Intelegent Life in the Sea

[lindagarrette]

I'm confused. According to this link,all radioactive mutations are hereditary.

 

http://gslc.genetics.utah.edu/units/disorders/sloozeworm/mutationbg.cfm

[TeleMad]

Lindagarrette: I'm confused. According to this link,all radioactive mutations are hereditary.

 

You're not confused....Freethinker is.

[TeleMad]

Freethinker: If the single celled organism passed along it's original DNA, rather than it's after the fact mutation, then any subsequent mutation is non hereditary.

 

Uhm, how do you think single-celled organisms typically reproduce? What do you think happens in binary fission?

[TeleMad]

Freethinker: TTBOMK, a radioactive caused mutation to a cell would not affect it's basic DNA, unless the mutation attacked the DNA itself. This should hold true to a single celled organism.

 

What in the world are you talking about?

[Tormod]

Originally posted by: TeleMad

Freethinker: If the single celled organism passed along it's original DNA, rather than it's after the fact mutation, then any subsequent mutation is non hereditary.

 

Uhm, how do you think single-celled organisms typically reproduce? What do you think happens in binary fission?

 

Ah, yes. That was what I was thinking, too. I was up way too late last night to make any sense out of this.

[Freethinker]

Originally posted by: lindagarrette

I'm confused. According to this link,all radioactive mutations are hereditary.

Please note that this page is titled:

 

"What Causes DNA Mutations?"

 

And it gives two methods. BOTH of these are based on the DNA being mutated, not just the cell itself. Not all after the fact mutations retroactively mutate the DNA.

 

Look at it on a larger scale for ease of discussion.

 

If a person is born with dna that describes two arms but thru some accident, say radioactive exposure to one arm that causes the loss of that arm. That after the fact mutation is NOT coded into their dna. Their dna will still describe two arms. Future generations wil not reflect this after the fact radiation caused mutation.

 

However if radiation effects the dna of the person so as to change the dna's desciption to "one arm", the existing individual will not LOSE an arm, but future generations will only have one.

 

Or if the dna of a cell mutates because of radiation, it might turn cancerous. This cancer will not be passed to future generations from this person.

[Freethinker]

Originally posted by: TeleMad

Uhm, how do you think single-celled organisms typically reproduce? What do you think happens in binary fission?

The method by which bacteria reproduce. The circular DNA molecule is replicated; then the cell splits into two identical cells, each containing an exact copy of the original cell's DNA. As such changes to the original cell AFTER it recieved it's ORIGINAL dna do not neccesarily retroactively change that cell's dna.

 

A cell during "binary fission" will pass along a copy of the same dna structure it originally recieved at it's source binary fission. Spontaneous mutations (as described in the site given by linda) to the *DNA* during the process would change FUTURE generations. Mutations to the internal dna of the cell would also be transmitted to future generations.

 

But I am not aware of a mechanism that would retroactively modify a cell's dna based on a mutation to other parts of the cell's structure after the fact.

 

Can you provide any factual sources that show a process which would retroactively modify a cell's dna due to after the fact mutations to the cell's structure?

[Freethinker]

Originally posted by: TeleMad

Freethinker: If the single celled organism passed along it's original DNA, rather than it's after the fact mutation, then any subsequent mutation is non hereditary.

Uhm, how do you think single-celled organisms typically reproduce? What do you think happens in binary fission?

OK, let's bring in someone that actually KNOWS what they are talking about. In order to find out what is the correct answer, I went to a friend. (compiled from his web sites) Now at the "Evolutionary Ecology Lab" SUNY-Stony Brook Dr. Missimo Pigliucci was an Associate Professor at the University of Tennessee in Knoxville, where he taught ecology and evolutionary biology. His research is on the evolution of genotype-environment interactions, i.e. on questions of nature vs. nurture. He received his Doctorate in Genetics at the University of Ferrara in Italy and his PhD in Botany from the University of Connecticut. He is now finishing a PhD in Philosophy at the University of Tennessee. He has published 72 technical papers and two books on evolutionary biology (Phenotypic Evolution, for Sinauer, with Carl Schlichting; and Phenotypic Plasticity: Beyond Nature vs. Nurture, for Johns Hopkins University Press). He has recently completed an edited book entitled The Evolution of Complex Phenotypes soon to be published by Oxford University Press (with Katherine Preston). Dr. Pigliucci has been awarded several times the Oak Ridge National Labs award for excellence in research and has won the prestigious Dobzhansky Prize from the Society for the Study of Evolution, of which he is now Vice President.

 

Seems he might know something about this. I asked him specifically:

 

>>Massimo. Hope things are going well for you with your move.

(blah blah blah personal stuff)

>>I was wondering if you could help provide an answer for a discussion I am

>>involved with....

(blah blah blah)

>>Relative to single cell mutations. Binary fission. We are agreed on any

>>changes to the cell's dna being passed generationally. But what of

>>retroactive mutation of dna? If an existing cell with a given dna

>>structure mutates, say from radiation, not a change to the dna itself, but

>>to some other part of the cell, does that cause a change to that cell's

>>dna?

(blah blah blah... more details and friendly chatter)

 

His answer

On 9/21/2004 at 1:28 PM Massimo Pigliucci (eddress removed) wrote:

 

>Glenn,

>

>the simple answer to your question is no. There is no known mechanism by

>which environmentally-induced changes can influence the structure of DNA

>in a backwards fashion, therefore Lamarckian evolution is impossible

>(except in the case of cultural evolution, of course).

(friendly chatter removed)

>Cheers,

>Massimo

 

Like I said many times here already, Lamarckian evolution does not work.

 

Now does anyone else want to argue it further?

[Tormod]

Okay, good work. But I'm confused. I was thinking that radiation could cause changes to the DNA, and that this would cause the change to be passed on. Your friend comments on changes to everything BUT the DNA. Can you help me understand why radiation cannot change the DNA?

[Freethinker]

Originally posted by: Tormod

Okay, good work. But I'm confused. I was thinking that radiation could cause changes to the DNA, and that this would cause the change to be passed on.

Your only confused about what the discussion was. Not what you know to be true. At least half of it.

 

I never argued about whether radiation could cause a mutation in dna. What I showed to be false was that ALL mutations to a single celled organism are passed genetically. Or even that MOST would. Unc had asked:

Originally posted by: Uncle Martin

I'm curious,.... is radiation a factor in mutations that lead to evolution?

Which was answered with:

Originally posted by: TeleMad

We, and everything else living on the surface, are subjected to this radiation everyday of our lives and it is one factor that helps evolution by mutation/selection occur.

One factor, yes. But not a major one because most mutation caused by radiation is not to the dna, but to individual body cells. Thus it would not affect it's dna and would not be passed genetically. I specifically stated:

Originally posted by: Freethinker

The problem with asserting radiation as a source of evolutionary mutation is that most radiation mutation is not genetically hereditary. Lamarckian Evolution doesn't work.

 

In fact it would seem that conventional radioactive sources would typically generate non-hereditary mutations.

My comment was correct from the beginning. But no one seemed to understand it. So I brought in an outside reference to settle it.

 

So yes you are correct that

radiation could cause changes to the DNA, and that this would cause the change to be passed on

but the significantly greater amount of mutations to cells, especially radiation based, is NOT genetically passed.

[TeleMad]

FreeThinker: And it gives two methods. BOTH of these are based on the DNA being mutated, not just the cell itself. Not all after the fact mutations retroactively mutate the DNA.

 

You don’t even know what a mutation is! No wonder you’re all confused. Don’t worry, I’ll explain it to you a bit in the rest of my reply.

 

FreeThinker: If a person is born with dna that describes two arms but thru some accident, say radioactive exposure to one arm that causes the loss of that arm. That after the fact mutation is NOT coded into their dna. Their dna will still describe two arms. Future generations wil not reflect this after the fact radiation caused mutation.

 

Goodness gracious, where to start!

 

First, we have to move away from FT’s overactive imagination and come back to something a bit more realistic: we’ll leave arms falling off due to exposure to radiation behind. Something that actually does happen frequently is that skin cells die and peel off after exposure to the sun (sufficient to cause sunburn, of course). Why does the skin peel off? Because a ‘boat load’ of cells were killed by the radiation. How? Their DNA was mutated to such an extent that they couldn’t completely repair the damage…and they died.

 

Okay, so what about something that we can reasonably expect to actually lead to loss of an arm, such as being in a bad car accident? Yes, the arm would have ‘fallen off’ and, yes the DNA would not have been altered.. But losing an arm in that manner is NOT a mutation (why do I get the feeling that FT will now try to change context – leaving evolution, genetics, and biology behind - and stretch terms to their extreme try to save face?).

 

Don’t worry, I’ll explain a bit more to you just below.

 

FreeThinker: However if radiation effects the dna of the person so as to change the dna's desciption to "one arm", the existing individual will not LOSE an arm, but future generations will only have one.

 

You don’t deserve your new pic…DNA double helix. :-)

 

What you said above just doesn’t hold up. For example, if the DNA in someone’s toe was changed to say “one arm”, then future generations would still have two arms. Here’s the deal FT.

 

Humans basically have two types of cells: somatic cells and germ-line cells (such as gametes). Somatic cells are body cells – muscle fibers, neurons, epithelial cells lining the small intestine, skin cells, and so on. Gametes are the sex cells. Sexual reproduction involves the male haploid gamete and a female haploid gamete fusing to form a diploid zygote. Assuming all goes well, the zygote then goes on to become an embryo, then a fetus, and eventually, an adult. It is only the germ-line cells that can potentially pass on their genetic information to the next generation. So the rule is: mutations in gametes can be passed on; mutations in somatic cells can’t.

 

Now, what is a mutation? In biology, a mutation is a change in a cell’s DNA. Sometimes the meaning is restricted to changes that are transmitted from one generation to the next, and sometimes that restriction is not applied (i.e., the change could occur in an epithelial cell lining your small intestine and it would still be a mutation). Another meaning in biology is the phenotype generated by the change in DNA. Regardless which of these meanings applies in a given context, a mutation is associated with a change in DNA. Getting an arm cutoff by a saw is NOT a mutation: it’s an injury.

[TeleMad]

FreeThinker: The method by which bacteria reproduce. The circular DNA molecule is replicated; then the cell splits into two identical cells, each containing an exact copy of the original cell's DNA. As such changes to the original cell AFTER it recieved it's ORIGINAL dna do not neccesarily retroactively change that cell's dna.

 

Too bad that’s not what anyone – except you, who doesn’t know what you are talking about – is talking about.

 

We are talking about MUTATIONS – changes to a cell’s DNA. We are NOT talking about a mere physical change to a cell that doesn’t alter the DNA.

 

If a mutation occurs in a bacterial genome, then either one or both strands will have some change in its sequence. When the DNA is replicated in preparation for cell division, either one of both of the new cells can inherit the mutation. Consider this:

 

Original DNA

AT

CG

GC

TA

 

Spontaneous mutation occurs in one strand

AT

CG

GU (cytosine is deaminated, converting it into uracil)

TA

 

DNA is replicated (the mutation wasn’t repaired in time)

AT AT

CG CG

GC AU

TA TA

 

Now one cell will end up with the original DNA sequence, and the other will end up with the mutation.

 

 

FreeThinker: A cell during "binary fission" will pass along a copy of the same dna structure it originally recieved at it's source binary fission.

 

Not if any of several kinds of spontaneous mutation occurred in the interim. See just above.

 

FreeThinker: But I am not aware of a mechanism that would retroactively modify a cell's dna based on a mutation to other parts of the cell's structure after the fact.

 

And you’re the only that thinks that’s the topic of discussion!

 

FreeThinker: an you provide any factual sources that show a process which would retroactively modify a cell's dna due to after the fact mutations to the cell's structure?

 

Don’t need to because that is not at all what I’ve been saying. You’re lost in your own little world Wake up and pay attention.

[TeleMad]

FreeThinker: OK, let's bring in someone that actually KNOWS what they are talking about.

 

I’m already here.

 

FreeThinker:

 

>>Massimo. Hope things are going well for you with your move.

(blah blah blah personal stuff)

>>I was wondering if you could help provide an answer for a discussion I am

>>involved with....

(blah blah blah)

>>Relative to single cell mutations. Binary fission. We are agreed on any

>>changes to the cell's dna being passed generationally. But what of

>>retroactive mutation of dna? If an existing cell with a given dna

>>structure mutates, say from radiation, not a change to the dna itself, but

>>to some other part of the cell, does that cause a change to that cell's

>>dna?

(blah blah blah... more details and friendly chatter)

 

His answer

On 9/21/2004 at 1:28 PM Massimo Pigliucci (eddress removed) wrote:

 

>Glenn,

>

>the simple answer to your question is no. There is no known mechanism by

>which environmentally-induced changes can influence the structure of DNA

>in a backwards fashion, therefore Lamarckian evolution is impossible

>(except in the case of cultural evolution, of course).

(friendly chatter removed)

>Cheers,

>Massimo

 

Beautiful! You’ve just shown us that he says YOUR STRAWMAN is wrong! Good work.

 

Now, when do you plan on dealing with the ACTUAL topic of mutation? Hint: we're not offering or discussing Lamarckian evolution: that's YOU stuffing a bogus position into our mouths.

 

 

PS: Tell you what. Why not send your friend my last 3 posts in this thread and see if he is on my side - the correct, biological side - or on your side, which is based on a gross misconception about what a mutation is.

[Tim_Lou]

Originally posted by: Freethinker

If the single celled organism passed along it's original DNA, rather than it's after the fact mutation, then any subsequent mutation is non hereditary. Lamarckian Evolution doesn't work.

 

 

but mutation in germs cells or eggs cells in the body does work!

 

edit: damn, as i read through the huge amount of posts posted in such a short time, i figured out that my idea has been posted by TeleMad.......

[TeleMad]

FreeThinker: Unc had asked:

 

--------------------------------------------------------------------------------

Originally posted by: Uncle Martin

I'm curious,.... is radiation a factor in mutations that lead to evolution?

--------------------------------------------------------------------------------

 

Which was answered with:

 

 

--------------------------------------------------------------------------------

Originally posted by: TeleMad

Background radiation - radation produced from the radioactive decay of elements found right here in the Earth's crust - is one factor responsible for spontaneous mutations in organisms. We, and everything else living on the surface, are subjected to this radiation everyday of our lives and it is one factor that helps evolution by mutation/selection occur.

--------------------------------------------------------------------------------

 

One factor, yes.

 

Just as I said…twice.

 

FreeThinker: But not a major one …

 

And I didn’t say it otherwise.

 

FreeThinker: … because most mutation caused by radiation is not to the dna,

 

WRONG! ‘All’ mutation caused by radiation is to the DNA.

 

FreeThinker: I specifically stated:

 

--------------------------------------------------------------------------------

Originally posted by: Freethinker

The problem with asserting radiation as a source of evolutionary mutation is that most radiation mutation is not genetically hereditary. Lamarckian Evolution doesn't work.

 

In fact it would seem that conventional radioactive sources would typically generate non-hereditary mutations.

--------------------------------------------------------------------------------

 

My comment was correct from the beginning. But no one seemed to understand it.

 

LOL! You don’t even know why that can be considered correct!

 

In a human, the vast majority of volume consists of somatic cells – not gametes. So it is true that most mutations generated by radiation would not be passed on to offspring.

 

However, for bacteria, all their (nucleoid) DNA is passed on, to one cell or the other (see my explanatory example a few posts above). So any change to the DNA affects at least one of the cells that results from reproduction, and possibly both.

 

FreeThinker: So I brought in an outside reference to settle it.

 

And that he did…he settled that matter….YOUR STRAWMAN – you know, the bogus position you keep trying to stuff into my mouth - is busted.

 

FreeThinker: but the significantly greater amount of mutations to cells, especially radiation based, is NOT genetically passed.

 

That's wrong when talking about bacteria.

[TeleMad]

Just to completely squash FreeThinker (as if I haven't already), I whipped out the old college books and looked up "mutation" in the glossaries and the defining statements in the text.

 

Emphasis is in the original in all cases.

 

”In its broadest sense, the term mutation refers to any change in the sequence of nucleotides in a genome.” (The World of the Cell: Third Edition, Wayne M. Becker, Jane B. Reece, & Martin F. Poenie, Benjamin/Cummings, 1996, p584)

 

”Some spontaneous changes to DNA are actually desirable because such changes, called mutations, provide the genetic variability that is the raw material of evolution.” (The World of the Cell: Third Edition, Wayne M. Becker, Jane B. Reece, & Martin F. Poenie, Benjamin/Cummings, 1996, p470)

 

”Mutation A sudden inheritable change in the phenotype of an organism.” (Biology of Microorganisms: Sixth Edition, Thomas D. Brock & Michael T. Madigan, Prentice Hall, 1991, p841)

 

”Mutation is the inherited change in the base sequence of the nucleic acid comprising the genome of an organism.” (Biology of Microorganisms: Sixth Edition, Thomas D. Brock & Michael T. Madigan, Prentice Hall, 1991, p235)

 

”As previously mentioned, a Mutation is a heritable change in the base sequence of the DNA of an organism. (Biology of Microorganisms: Sixth Edition, Thomas D. Brock & Michael T. Madigan, Prentice Hall, 1991, p235)

 

”As previously mentioned, mutations arise because of changes in the base sequence in the DNA.” (Biology of Microorganisms: Sixth Edition, Thomas D. Brock & Michael T. Madigan, Prentice Hall, 1991, p238)

 

”mutation In genetics, a permanent, heritable change in the nucleotide sequence of a chromosome, usually in a single gene; commonly leads to change in or loss of normal function of the gene product.” (Molecular Cell Biology: Fourth Edition, Harvey Lodish, Arnold Berk, S. Lawrence Zipursky, Paul Matsudaira, David Baltimore, and James Darnell, W. H. Freeman & Co., 2000, Glossary G-12)

 

”Such changes in DNA sequence, called mutations, can lead to loss of the encoded protein or to a change in its structure.” (Molecular Cell Biology: Fourth Edition, Harvey Lodish, Arnold Berk, S. Lawrence Zipursky, Paul Matsudaira, David Baltimore, and James Darnell, W. H. Freeman & Co., 2000, p254)

 

”mutation The process that produces an alteration in DNA or chromosome structure; the source of most alleles.” (Concepts of Genetics: Fifth Edition, William S. Klug & Michael R. Cummings, Prentice Hall, 1997, Appendix B B-12)

 

”What are the sources of genetic variation?

Classically, there are two sources of genetic variation: chromosomal mutations and gene mutations. The former, also called chromosomal aberrations, includes duplication, deletion, or rearrangement of chromosome segments. Gene mutations result from a change in the stored chemical information in DNA, collectively referred to as an organism’s genotype.” (Concepts of Genetics: Fifth Edition, William S. Klug & Michael R. Cummings, Prentice Hall, 1997, p8)

 

”mutation: A change in the nucleotide sequence of the DNA in a cell.” (Fundamentals of Anatomy & Physiology: Fourth Edition, Frederic H. Martini, Prentice Hall, 1998, Glossary G-21)

 

”MUTATIONS Mutations are permanent alterations in a cell’s DNA that affect the nucleotide sequence of one or more genes.” (Fundamentals of Anatomy & Physiology: Fourth Edition, Frederic H.

[Tormod]

Originally posted by: TeleMad

Just to completely squash FreeThinker (as if I haven't already).

 

Tele, Please check your Private messages before you post anything else along this line.