New User? Sign Up  |  Sign In  |  Help
“Logo
 

                 LogoLogo

Question
Answer
Discover
     
Search for questions :
My Profile

philosopher

Open Questions Bookmark and Share

How. did life on Earth begin?

Discovery boosts theory that life on Earth arose from RNA-DNA mix
Newly described chemical reaction could have assembled DNA building blocks before life forms and their enzymes existed
Date:
December 28, 2020
Source:
Scripps Research Institute
Summary:
Chemists have made a discovery that supports a surprising new view of how life originated on our planet. They demonstrated that a simple compound called diamidophosphate (DAP), which was plausibly present on Earth before life arose, could have chemically knitted together tiny DNA building blocks called deoxynucleosides into strands of primordial DNA.
Share:

FULL STORY
DNA illustration (stock | Credit: © BillionPhotos.com / stock.adobe.com
DNA illustration (stock image).
Credit: © BillionPhotos.com / stock.adobe.com
Chemists at Scripps Research have made a discovery that supports a surprising new view of how life originated on our planet.

In a study published in the chemistry journal Angewandte Chemie, they demonstrated that a simple compound called diamidophosphate (DAP), which was plausibly present on Earth before life arose, could have chemically knitted together tiny DNA building blocks called deoxynucleosides into strands of primordial DNA.

The finding is the latest in a series of discoveries, over the past several years, pointing to the possibility that DNA and its close chemical cousin RNA arose together as products of similar chemical reactions, and that the first self-replicating molecules -- the first life forms on Earth -- were mixes of the two.

The discovery may also lead to new practical applications in chemistry and biology, but its main significance is that it addresses the age-old question of how life on Earth first arose. In particular, it paves the way for more extensive studies of how self-replicating DNA-RNA mixes could have evolved and spread on the primordial Earth and ultimately seeded the more mature biology of modern organisms.

"This finding is an important step toward the development of a detailed chemical model of how the first life forms originated on Earth," says study senior author Ramanarayanan Krishnamurthy, PhD, associate professor of chemistry at Scripps Research.

The finding also nudges the field of origin-of-life chemistry away from the hypothesis that has dominated it in recent decades: The "RNA World" hypothesis posits that the first replicators were RNA-based, and that DNA arose only later as a product of RNA life forms.

Is RNA too sticky?

Krishnamurthy and others have doubted the RNA World hypothesis in part because RNA molecules may simply have been too "sticky" to serve as the first self-replicators.

A strand of RNA can attract other individual RNA building blocks, which stick to it to form a sort of mirror-image strand -- each building block in the new strand binding to its complementary building block on the original, "template" strand. If the new strand can detach from the template strand, and, by the same process, start templating other new strands, then it has achieved the feat of self-replication that underlies life.

But while RNA strands may be good at templating complementary strands, they are not so good at separating from these strands. Modern organisms make enzymes that can force twinned strands of RNA -- or DNA -- to go their separate ways, thus enabling replication, but it is unclear how this could have been done in a world where enzymes didn't yet exist.

A chimeric workaround

Krishnamurthy and colleagues have shown in recent studies that "chimeric" molecular strands that are part DNA and part RNA may have been able to get around this problem, because they can template complementary strands in a less-sticky way that permits them to separate relatively easily.

The chemists also have shown in widely cited papers in the past few years that the simple ribonucleoside and deoxynucleoside building blocks, of RNA and DNA respectively, could have arisen under very similar chemical conditions on the early Earth.

Moreover, in 2017 they reported that the organic compound DAP could have played the crucial role of modifying ribonucleosides and stringing them together into the first RNA strands. The new study shows that DAP under similar conditions could have done the same for DNA.

"We found, to our surprise, that using DAP to react with deoxynucleosides works better when the deoxynucleosides are not all the same but are instead mixes of different DNA 'letters' such as A and T, or G and C, like real DNA," says first author Eddy Jiménez, PhD, a postdoctoral research associate in the Krishnamurthy lab.

"Now that we understand better how a primordial chemistry could have made the first RNAs and DNAs, we can start using it on mixes of ribonucleoside and deoxynucleoside building blocks to see what chimeric molecules are formed -- and whether they can self-replicate and evolve," Krishnamurthy says.

He notes that the work may also have broad practical applications. The artificial synthesis of DNA and RNA

22 day(s) ago

    Comment(s) (0)
    Report
   Like  
   Email to Friends  
   Bookmark  
   Subscribe to Answer Alerts  
No comments yet !     Be the first to comment !
Answers (2)

Mosin
Transpermia
Estimated flux of rocks bearing viable lifeforms exchanged between Earth and Mars.
Microbes hitching a lift between planets on rocks blasted into space by impacts. Did life originate on Mars (or Venus) and hop to the Earth billions of years ago?

http://users.tpg.com.au/users/tps-seti/transpermia.html

Posted 18 day(s) ago

( 0 )
( 0 )
    Comment(s) (0)
   Report
No comments yet ! Be the first to comment on this answer !


Kravenhead
We don't know for sure, but this is another interesting theory.
I've often wondered if there were parallel instances of evolution in different locations.
I'm sure there must have been multiple locations on Earth with near identical conditions.

It's a long shot, but it's possible some very old alien race recorded the evolution of Earth, and those records still exist somewhere.
That'd be really cool.

Posted 22 day(s) ago

( 1 )
( 0 )
    Comment(s) (0)
   Report
No comments yet ! Be the first to comment on this answer !

Edit your answer. Click save, when done.
Question Title How. did life on Earth begin?
Your Answer
  |         |                            
bold  italic  underline  strike       big  small       superscript  subscript 
  Allows to add a link.
Caption :
Link URL :
( Must starts with "http://" )
Add  |   Cancel
  Allow to insert an image. Must be among the following file types - *.jpg, *.gif, *.png & *.bmp.
Image Url :   Upload New
( Image url must always starts with " http:// " )
Width : pixels
( Must not be greater than 450px. Enter 0px for no resize )
Add  |   Cancel
  Allow to insert YouTube video. Insert the video embed code.
Embed Code :
Add  |   Cancel
Character Count ( Max. - 5000 ) : 5070
  Your comment on this question
  |         |                            
bold  italic  underline  strike       big  small       superscript  subscript 
  Allows to add a link.
Caption :
Link URL :
( Must starts with "http://" )
Add  |   Cancel
  Allow to insert an image. Must be among the following file types - *.jpg, *.gif, *.png & *.bmp.
Image Url :   Upload New
( Image url must always starts with " http:// " )
Width : pixels
( Must not be greater than 450px. Enter 0px for no resize )
Add  |   Cancel
  Allow to insert YouTube video. Insert the video embed code.
Embed Code :
Add  |   Cancel
Max Allowed : 5000 Characters Current Count : 0
  Your comment on this answer
  |         |                            
bold  italic  underline  strike       big  small       superscript  subscript 
  Allows to add a link.
Caption :
Link URL :
( Must starts with "http://" )
Add  |   Cancel
  Allow to insert an image. Must be among the following file types - *.jpg, *.gif, *.png & *.bmp.
Image Url :   Upload New
( Image url must always starts with " http:// " )
Width : pixels
( Must not be greater than 450px. Enter 0px for no resize )
Add  |   Cancel
  Allow to insert YouTube video. Insert the video embed code.
Embed Code :
Add  |   Cancel
Max Allowed : 5000 Characters Current Count : 0
Email this question link to friends
You must enter an email-address, if a name is entered and vice-versa for each friend.
Friend #1 -
Friend #2 -
Friend #3 -
Friend #4 -
Friend #5 -
Enter Security Code : *

 

Copyright ©  All rights reserved.

Contact Us   Terms of Use