Genetic evolution

[pankaaj]

Why RNA has evolved as the genetic material before DNA?

[Poison]

RNA is single strand. Isn't it more possible to have a single stand first and a double strand second?

[2810712]

Availability, fitness both are important. So, even if DNA is fitter , its initial availibility may not have been adequate. We can even regard availability as a quantitative fitness and other factor is qualitative fitness.
The strand no. is also imp. but why not ssDNA be the first then??? RNA can also be double stranded, so why have DNA??? this tells that strand no. solely can't explain this as its not the sole point of differece
Seeing their complexities , lets see if we get some clue-

This example can belong one of the two possibilities


1.When evolution occurs from simple --- to complex [ U---to--T] , complex can't exists before simple. So even if complex is fitter simple has to exist first. But just existing doesn't mean being involved in life
Acoordinlgy, RNA is just reqired to be there before DNA evolves.[ this depends on how many pathways that cangive us the molecules] But it may or may not be acting as agenetic material.

2.When it comes to making a choice between two things [ U and T]with comparable complexiety, availability [besides fitness] will be an important constraint.In this case we can't say that RNA has to be there before DNA evolved.It may or may not be present.
Which one do you think the present example belongs to???


Shrei

[pankaaj]

see RNA has evovled first means that it was the first molecule to
be used as an genetic material.
I have found out following points-
1)DNA changes its physical prop. when in
a) Extreams of pH
b)Heat
c)Decrease in dielectric const. by some elements
d)Exposure to Urea, Amides etc.

Also in samples , it has been found that A & U combines quicker than T.
I'm asking why it was evolved first & not why?

[2810712]

Faster combinability [formability of RNA] is a qualitative fitness this indeed increases the availability of A-U sequence and thus affects the quantitative fitness this is how the qualitative fitness leads to natural selection.
About dielectric const and urea & amide things i think RNA will also undergo some type of changes... but only those changes would tell the relative qualitative fitnesses of the NAs.

Shrei

[Springer]

RNA is single strand. Isn't it more possible to have a single stand first and a double strand second?

How, pray tell, could one strand of RNA form without intelligent input?

[Poison]

Don't change this into "intelligent Design vs. Evolution" kind of topic too. You already have one, enjoy with it.

[Springer]

Don't change this into "intelligent Design vs. Evolution" kind of topic too. You already have one, enjoy with it.

Is that supposed to be a rational argument?

[mith]

Our goal is to keep the forum tidy and useful. That's why we don't like having two threads on the same topic.

[alextemplet]

Everything I have to say has already been said in the "Origin of Life" thread. Talk about deja vu . . .

[2810712]

Bythe way -why is RNA still a genetic material in some Viruses can be a good question then. This may be thought as convergnt evo. when only the genetic material is considered.
I mean this RNAs aren't descendants of those RNAworld RNAs. Or they might be so:shock: .
We should follow this-
I think those who believe in intelligent creation should explain the significance of this chara. [ explain why is it intelligent/best possible]
in their way and those who believe in evolution may explain their mechanism.

hrushikesh

[Poison]

Don't change this into "intelligent Design vs. Evolution" kind of topic too. You already have one, enjoy with it.

Is that supposed to be a rational argument?

I think you need a reminder: THIS IS A BIOLOGY FORUM. We already LET you to have a topic for your idea. I advise you not to push your luck...