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Topic: Genetically modified foods  (Read 7470 times)

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laxbaby711

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Genetically modified foods
« on: May 10, 2005, 07:26:19 PM »
How are Genetically modified foods related to chemistry? what is the chemistry behind it? Please hep. thank you

Offline constant thinker

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Re:Genetically modified foods
« Reply #1 on: May 10, 2005, 08:20:09 PM »
I'm far from an expert, but from what I know GE (gentically engineered) foods aren't always directly related to chemistry. Sometimes it is only cross breeding or picking your best plants which requires no modification of the plants DNA directly. Other times though scientists go into the the DNA of a plant equivalant of the stem cell, and they change which genes are "on or off". They can turn on/off, take out, or plug different genes for different purposes. This is wear the chemistry comes into play. Examples include but not limited to: resistance to drought, insects, disease, large yields of food, faster growth, slower growth, increased overall size, etc.

The biggest misconception of GE is that they are always modifying the DNA in labs. As I previously stated sometimes it is just cross breeding plant species or just picking your best plants and breeding those, like you would with a horse. Anyone else know more add more to it. I'm sure I'm missing some things or correct me if I got something wrong, but I've a couple articles on it.

Also try googling genetically modified foods and you'll learn alot.
http://howstuffworks.com
http://google.com

I see this thread got moved.
« Last Edit: May 10, 2005, 09:41:46 PM by constant thinker »
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savoy7

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Re:Genetically modified foods
« Reply #2 on: May 10, 2005, 11:41:54 PM »
Laxbaby,

Whether you know it or not, your question is very broad.  I'll try to scratch the surface of it.  

How does genetically modified/engineered plants relate to chemistry?  The DNA that is modified is a molecule.  In modifying it, enzymes and chemicals are used in the process.  Usually the outcome is a different enzyme, deactivating an enzyme or adding a protein of some sort to the plant.  

Process:  I'll talk about older techniques and new ones.
 
Accumulation selection:  People don't usually call this genetically modified.  This is selectively crossing plants to get the qualities you want.  Sometimes you see the word hybrid used in the process.  
Good thing - easy to do, has worked for thousands of years
Bad thing - can not add traits (proteins) that are from plants that are too genetically different

Vegetative Propagation:  I throught I'd put this in here because people have been cloning plants for years.  This is not usually called genetically modified.  Just cut off a branch or root and place it in water (more to it with many plants).  Easy to make thousands of clones.

Grafting:  I just wanted to be complete, so I put this in here too.  By splicing two or more plants together, the plant can exhibit qualities of both/all of the previous.  Used a lot in fruit trees.  Not genetically modified.

Genetically modified-  plants have DNA from other organisims inserted into it.  This DNA will pass on to it's viable offspring.  Examples:  Golden Rice - rice is one of the most eaten grains on this planet.  Many malnourished areas of the world have access to rice.  Malnourished people are more susceptible to blindness.  Golden Rice has beta carotine (the DNA is inserted into it) in it.  Flavor savor tomato & lipooxygenase free soybeans.

If you want to learn more about them; do a word search on those examples.  There are lots of genetically modified plants.

Technique:  Different techniques - here's two quick ones

Put DNA fragment of desired trait into a plasmid (extra-cellular bacterial DNA).  Get plasmid into a vector (Agrobacterium tumefaciens).  Infect plant with vector.  The chemistry involved with this is:  isolating the DNA for the gene, cutting into the plasmid (restriction enzymes, buffered solutions, more enzymes - etc), and getting the plasmid to be "taken up" by the vector (pH and salt dependent).

Another technique I've seen, but not done.  Get desired DNA.  Coat pellets with it.  Shoot the pellets into the plant.  Some of the DNA will transfer.  Agricitus (spelling) of Madison, WI, was doing this technique in the mid 90's.  

Lots of info here that if you want a specific answer you can do a search on or just post a more specific question.
savoy

Offline Donaldson Tan

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Re:Genetically modified foods
« Reply #3 on: May 10, 2005, 11:50:54 PM »
selective breeding is the most primitive form of genetic engineering. however, its shortcoming is that the breeder must select for a gene already present in his gene pool. genetic engineering today aims to extend the gene pool artificially. this is done by artificially creating genes or inserting genes from other organisms into the DNA of the organism of interest.

alot of (bio)chemistry is involved in modern genetic engineering. from identifying the gene of interest, to duplicating it thousand times and over, and inserting into the organism DNA. chemistry is involved in testing for chemical substance that indicate that the inserted gene has expressed itself in the organism.

After identifying the gene of interest, restriction enzymes are used to splice the DNA to extract that particular gene. This gene will be replicated thousand times over using a technique call PCR that uses the DNA polymerase.

other examples of (bio)chemistry would be anti-sense technology. it is used in GM tomatos to prevent their over-ripening. the gene responsible for ripening tomatoes is repressed by an anti-sense gene. if the ripening gene DNA code is ATCG, then the anti-sense gene code is TAGC. During the DNA transcription process, the mRNA produced by transcripting the anti-gene will bind to the mRNA produced by the ripening gene. This binding of the two mRNAs happen via hydrogen bonding. In this way, no useful mRNA is produced for protein synthesis, thus the GM tomatoes cannot be ripened.
« Last Edit: May 11, 2005, 01:01:32 AM by savoy7 »
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GCT

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Re:Genetically modified foods
« Reply #4 on: May 11, 2005, 11:18:46 AM »
Not so much of the chemistry aspect of it that's important, but that of genetic engineering.

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