Name: Dan DeVito
Date: March 2004
Why are most harmful genes recessive? What
would happen if they were dominant?
Why are most harmful genes recessive? What would happen if
they were dominant?
The most harmful genes are recessive because that is really
the way they can survive. If a harmful gene were dominate,
the individual likely won't live long enough to have
offspring (although modern medicine is changing this
situation). That's why dominate harmful genes are so rare.
(Look up how Sickle Cell Aenima has survived if you want
want a really cool harmful genetic disorder that has a very
big advantage to some of those who carry it).
Recessive genes are pretty cool because they are able to
hide within a population, without falling out of a gene
pool. (It's important to keep in mind that recessive genes
are as likely to fall out of a gene pool as dominate
genes). For instance - my dad has blue eyes, and my mom
has brown eyes. I have brown eyes but I am carrying the
blue eye gene - but it doesn't show up. I am as likely to
pass on my dominate brown eyed gene as my blue eyed gene -
thus the survival of either is 50/50. The same goes for
harmful genes. They are able to survive in the gene pool
and are able to be passed on because they, like my dad's
blue eyed gene, are able to hide. Unless I marry someone
who also has a blue eyed gene (ha! - if only I can find a
sucker) then there is no way my blue eyed gene could show
up. Harmful recessive genes work the same way.
It's for this reason that testing oneself of genetic
disorders before having babies isn't a bad idea, especially
if harmful genetic diseases have shown up in your family.
Two individuals could be carring a very nasty recessive
gene and have NO CLUE it's in the genetic make-up - but
could easily show up in their children. Good mechanism for
hinding and survival, don't you think?
Hope that helps!!
Susie Sample B.S.B.M.E.
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Update: June 2012