|
Register | Sign In |
|
QuickSearch
EvC Forum active members: 65 (9162 total) |
| |
popoi | |
Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/0 |
Thread ▼ Details |
|
Thread Info
|
|
|
Author | Topic: Human-Chimp DNA Difference Trebled | |||||||||||||||||||||||
blitz77 Inactive Member |
quote: Read the rest of the article here at New Scientist
|
|||||||||||||||||||||||
derwood Member (Idle past 1876 days) Posts: 1457 Joined: |
I was wondering when the creation crowd was going to try to make something of this.
Sadly, it isn't what the titles of the news articles make it out to be: "But he also found that the DNA of both species was littered with indels. His comparisons revealed that they add around another 4.0 per cent to the genetic differences." Indels - insertions and deletions - can be many hundreds of base pairs in length. Such insertions and deleteions are most likely one-time events, so phylogeneticists, for example, consider them as a single unit of change.Britten just included the base pairs of indels in his count. It really does not have the impact that the news articles' titles imply.
|
|||||||||||||||||||||||
nos482 Inactive Member |
quote: Even than it is still a high enough number to show a recent common ancestor.
|
|||||||||||||||||||||||
blitz77 Inactive Member |
Hmmm? What was I making it out to be? Anyway, it highlights what previous measurements of the difference were based on-only single based substitutions between the two.
quote: As they only compared about 0.3% of the DNA, they only glanced at the differences. Also, there are much greater differences in gene expression and other epigenetic factors.
|
|||||||||||||||||||||||
Minnemooseus Member Posts: 3941 From: Duluth, Minnesota, U.S. (West end of Lake Superior) Joined: Member Rating: 10.0 |
Wandering to the fringe of the topic:
I've wondered what the genetic differences (in a percent) between living humans. Is it a case that all living humans are 99.9999 (add even more 9's?) percent geneticly identical? Moose
|
|||||||||||||||||||||||
derwood Member (Idle past 1876 days) Posts: 1457 Joined: |
quote: Well, according to HGP data, individual humans possess an SNP about every 1200 bases (average, of course), not including indels. That means that any given human differs form any other by some 2.7 million basepairs (again, not counting indels), or 0.08%. Of course, in order to put the numbers in perspective, one would need to use Britten's technique on all taxa, and I suspect that all such comparisons would yield a similar higher degree of difference. It is all relative.
|
|||||||||||||||||||||||
derwood Member (Idle past 1876 days) Posts: 1457 Joined: |
[QUOTE]Originally posted by blitz77:
Hmmm? What was I making it out to be? Anyway, it highlights what previous measurements of the difference were based on-only single based substitutions between the two. quote: Well, even that is not really true. DNA-DNA hybvridization cannot in fact discriminate between single-base pair differences. The only way to do that is by direct DNA sequence comparisons. And when doing so, obviously, indels are taken into account.quote: Greater than what? Are not chimp genomes also expressing genes at different rates than us? It is not that WE are so much more diffeent than chimps than previously thought, it is just a new way of looking at the differences, for one thing, and the type of titles used in these articles are indicative of the anthropocentrism in not only , butin some scientists, as well. For it is THE difference which may be larger than thought, not that WE are so much different.
|
|||||||||||||||||||||||
Andya Primanda Inactive Member |
bump. Dr. Page, can you put your argument in a nutshell? The Harun Yahya committee attacked me over it and I am unable to give a definite answer to them...
http://www.harunyahya.com/70reply_andya_primanda.php
|
|||||||||||||||||||||||
derwood Member (Idle past 1876 days) Posts: 1457 Joined: |
quote: Sure: Common techniques of assessing genetic distance consider indels (insertions and deletions) to be one-time events, regardless of the size. So an insertion of a retroelement of 100 base pairs is considered a single 'difference' because the entire chunk was put in at once. Britten's technique would consider such an insertion as 100 'differences' because of the number of bps involved. I have no problem with that per se, providing we apply the technique universally, that is, apply it to all genetic distances. Doing this makes everything more geneicallt distant form everything else, so in a real sense, it makes no difference.
|
|||||||||||||||||||||||
Tranquility Base Inactive Member |
Moose
We are about 99.9% similar to each other in terms of DNA base-pairs. One in every 1000 bp will be differnt between you and your neighbour. So that's about 30 million variations across 3.1 billion bps. Only a small fraction of the genome is coding DNA (about 3%) suggesting about 1 million differneces in these regions (probably less due to preferential conservation in coding regions). The differences between individuals are 'allelic' meaning that the set of genes (at least for healthy individuals) is identical. The changes simply adjust strengths of interactions and catalyases. If your body is working then all of your tens of thousands of nanomachine types will be happily going about exactly the same jobs that they are performing in your neighbour. [This message has been edited by Tranquility Base, 10-31-2002]
|
|||||||||||||||||||||||
Andya Primanda Inactive Member |
I see. So, has anyone done that? If by this technique the human-chimp 99% dif is pushed back to 95% then every other distance would also be enlarged. Any papers on this?
|
|||||||||||||||||||||||
derwood Member (Idle past 1876 days) Posts: 1457 Joined: |
quote: I doubt it - the 'new' technique was only recently proposed. But, one can easily do such an analysis themselves - go to GENBANK and get some sequences, align them, and count away. Or go here: http://www2.norwich.edu/spage/alignmentgam.htm And do the same.
|
|||||||||||||||||||||||
Andya Primanda Inactive Member |
Dr Page, I have read the original article. (Britten 2002, PNAS). Now, I had seen that indels cannot be treated the same way as base replacements. Each base replacement equals 1 evolutionary step while each insertion/deletion event can make great differences. How do I translate the indels into evolutionary steps? By counting their average length & number?
|
|||||||||||||||||||||||
derwood Member (Idle past 1876 days) Posts: 1457 Joined: |
quote: That I do not know. I have not read Britten's paper yet, so I do not know exactly what his method it. I'm not sure what you mean by 'evolutionary steps' - is that the term Britten uses?
|
|||||||||||||||||||||||
Andya Primanda Inactive Member |
Here is the link to the PNAS article. It's free in Indonesia, anyway.
Just a moment... The NCBI entry Divergence between samples of chimpanzee and human DNA sequences is 5%, counting indels. Britten RJ. California Institute of Technology, 101 Dahlia Avenue, Corona del Mar, CA 92625. Five chimpanzee bacterial artificial chromosome (BAC) sequences (described in GenBank) have been compared with the best matching regions of the human genome sequence to assay the amount and kind of DNA divergence. The conclusion is the old saw that we share 98.5% of our DNA sequence with chimpanzee is probably in error. For this sample, a better estimate would be that 95% of the base pairs are exactly shared between chimpanzee and human DNA. In this sample of 779 kb, the divergence due to base substitution is 1.4%, and there is an additional 3.4% difference due to the presence of indels. The gaps in alignment are present in about equal amounts in the chimp and human sequences. They occur equally in repeated and nonrepeated sequences, as detected by repeatmasker (http://ftp.genome.washington.edu/RM/RepeatMasker.html). PMID: 12368483 [PubMed - in process]
|
|
|
Do Nothing Button
Copyright 2001-2023 by EvC Forum, All Rights Reserved
Version 4.2
Innovative software from Qwixotic © 2024