Can the DNA of a parent and child be distinguished.

Discussions on introductory science topics. Ask simple or beginner questions and expect clear and level answers.

Can the DNA of a parent and child be distinguished.

Postby A_Seagull on May 29th, 2017, 5:44 pm 

Just a simple question really, but one that might have implications for the understanding of evolution...

Suppose you have the DNA of a parent and a child, and clearly they can be unambiguously be identified as parent and child, but can it be distinguished which is the parent and which is the chid?

Your responses would be appreciated.
User avatar
A_Seagull
Forum Neophyte
 
Posts: 14
Joined: 29 Apr 2017
eagle liked this post


Re: Can the DNA of a parent and child be distinguished.

Postby SciameriKen on May 29th, 2017, 9:57 pm 

Barring "close" family relations - only one set of DNA should share commonality with the other parent. Aside from that the parent DNA may show signs of aging (greater methylation). Maybe someone here knows something other telltale signs.
User avatar
SciameriKen
Forum Moderator
 
Posts: 1266
Joined: 30 Aug 2005
Location: Buffalo, NY


Re: Can the DNA of a parent and child be distinguished.

Postby BioWizard on May 30th, 2017, 7:17 am 

Maybe cross over events can be telltale? Though they're probably not foolproof if you only have the DNA of parent and child, and no other relatives.

What about telomere length?
User avatar
BioWizard
Forum Administrator
 
Posts: 12691
Joined: 24 Mar 2005
Location: United States
Blog: View Blog (3)
eagleSciameriKen liked this post


Re: Can the DNA of a parent and child be distinguished.

Postby Braininvat on May 30th, 2017, 9:44 am 

What are the "implications for the understanding of evolution" alluded to in the OP?

Is the mitochondrial DNA also part of the sample set? If one nuclear DNA sample happens to be XX, and the other is XY, and the mitochondrial DNA is the same for each, then you would in that case know that XX sample is the mom. If the mito DNAs are a different, then XY is a father to XX daughter. However, if both are XX, then the mitos will perforce be the same, and therefore ambiguous, so you might use telomere length as Bio said. If both are XY, then mitos will perforce be different, and again you need telomeres or other method.
User avatar
Braininvat
Resident Member
 
Posts: 5842
Joined: 21 Jan 2014
Location: Black Hills
eagleBioWizard liked this post


Re: Can the DNA of a parent and child be distinguished.

Postby A_Seagull on May 30th, 2017, 5:47 pm 

Braininvat » May 31st, 2017, 1:44 am wrote:What are the "implications for the understanding of evolution" alluded to in the OP?



I was just thinking that if it was impossible to distinguish between the DNA of a parent and child that, so far as the DNA was concerned, evolution would be time symmetric.. no difference between forward and back. What implications that might have, I don't know.

But in any case the answers in this thread have shown that it is possible to distinguish between parent and child, so the time symmetry vanishes.
User avatar
A_Seagull
Forum Neophyte
 
Posts: 14
Joined: 29 Apr 2017
eagleSciameriKen liked this post


Re: Can the DNA of a parent and child be distinguished.

Postby eagle on June 2nd, 2017, 8:53 am 

I was going to post but all y'all already beat me to the punch and with more detail.

WRT counterfactual time-symmetric evolution, that would imply no evolution, and thus doesn't hold, as we observe.
eagle
Forum Neophyte
 
Posts: 19
Joined: 04 May 2017


Re: Can the DNA of a parent and child be distinguished.

Postby A_Seagull on June 2nd, 2017, 6:10 pm 

eagle » June 3rd, 2017, 12:53 am wrote:I was going to post but all y'all already beat me to the punch and with more detail.

WRT counterfactual time-symmetric evolution, that would imply no evolution, and thus doesn't hold, as we observe.


Not necessarily. A drunken random walk is essentially time symmetric, yet over time the person strays further away from the origin.
User avatar
A_Seagull
Forum Neophyte
 
Posts: 14
Joined: 29 Apr 2017
BioWizardeagle liked this post


Re: Can the DNA of a parent and child be distinguished.

Postby eagle on June 2nd, 2017, 7:16 pm 

I'm not sure whether that counts as evolution. :) Let's say that two different types of bacteria become randomly farther apart, that seems like variation without selection. Maybe it's just a question of semantics, but I could at least see a reasonable case for not calling that evolving.
eagle
Forum Neophyte
 
Posts: 19
Joined: 04 May 2017
BioWizard liked this post


Re: Can the DNA of a parent and child be distinguished.

Postby BioWizard on November 25th, 2017, 3:06 pm 

eagle, A_Seagull,

I think in the absence of all other context, it might be difficult to tell, just from two sets of DNA, which DNA belongs to parent and which belongs to child. Any changes to the DNA could have happened in either direction, and therefor cannot by themselves provide time orientation.

While it may never become possible to accurately guess the age of an individual from their genome, it may be possible to at least place the genomes of parent and child with respect to one another. And the wider the age gap the easier it'll be. Of course this could be thrown off by certain conditions, for example progeria.

Regarding evolutionary implications, I would say that similarly there, comparing the genomes of any two species is not enough to derive relative relationships. You need to bring it additional evidence, possibly including DNA data from other related species, along with historical data, to paint a picture of the possible evolutionary course that connects one specie to the other.
User avatar
BioWizard
Forum Administrator
 
Posts: 12691
Joined: 24 Mar 2005
Location: United States
Blog: View Blog (3)


Re: Can the DNA of a parent and child be distinguished.

Postby wolfhnd on November 25th, 2017, 10:59 pm 

It may be possible by analysis of epigenetic markers but would require more than one set of DNA samples from gametes and other cells. I'm not at all sure if this is possible but perhaps Bio will consider it and enlighten us.
User avatar
wolfhnd
Resident Member
 
Posts: 4342
Joined: 21 Jun 2005
Blog: View Blog (3)


Re: Can the DNA of a parent and child be distinguished.

Postby BioWizard on November 25th, 2017, 11:46 pm 

wolfhnd » 25 Nov 2017 09:59 pm wrote:It may be possible by analysis of epigenetic markers but would require more than one set of DNA samples from gametes and other cells. I'm not at all sure if this is possible but perhaps Bio will consider it and enlighten us.


That’s right. The cellular source of DNA is a major factor here. For example if the parent DNA comes from a gamete cell and the offspring DNA comes from a skin cell, we might be fooled into thinking the gamete DNA donor is actually younger. Not sure how to say this other than that this is not yet an exact science, as far as I know. But then again I don’t work in forensics.
User avatar
BioWizard
Forum Administrator
 
Posts: 12691
Joined: 24 Mar 2005
Location: United States
Blog: View Blog (3)


Re: Can the DNA of a parent and child be distinguished.

Postby BioWizard on November 25th, 2017, 11:50 pm 

Point remains, however, that being presented by two sets of DNA data is not going to be enough. You need a bunch of additional and meta data to be able to put things in context. There’s no DNA equivalent to the rings on a tree’s trunk. It’s all highly contextual.
User avatar
BioWizard
Forum Administrator
 
Posts: 12691
Joined: 24 Mar 2005
Location: United States
Blog: View Blog (3)


Re: Can the DNA of a parent and child be distinguished.

Postby wolfhnd on November 26th, 2017, 2:49 am 

DNA sequencing is a complicated process and determining a match is much simpler than say creating a complete genomic analysis.

That doesn't mean the OP is not interesting. DNA can be thought of as information. It isn't clear if information doesn't defy what we think are the normal physical restraints of matter. That is if matter and information are not the same thing. In any case we think energy is released when information is erased.

http://physicsworld.com/cws/article/new ... you-energy

Information certainly seems to also reduce entropy. When we die the information in our cells becomes disorganized so death could be seen as information losing the battle against entropy. The natural process of decay while we are alive is forestalled so it could be said that time has been slower. This may or not be rational /:-)
User avatar
wolfhnd
Resident Member
 
Posts: 4342
Joined: 21 Jun 2005
Blog: View Blog (3)


Re: Can the DNA of a parent and child be distinguished.

Postby BioWizard on November 26th, 2017, 11:51 am 

wolfhnd » 26 Nov 2017 01:49 am wrote:DNA sequencing is a complicated process and determining a match is much simpler than say creating a complete genomic analysis.

That doesn't mean the OP is not interesting. DNA can be thought of as information. It isn't clear if information doesn't defy what we think are the normal physical restraints of matter. That is if matter and information are not the same thing. In any case we think energy is released when information is erased.

http://physicsworld.com/cws/article/new ... you-energy


DNA is information. I didn't that was the question here, though. I believe the question is just how much relational knowledge can one reconstruct from just two sets of DNA, one set from parent and one set from child.

I can give you a screw from my car's engine and ask you to guess the age of my car. You can look at the screw and see that it looks brand new and guess that my car is new. But I could've just had that screw replaced last week, and without that contextual information, any conclusion you derive based on the screw in isolation would be as good as a random guess.

Without proper context, DNA information could be as helpful as it could be misleading.

Information certainly seems to also reduce entropy. When we die the information in our cells becomes disorganized so death could be seen as information losing the battle against entropy.


I thought information is by "definition" the reduction of entropy? I could be wrong.

The natural process of decay while we are alive is forestalled so it could be said that time has been slower. This may or not be rational /:-)


Say what now? :]
User avatar
BioWizard
Forum Administrator
 
Posts: 12691
Joined: 24 Mar 2005
Location: United States
Blog: View Blog (3)



Return to Beginner Science

Who is online

Users browsing this forum: No registered users and 3 guests