reply

  
Dr Jack
Member
Posts: 3500
From: Leicester, England
Joined: 07-14-2003


Message 18 of 105 (682741)
12-05-2012 6:47 AM
Reply to: Message 15 by RAZD
12-04-2012 4:48 PM


Re: abiogenesis - last stages?
Both replication and metabolism -- replication needs raw materials being consumed to make the next (imperfect) copy. This would likely be enclosed in a lipid shell, so we have a ways to go before getting back to the "first" system\aspect of life.

How are you going to have replication without catalysis?


This message is a reply to:
 Message 15 by RAZD, posted 12-04-2012 4:48 PM RAZD has acknowledged this reply

  
Dr Jack
Member
Posts: 3500
From: Leicester, England
Joined: 07-14-2003


(1)
Message 19 of 105 (682742)
12-05-2012 6:59 AM
Reply to: Message 1 by dayalanand roy
12-04-2012 12:50 AM


Life is chemicals, not purposes
As we know, still majority of evolutionists believe in an RNA world hypothesis.

I wouldn't go as far as 'believe in' but, yes, most relevant scientists consider RNA world a probable step in the origin of life.

However, I have a problem in imbibing this theory. Nucleic acids are the information storage system of life.

Here, I'm afraid, you've fallen for the mistake of thinking that the simplified version presented to school children is the reality. The description of DNA as a "storage system" is poor enough, but for RNA it's simply wrong.

DNA is, in a sense, structurally boring. For the most part, it forms double strands that twist into helices. These helices are largely chemically uninteresting. There are no known occurrences of DNA acting enzymatically, and it's hard to think that it could do so. RNA is different, being single stranded it is free to twist into complex three-dimensional shapes. These three dimensional shapes are diverse enough to act as enzymes (biological catalysts) for a wide range of biologically important reactions. We know this to be the case because key roles in modern cells are still carried out by RNA enzymes (aka 'ribozymes').

This is why scientists think RNA world is so compelling an idea. In RNA world there is no dichotomy between "storage" and "enzyme" molecules; the two are one and the same: RNA. RNA shares the relative ease of copying that DNA has but combines it with much of the enzymatic capability of proteins.

Properly understood then, RNA world explains the objection you've raised.


This message is a reply to:
 Message 1 by dayalanand roy, posted 12-04-2012 12:50 AM dayalanand roy has responded

Replies to this message:
 Message 20 by Genomicus, posted 12-05-2012 10:08 AM Dr Jack has responded
 Message 26 by dayalanand roy, posted 12-06-2012 6:08 AM Dr Jack has not yet responded

  
Genomicus
Member
Posts: 815
Joined: 02-15-2012
Member Rating: 4.7


(1)
Message 20 of 105 (682754)
12-05-2012 10:08 AM
Reply to: Message 19 by Dr Jack
12-05-2012 6:59 AM


Re: Life is chemicals, not purposes
There are no known occurrences of DNA acting enzymatically...

One of the cool things about biology is that it's unpredictable. Deoxyribozymes have, in fact, been discovered. See, e.g., "In vitro selection, characterization, and application of deoxyribozymes that cleave RNA."


This message is a reply to:
 Message 19 by Dr Jack, posted 12-05-2012 6:59 AM Dr Jack has responded

Replies to this message:
 Message 21 by crashfrog, posted 12-05-2012 10:23 AM Genomicus has not yet responded
 Message 23 by Dr Jack, posted 12-05-2012 2:45 PM Genomicus has responded

  
crashfrog
Inactive Member


Message 21 of 105 (682761)
12-05-2012 10:23 AM
Reply to: Message 20 by Genomicus
12-05-2012 10:08 AM


Re: Life is chemicals, not purposes
Oo, oo, let me try one! "There are no naturally-occurring Diels-Alderases."
This message is a reply to:
 Message 20 by Genomicus, posted 12-05-2012 10:08 AM Genomicus has not yet responded

  
ringo
Member
Posts: 13017
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 3.4


(4)
Message 22 of 105 (682809)
12-05-2012 1:27 PM
Reply to: Message 1 by dayalanand roy
12-04-2012 12:50 AM


dayalanand roy writes:

When there was no life, why did nature invent a storage system to store the information about sometning (Life) which was still not existent, and hence there was no information to store.


Sometimes "information" is just an accident. When an animal leaves tracks in the snow, they contain information about what kind of animal he was, which direction he was going, how fast he was going etc. But he didn't invent snow just to convey that information.

Information is only information when it's used as information.


This message is a reply to:
 Message 1 by dayalanand roy, posted 12-04-2012 12:50 AM dayalanand roy has responded

Replies to this message:
 Message 25 by dayalanand roy, posted 12-06-2012 5:52 AM ringo has responded

  
Dr Jack
Member
Posts: 3500
From: Leicester, England
Joined: 07-14-2003


Message 23 of 105 (682817)
12-05-2012 2:45 PM
Reply to: Message 20 by Genomicus
12-05-2012 10:08 AM


Re: Life is chemicals, not purposes
One of the cool things about biology is that it's unpredictable. Deoxyribozymes have, in fact, been discovered. See, e.g., "In vitro selection, characterization, and application of deoxyribozymes that cleave RNA."

Excellent! Thank you, Genomicus (Link for the interested)

No naturally occurring deoxyribozymes yet discovered, though, and the process under which they were identified and determined to catalytically is quite artificial. None the less: I was wrong; always good to learn new things.


This message is a reply to:
 Message 20 by Genomicus, posted 12-05-2012 10:08 AM Genomicus has responded

Replies to this message:
 Message 24 by Genomicus, posted 12-05-2012 10:42 PM Dr Jack has not yet responded

  
Genomicus
Member
Posts: 815
Joined: 02-15-2012
Member Rating: 4.7


Message 24 of 105 (682920)
12-05-2012 10:42 PM
Reply to: Message 23 by Dr Jack
12-05-2012 2:45 PM


Re: Life is chemicals, not purposes
Excellent! Thank you, Genomicus...

You're welcome

You are indeed correct in pointing out that there are no known naturally occurring DNA enzymes. Although I do not find the RNA world scenario very compelling, I wonder if there is any literature on the possibility of DNA enzymes playing a role in the RNA world hypothesis.


This message is a reply to:
 Message 23 by Dr Jack, posted 12-05-2012 2:45 PM Dr Jack has not yet responded

  
dayalanand roy
Junior Member (Idle past 993 days)
Posts: 18
Joined: 11-27-2012


Message 25 of 105 (682937)
12-06-2012 5:52 AM
Reply to: Message 22 by ringo
12-05-2012 1:27 PM


Re RNA
Thank U. I admit that my thinking is somewhat biased towards seeking a purpose in life due to the spiritual background in which I am brought up. However, the difference between the animal trail in snow and RNA is that we have to derive information from the former and it is a passive information, but RNA is solely a copy, and an active copy of information, whether we derive or not, it will deliver its information to the protein synthesising machinery. It is an information highly specific and written in highly coded form. Yet, I have high regards for your message. Thanks and regards
Dayala
This message is a reply to:
 Message 22 by ringo, posted 12-05-2012 1:27 PM ringo has responded

Replies to this message:
 Message 28 by New Cat's Eye, posted 12-06-2012 10:56 AM dayalanand roy has not yet responded
 Message 29 by Taq, posted 12-06-2012 12:19 PM dayalanand roy has acknowledged this reply
 Message 30 by ringo, posted 12-07-2012 2:13 PM dayalanand roy has acknowledged this reply

    
dayalanand roy
Junior Member (Idle past 993 days)
Posts: 18
Joined: 11-27-2012


Message 26 of 105 (682938)
12-06-2012 6:08 AM
Reply to: Message 19 by Dr Jack
12-05-2012 6:59 AM


Re: Life is chemicals, not purposes
Many thanks
It depends on us to recognise purpose in chemicals. Someone can say that this message is alphabets, not a message. Some other can see a purpose in these alphabets. And even if life is not a purpose,it is of course a result. A beutiful result. This why we are looking up for the causes of these results. My sole purpose is to keep our minds open for alternative theories.regards. dayala

regards


This message is a reply to:
 Message 19 by Dr Jack, posted 12-05-2012 6:59 AM Dr Jack has not yet responded

    
dayalanand roy
Junior Member (Idle past 993 days)
Posts: 18
Joined: 11-27-2012


Message 27 of 105 (682940)
12-06-2012 6:11 AM
Reply to: Message 16 by Dr Adequate
12-04-2012 5:14 PM


Re RNA
Thanks for your comments. regards. dayala
This message is a reply to:
 Message 16 by Dr Adequate, posted 12-04-2012 5:14 PM Dr Adequate has not yet responded

    
New Cat's Eye
Member
Posts: 11346
From: near St. Louis
Joined: 01-27-2005
Member Rating: 2.2


(2)
Message 28 of 105 (682963)
12-06-2012 10:56 AM
Reply to: Message 25 by dayalanand roy
12-06-2012 5:52 AM


Re: Re RNA
However, the difference between the animal trail in snow and RNA is that we have to derive information from the former and it is a passive information, but RNA is solely a copy, and an active copy of information, whether we derive or not, it will deliver its information to the protein synthesising machinery.

But its just chemistry. In a simliar way, if you distill salt water then the sodium and chlorine ions will deliver their "information" to the structure of the complex salt crystals that will form.

Really, these types of reactions have no option but to react in the way that they do. They're spontaneous. RNA doesn't have any "driver", its just a chemical reaction.


This message is a reply to:
 Message 25 by dayalanand roy, posted 12-06-2012 5:52 AM dayalanand roy has not yet responded

  
Taq
Member
Posts: 6413
Joined: 03-06-2009
Member Rating: 4.3


(1)
Message 29 of 105 (682991)
12-06-2012 12:19 PM
Reply to: Message 25 by dayalanand roy
12-06-2012 5:52 AM


Re: Re RNA
However, the difference between the animal trail in snow and RNA is that we have to derive information from the former and it is a passive information, but RNA is solely a copy, and an active copy of information, whether we derive or not, it will deliver its information to the protein synthesising machinery.

The type of information you are talking about is no different than the type of information in any chemical reaction. The information contained in RNA is it's physical and chemical properties. We can not replace RNA with a piece of paper with tiny letters written on it and expect the same result.

In human written language the letters carry the information. In biology, the information is the ink and paper.


This message is a reply to:
 Message 25 by dayalanand roy, posted 12-06-2012 5:52 AM dayalanand roy has acknowledged this reply

  
ringo
Member
Posts: 13017
From: frozen wasteland
Joined: 03-23-2005
Member Rating: 3.4


Message 30 of 105 (683108)
12-07-2012 2:13 PM
Reply to: Message 25 by dayalanand roy
12-06-2012 5:52 AM


Re: Re RNA
dayalanand roy writes:

However, the difference between the animal trail in snow and RNA is that we have to derive information from the former and it is a passive information, but RNA is solely a copy, and an active copy of information, whether we derive or not, it will deliver its information to the protein synthesising machinery.


The information in the snow is there whether whether anybody uses it or not; same with the RNA. It can be used for some purpose "because it's there". It isn't necessary for somebody or something to put it there for that purpose.

Sometimes necessity is the mother of invention but other times new uses are found for an existing invention.


This message is a reply to:
 Message 25 by dayalanand roy, posted 12-06-2012 5:52 AM dayalanand roy has acknowledged this reply

  
Prev1
2
34567Next
Newer Topic | Older Topic
Jump to:


Copyright 2001-2015 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2017