Understanding through Discussion


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Author Topic:   Introduction to Genetics
NosyNed
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Posts: 8860
From: Canada
Joined: 04-04-2003
Member Rating: 4.8


Message 65 of 236 (719339)
02-13-2014 11:55 AM
Reply to: Message 64 by New Cat's Eye
02-13-2014 11:38 AM


NOT like a blueprint
Think about it like a blueprint, or a set of instructions for creating the organism.

DNA is not at all like a blueprint, not a bit. If you look at a blueprint you see no instructions for making anything at all. What you see is a picture (representation) of the result desired.

If we have to have a simple analogy DNA is a little bit like a recipe. There is generally no picture of the finished result (or at least it is not necessary to get the result). Instead there are actual instructions (add this, add that, mix, heat) and the result comes out from that.

The analogy breaks down because in the DNA there are in fact no instructions at all. There is simple a chemical pattern and a chemical environment that, when ingredients are available, the result follows from chemical reactions. In a recipe there is no need for an instruction to make CO2 to rise the bread. When the right ingredients are there it happens.


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NosyNed
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Posts: 8860
From: Canada
Joined: 04-04-2003
Member Rating: 4.8


(1)
Message 70 of 236 (719360)
02-13-2014 4:14 PM
Reply to: Message 69 by AZPaul3
02-13-2014 4:08 PM


Differences
Depending on our separate heritages there may be more difference in the genomes between you and me than between you and any specific bonobo. The important thing is where these differences occur.

You're going to have to do a lot more than assert this to convince me it's true. It seems unlikely in the extreme.


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NosyNed
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Posts: 8860
From: Canada
Joined: 04-04-2003
Member Rating: 4.8


Message 74 of 236 (719390)
02-13-2014 8:31 PM
Reply to: Message 72 by Taq
02-13-2014 5:43 PM


Us vs Them Differences
I seem to recall that many of the coding region difference between us and then are in genes known to be involved with brain development. However, I couldn't find anything on this with a quick search.
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NosyNed
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Posts: 8860
From: Canada
Joined: 04-04-2003
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Message 87 of 236 (719484)
02-14-2014 12:13 PM
Reply to: Message 83 by Taq
02-14-2014 11:00 AM


Understanding Genetics
If you want to understand genetics then you have to understand evolution. There is no way around it.

I disagree. At least to start with. As Faith has tried to do it is possible (for a time) to avoid "events", "changes" etc. and simply discuss the differences between genomes. The observations of homologs, paralogs etc. can be made without (at first) discussing how those patterns came to be.

BTW- I am learning from these discussions - thank you. I think it is moving just a bit quickly though. Are there perhaps some nice cartoon diagrams representing homologs, paralogs etc?

Of course, when one looks at the grand patterns in the genomes of a variety of critters they become awfully hard to explain (in fact are unexplainable) without concluding evolution but that can come later.


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NosyNed
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Posts: 8860
From: Canada
Joined: 04-04-2003
Member Rating: 4.8


(4)
Message 145 of 236 (719748)
02-17-2014 12:10 PM
Reply to: Message 141 by Faith
02-16-2014 6:04 PM


Clarity of Definitions
There's the Kind and then there are subspecies or variations on the Kind.

Am I correct to remember that you have agreed that, within a kind, there are populations (all of the same kind) that can not interbreed with each other? E.g., wolves and foxes of the dog kind.

As as been pointed out a number of times one biological definition of "species" is a population that breeds within itself but not outside. Thus a given wolf (e.g. maned) and a specific fox (e.g., fennec) are separate populations from a breeding point of view and therefore fit the definition of "species".

Since we all want to talk about such populations why can't we all use the word "species" instead of "subspecies", "variations", "subkind" or any other word?

It seems to me that, at that level, we are all talking about the same thing and have agreed on the existence of such populations. We certainly agree that tigers and housecats are not interbreeding populations don't we? We also agree that they originate from a population that did all interbreed, don't we? (Your view is that is the original cat kind of the arc and ours it that it goes back a little further but we otherwise agree, no?)

Based on that we all agree that the original population split into separate non-interbreeding populations. This is precisely the definition of a species.

Why not use it?


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