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DNA is the molecule that carries the genetic information of
all living things.
See these topics in Life's Big Instruction Book: What's that? |
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No. DNA is found in all living things, including people and all foods
people eat. In fact, beer and wine contain large amounts DNA from the
yeast that made it, because it's hard to filter it out. DNA is a
passive molecule: without a lot of help from other biological
molecules, it doesn't do anything.
See these topics in Life's Big Instruction Book: What's that? |
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No more so than from other living things, which is to say, no. For genetic
engineering to work, the new DNA added to a living thing has to be very
similar to what's already in it. All of the features found in DNA used
for genetic engineering already exist in living things. In fact, presently
all the DNA used in genetic engineering comes from living things (though it
may be modified by mutations) and most genetic engineering is done by
natural methods.
See these topics in Life's Big Instruction Book: What's that? |
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No, and there are two parts to why not. First, DNA, regardless of
source, can't alter other DNA without help from other things, such as being in
a retrovirus or being subject to techniques found in the laboratory. DNA
a person is likely to normally encounter -- in food or in other living
things -- has neither the right features nor the right help to pose any
danger. This is an imaginary risk.
But suppose that some bit of DNA could mutate other DNA in some way we don't presently understand. This leads into the second part of why not. Nearly all organisms try not to have anything to do with DNA they find floating around in their environment. (An important exception to the rule.) Plants and animals secrete proteins (called nucleases) on their skins that destroy DNA that bumps into them. If DNA were to somehow get by this first line of defense -- getting in through an open wound, say -- it would run into similar defenses that are part of the organism's immune system that will destroy it. If even if the DNA gets by the immune system, it can't get into the organism's cells, which is where living things keep their DNA. But even if it could get into the cells, we come back to the beginning of why not: DNA just can't do anything by itself. Even if DNA got through all these barriers and was pressed up against the DNA in a living thing, it would just sit there until the organism's DNA-recycling proteins noticed it and broke it down. Finally, even if the DNA could somehow interact with the new organism's genome, the new organism is unlikely be able to turn on its genes, as the genes probably don't have the right promoters to get the attention of the organism's activators. Also, humans, like most animals, have immune systems that look for new genes and try to get rid of them. Since all food contains DNA, we'd know by now if it could affect us. This is especially true of beer and wine, which have lots of DNA from the yeast that makes them. No beer or wine drinker has suffered any affect from the DNA in their drink. See these topics in Life's Big Instruction Book: What's that? DNA, promoters, activators, genome, cells, proteins mutations, mutagens, retroviruses, genetic engineering |
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There are two parts to the answer. First, there isn't ever any DNA
"left over". Any DNA that doesn't get integrated into engineered
organism's genome is simply broken down by the organism. Second, even
if that DNA were to persist in that organism (by some route we've
never seen before), it wouldn't matter. All of the genetically
engineered organisms you could encounter outside the laboratory are
the offspring of the ones that were engineered -- so this hypothetical
bit of DNA isn't in any of them.
(And also see the discussion under Can DNA (from genetically engineered organisms) mutate me?.) See these topics in Life's Big Instruction Book: What's that? |
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Mutation is a catch-all term for any change in DNA. Mutation
occurs constantly in living things, despite their attempts to prevent it.
Many organisms even intentionally mutate.
See these topics in Life's Big Instruction Book: What's that?
mutation,
mutagens
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Whether a mutation is good or bad depends on how it changes DNA
relative to the living thing's situation. While mutations are often
thought of as bad because they can destroy genes organisms need,
without mutations, organisms can't improve by evolving.
See these topics in Life's Big Instruction Book: What's that? |
See these topics in Life's Big Instruction Book: What's that?
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