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Topic: How is DNA code "executed?"  (Read 2083 times)

Offline Derek

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How is DNA code "executed?"
on: April 23, 2011, 04:09:01 AM
I got interested in this recently because of a NOVA program about growing organ's from a patient's own cells using the "scaffold" of another person's organ---with the cells melted away. The program showed a real heart beating and a real lung breathing, in a laboratory, not hooked to any living being. I was amazed.  Well it got me thinking about DNA and wondering how it is "executed." Like, when an egg cell starts splitting, each new cell must have some sort of "program counter" that knows "ok I split off from this cell, and I will eventually be part of an eyeball." or something. There's gotta be something like that...each cell must have some sort of "knowledge" as to how it is supposed to grow.  It seems like some of that knowledge must only be present when the structure of a living thing is first established---some of it is lost when it is fully grown, like for example we cannot fully regrow any part of our bodies, but other parts CAN regrow.  Interesting stuff. Anybody else read about this stuff or have interesting links to share?

Offline keyboardclass

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Re: How is DNA code "executed?"
Reply #1 on: April 23, 2011, 05:35:21 AM
More interesting stuff: On a show this week it showed animal skulls of all different shapes and sizes.  How they are produced by DNA is fascinating - a skull is formed by a number of specific bones (forget how many).  Every vertebrate has the same bones, what makes the different shaped skulls is how much time DNA gives each section to grow.  The skull is an orchestral piece!

Offline cygnusdei

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Re: How is DNA code "executed?"
Reply #2 on: April 23, 2011, 08:28:53 AM
There is a whole field that studies this kind of thing - developmental biology. In a nutshell DNA --> mRNA (transcription, heh) is well regulated that subsets of genes are expressed in varying temporal and spatial patterns.

Fly embryo is a favorite model system to study cell development:

Offline scottmcc

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Re: How is DNA code "executed?"
Reply #3 on: April 23, 2011, 11:18:51 AM
the short answer is "gene regulation."  basically, while every cell has the same exact genetic material in the chromosomes, every cell is fundamentally different in terms of which genes are allowed to be active, and to what degree.  some genes are so inactive as to be essentially absent, whereas others are constantly turned on, and everything in between is possible.  the actual chemical processes that determine this gene activity are exceptionally complex and not entirely understood.  for instance, the steroid cortisol can affect the activity of 60% of the genome, and upregulates some genes while downregulating others, all to different degrees.

just to make it more complicated, some of the things that affect dna activity are intrinsic to the cell, such as other genes, and some are messengers from other cells or the environment.  this is how cells communicate with each other on a biochemical level, as well as how they sense environmental changes.

a huge amount of research is ongoing in the field of cell-cell signalling and gene regulation.  most of the new cancer drugs in development are specifically targeted at certain genes.  a great example of this can be found here:  https://topics.nytimes.com/top/news/health/series/target_cancer/index.html?scp=2&sq=braf%20melanoma&st=cse  (series of several articles)

hopefully the above made sense.

Offline tb230

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Re: How is DNA code "executed?"
Reply #4 on: April 23, 2011, 07:48:23 PM
I liked your summary, scottmcc. You could perhaps have added that cancer (and other diseases such as diabetes and immune disorders) is caused by faulty regulation of gene activity leading to re-programming of vital cellular processes. Lack of regulation may result in overproduction or absence of certain proteins (enzymes for example) and will disturb communication processes inside and between cells. The processes controlling and regulating metabolism are particularly interesting - cancer cells have undergone metabolic reprogramming: https://www.medscape.com/viewarticle/719423

Offline thinkgreenlovepiano

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Re: How is DNA code "executed?"
Reply #5 on: April 25, 2011, 12:50:04 AM
Mmmm interesting thread. I'm studying for my biology test right now and while this doesn't exactly really help me cover test content... it's still pretty interesting :)
"A painter paints pictures on canvas. But musicians paint their pictures on silence."
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