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Author Topic:   Can mutation and selection increase information?
Taq
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Posts: 8519
Joined: 03-06-2009


(1)
Message 133 of 222 (816737)
08-10-2017 10:37 AM
Reply to: Message 129 by CRR
08-10-2017 2:17 AM


Re: random and non-random mutations
CRR writes:

I believe (my opinion) the answers are maybe and yes.

I suspect that if a part of the genome is targeted for hypermutation then the ratio could change, but I have no other evidence to support or refute that hypothesis at this time.

I think you know that we need more than "I suspect" and "I believe".

CRR writes:

Which would I think make it a goal directed random search.

That would be an oxymoron. If it is a random search then it is not goal directed. Goal directed means making specific mutations to a specific gene with a known specific outcome.

Edited by Taq, : No reason given.


This message is a reply to:
 Message 129 by CRR, posted 08-10-2017 2:17 AM CRR has replied

Replies to this message:
 Message 136 by CRR, posted 08-11-2017 6:03 PM Taq has replied

  
Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 138 of 222 (816828)
08-11-2017 6:15 PM
Reply to: Message 136 by CRR
08-11-2017 6:03 PM


Re: random and non-random mutations
CRR writes:

You can have a search that is goal directed but can be random, systematic, or guided.

No, you can't. Words mean things. In biology, a goal directed mutation is one that is non-random. It is a specific change to a specific base in a specific gene that results in a specific outcome. That is what "goal directed" means in biology. A random mutation is just the opposite.

Now consider the bacteria responding to an environmental stress. It begins to hypermutate certain regions of the genome in order to adapt. The goal is to adapt to the stress; although I don't suggest the bacteria has a conscious intention to to do this. The search space is restricted to certain parts of the genome. Within this space we assume the search is blind and random.

Those are random mutations, not goal directed mutations. Increasing the random mutation rate is an increase in random mutations. Those mutations will include beneficial, neutral, and deleterious mutations. Increasing the rate at which a random number generator operates does not turn it into a non-random number generator.


This message is a reply to:
 Message 136 by CRR, posted 08-11-2017 6:03 PM CRR has replied

Replies to this message:
 Message 139 by CRR, posted 08-13-2017 2:01 AM Taq has replied

  
Taq
Member
Posts: 8519
Joined: 03-06-2009


(1)
Message 144 of 222 (816972)
08-14-2017 11:08 AM
Reply to: Message 139 by CRR
08-13-2017 2:01 AM


Re: random and non-random mutations
CRR writes:

Perhaps it does but I couldn't find it in a glossary of biological terms.
Perhaps you could supply a link to a suitable definition.

If you are using them to mean the very same thing, then just use the term "random mutations".

However I think you might be confusing "goal directed search" with a "guided search". In fact if the organism can go to a specific base in a specific gene to get a specific outcome it's not a search at all.

If mutations are produced without any meaningful connection to what would help or hurt the organism, then it is random with respect to fitness.

Another example is the immune system. In response to an infection the immune system starts producing many variations looking for an antibody for the invader. This is goal directed but the immune system can't go directly to the specific mutation that will produce the antibody and it might have to use a blind search to find an antibody that works. (Not a perfect analogy since the immune system starts with a library of antibodies that have worked for past infections.)

Those are random mutations. It is not goal directed mutagenesis.


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Taq
Member
Posts: 8519
Joined: 03-06-2009


(1)
Message 145 of 222 (816973)
08-14-2017 11:09 AM
Reply to: Message 141 by CRR
08-13-2017 7:21 PM


Re: random and non-random mutations
CRR writes:

goal–directed: aimed toward a goal or toward completion of a task.
As I have explained a search can have a goal while still being a blind search, as opposed to a guided search. And a blind search can be a random search.
(Maybe I should be writing "goal-directed" rather than "goal directed".)

There is already a term that describes this process. It is called random mutagenesis.

All you are doing is redefining terms to make them sound more guided when they aren't.


This message is a reply to:
 Message 141 by CRR, posted 08-13-2017 7:21 PM CRR has replied

Replies to this message:
 Message 147 by CRR, posted 08-16-2017 6:51 PM Taq has replied

  
Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 152 of 222 (817400)
08-17-2017 11:15 AM
Reply to: Message 147 by CRR
08-16-2017 6:51 PM


Re: random and non-random mutations
CRR writes:

I have already made the distinction between a goal-directed search and a guided search.

All you have is a semantic argument, as usual.

A search can be goal-directed and unguided, completely random, at the same time.

What would it look like if random mutations were not goal directed? How would they differ from goal directed random mutations?

Rather than "redefining terms" I am using already established terms in their normal way.

Can you show us a single peer reviewed paper that uses those terms in those ways?


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Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 162 of 222 (818080)
08-23-2017 11:43 AM
Reply to: Message 156 by CRR
08-21-2017 4:37 AM


Re: random and non-random mutations
CRR writes:

I have a copy of Origin of Species which contains information.
I buy another copy. Do I now have twice as much information? Or 2 copies of the same information?

How does that apply to biology?

Can a gene duplication change phenotype? If yes, does that count as an increase in information by your definition?


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Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 163 of 222 (818082)
08-23-2017 11:45 AM
Reply to: Message 159 by CRR
08-22-2017 2:44 AM


Re: random and non-random mutations
CRR writes:

No, he just uses a different definition of information than Shannon; must people do. Shannon's definition is very restrictive but suited for the purpose for which he was using it.

But is that definition applicable to biology?

Random mutation degrades existing information. Take a page from a book and start randomly mutating the letters and pretty soon it is unreadable and any information on that page is lost.

Then you would define every difference between the chimp and human genomes as a loss in information. In other words, your definition is not relevant to biology and evolution since evolution can proceed without needing to gain information as you define it.


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Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 174 of 222 (818244)
08-25-2017 11:04 AM
Reply to: Message 169 by CRR
08-25-2017 1:49 AM


Re: Measuring Information
CRR writes:

Note that the authors highlight the distinction between functional information and Shannon information.

So if a mutation changes what the protein binds to, would that be an increase in information?


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Taq
Member
Posts: 8519
Joined: 03-06-2009


(2)
Message 175 of 222 (818245)
08-25-2017 11:07 AM
Reply to: Message 170 by CRR
08-25-2017 2:09 AM


Re: random and non-random mutations
CRR writes:

We already know that most evolution happens by the loss of information.

Then why do you keep saying that there has to be an increase in information in order for macroevolution to occur? It would seem that evolution does just fine without needing to meet the requirements you have set for it.

To use an analogy, you are saying that a baseball player has to hit a ball 2,000 feet in order to get a home run. All the while, baseball players are hitting balls 400 feet and getting home runs. You have lost touch with reality.


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Taq
Member
Posts: 8519
Joined: 03-06-2009


(1)
Message 191 of 222 (818424)
08-28-2017 11:18 AM
Reply to: Message 184 by Porkncheese
08-27-2017 8:59 AM


Porkncheese writes:

Has a cell ever been observed to create a totally different cell?

There are no two cells on Earth that are totally different from one another. Even human cells and bacterial cells share features.

Seeing that would have been required to produce such different types of life forms.

Evolution does cause descendants to be modified versions of their ancestors. How is that a problem?

Edited by Taq, : No reason given.


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Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 192 of 222 (818425)
08-28-2017 11:20 AM
Reply to: Message 188 by Porkncheese
08-27-2017 10:01 AM


Re: Cells
Porkncheese writes:

From what I understand a cell can only multiply itself.

You started out as a single cell, and now you have all these different types of cells in your body. How do you think that happened?


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Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 197 of 222 (818559)
08-30-2017 10:56 AM
Reply to: Message 193 by CRR
08-30-2017 12:22 AM


Re: Cells
CRR writes:

However in this case the original cell has ALL of the genetic and extra-genetic information for EVERY cell including the information to switch off the un-needed functions in each specialist tissue. That is the difference between a complex organism and a single celled organism.

I would agree that the production of tissues is what separates complex eukaryotes (animals, plants) from less complex species (protists, prokaryotes). It comes down to the evolution of switches in the genome that respond to chemicals released by neighboring cells. It is interesting to note that complex animals share some of the more important switches which are called homeobox genes.


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Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 202 of 222 (818622)
08-31-2017 10:38 AM
Reply to: Message 198 by CRR
08-30-2017 6:15 PM


Re: Cells
CRR writes:

My conclusion is that size is not a good measure of information content. I have found that with books. You can't determine the value of the content by weighing a book or by doing a word count.

If you found the following sequence in a book, would you think that it contained information?

MGDVEKGKKIFIMKCSQCHTVEKGGKHKTGPNLHGLFGRKTGQAPGYSYTAANKNKGIIW
GEDTLMEYLENPKKYIPGTKMIFVGIKKKEERADLIAYLKKATNE


This message is a reply to:
 Message 198 by CRR, posted 08-30-2017 6:15 PM CRR has replied

Replies to this message:
 Message 203 by jar, posted 08-31-2017 11:09 AM Taq has taken no action
 Message 209 by CRR, posted 08-31-2017 7:26 PM Taq has replied

  
Taq
Member
Posts: 8519
Joined: 03-06-2009


Message 210 of 222 (818669)
08-31-2017 8:00 PM
Reply to: Message 209 by CRR
08-31-2017 7:26 PM


Re: Cells
A simple answer to my question would be most appreciated.

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Taq
Member
Posts: 8519
Joined: 03-06-2009


(5)
Message 216 of 222 (818717)
09-01-2017 11:03 AM
Reply to: Message 211 by CRR
08-31-2017 8:25 PM


Re: Information
CRR writes:

We could look it up in a dictionary and get some information. We can read a recipe and get more information. We can taste it and get more information. We now know what it is, how to make it, and what it tastes like. We know that we have acquired and increased information; we can qualitatively say we have more information even if we can't quantitatively say how much.

The problem is that none of this is relevant to biology. The cell doesn't read DNA like a recipe in order to make proteins. DNA isn't an abstract written language like human languages. DNA contains physical information like all other molecules. DNA contains the information for a cell in the same way that oxygen and hydrogen contain the information for water.


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