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Author Topic:   Not enough room in DNA
hawkes nightmare
Junior Member (Idle past 3104 days)
Posts: 28
Joined: 01-26-2010


Message 136 of 139 (557227)
04-23-2010 11:52 PM
Reply to: Message 135 by Parasomnium
04-23-2010 3:59 PM


Re: Evidence & Interpretation
clever.


I am lost, I am found. I am lost to myself, found in the darkness beneath hell itself

Only two things are infinite: the universe and human stupidity, and I'm not so sure about the former. -Albert Einstein


This message is a reply to:
 Message 135 by Parasomnium, posted 04-23-2010 3:59 PM Parasomnium has not yet responded

  
gragbarder
Junior Member (Idle past 2993 days)
Posts: 30
Joined: 03-19-2010


(1)
Message 137 of 139 (559225)
05-07-2010 5:55 PM
Reply to: Message 1 by jpatterson
04-12-2010 3:39 PM


The amount of information in the human genome is not as large as you seem to think. All of it can be compressed to only about 4MB.

quote:

“The inherent structure of genome data allows for more efficient lossless compression than can be obtained through the use of generic compression programs. We apply a series of techniques to James Watson's genome that in combination reduce it to a mere 4MB, small enough to be sent as an email attachment.”

(Human genomes as email attachments, Scott Christley, Yiming Lu, Chen Li, and Xiaohui Xie, Bioinformatics Volume 25, Number 2 Pp. 274-275)



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dennis780
Member (Idle past 2851 days)
Posts: 288
From: Alberta
Joined: 05-11-2010


Message 138 of 139 (559875)
05-11-2010 10:34 PM
Reply to: Message 6 by nwr
04-12-2010 11:58 PM


Code
You have a good topic. However, it does not present the problem for evolution that you think it poses. It is pretty well understood that the DNA is not a blueprint for the organism, but is more of a blueprint for a set of development processes out of which the organism arises.
The real implication of this is that environment plays a substantial role in forming an organism, and that DNA is only part of the story. The importance of environment has long been recognized.

nwr is correct, to some extent. However, DNA is the instructions to create life. Environment does play a part to some extent, but CODE is required for all complexities in life. You could not park your pickup in a certain environment, and given enough time, the environment would fix the transmission. This is foolish. DNA contains the set of instructions for forming, developing, and repairing the human anatomy.

Now DNA is more complex than just a set of instructions. Think of DNA as a phone book, carrying information required to complete specific task (not calling people, but you get the relationship I hope). Suppose your body requires information. There are two ways to retrieve this. One is to tear out the page of information required, and use it. The problem is, the information is no longer stored in the biological phonebook I speak of. The other way is to COPY the information, and use the duplicate to complete the task. This is what the human body does.

When specific information is required, the double-helix unwinds, and breaks in half. Cytozene, Guanine, Thymine, and Adonine fit into each of the halves, and the duplicate (mRNA) is used. The original completes, and winds back up (much like a zipper on jeans). On a side note, it`s interesting to know that the hydrogen bonds that hold DNA together are incredibly weak, and the double-helix form actually serves a much needed purpose, to strengthen it.

The duplicate is read until it reaches a stop, and the molecule encoded is produced.

None of the above described has anything to do with environment.

Now again, nwr is correct, environment does play a part in development. The body sends signals to the brain, and the brain neurons determine the correct course of action. But DNA is the one and only source of genetic information. If I had to give numbers, I would say DNA is 99% responsible for any organisms physical state, and 70-80% responsible for ones mental state. The reason for this is outside influence has a much larger effect on mental state (witnessing a murder, loss of a loved one, rape, etc.). But since DNA is responsible for the development of the brain, since fertilization, it would affect how the brain would react to any given environmental circumstances. Each human reacts to differently to similar environmental circumstances because of genetic differences.

Dennis.


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Wounded King
Member (Idle past 2170 days)
Posts: 4149
From: Edinburgh, Scotland
Joined: 04-09-2003


Message 139 of 139 (559943)
05-12-2010 5:26 AM
Reply to: Message 138 by dennis780
05-11-2010 10:34 PM


Re: Code
None of the above described has anything to do with environment.

That is only true because you left out the earlier step of how the cell knows that 'specific information is required'. This is often the result of signaling cascades initiated from the extracellular environment and can be affected by the larger environment of the organism.

Environmental effects are less obvious in humans because the womb is a very protective environment. In other organisms there are many clear examples of the effect of environmental factors, such as temperature effects on the sex of reptiles and the high sensitivity of amphibian development to salt and pH levels as well as water pollutants.

But DNA is the one and only source of genetic information.

This is obviously true because in terms of modern biology it is a tautology, what isn't true is that DNA is the only source of developmental information.

The other confounding factor is that in most larger organisms development is a highly stochastic process dependent on dynamic levels of proteins, especially those involved in signaling and transcription factors. So even with identical genetics and environment you can get a different phenotype in many instances just through chance variations during the developmental process.

I would say DNA is 99% responsible for any organisms physical state

I don't disagree with your general point about the importance of genetics but I think your 99% value is too high. Except in very controlled experimental situations the actual proportions of such things are very hard to measure.

TTFN,

WK

P.S. Just to be picky, if you are talking about mRNA then the bases are adenine, guanine, cytosine and uracil.


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