Imagine that you had a cookbook with the best
recipes of your grandparents and other ancestors.
It’s very important to you and you don’t want to
damage it, but you want to use one of the recipes.
What would you do? You’d probably copy the
recipe you needed and keep the original cookbook
in a safe place.
Why am I talking about cookbooks? Well,
your complete set of DNA, your genome, is
basically a set of recipes passed down to you
from your ancestors. Almost every one of your
cells has a complete copy of the genome in its
nucleus. It stays safe in the nucleus all the time
unless the cell is dividing. But the cellular
machinery that “reads” the “recipes” to make
proteins are out in the cytoplasm. So how do
you get the code into the cytoplasm?
Messenger ribonucleic acid, or mRNA, is like
the copy of a recipe. RNA is similar to DNA,
but it is only one strand instead of being a
double helix. And mRNA is a lot shorter
because it only copies one “recipe” instead of the
whole “cookbook.” Most cells only need to use
a tiny fraction of the genome.
Using mRNA also means that you can make a lot
of proteins in a big hurry. Each cell usually
only has one copy of any “recipe,” but a whole lot
of copies of mRNA can be made from the same
stretch of DNA. That would be like taking that one
recipe, making a bunch of copies, then giving them
to lots of helpers. You’d get a lot more made.
So the mRNA takes the “recipe” out to cytoplasm
to ribosomes, which are usually called the
workbench of protein synthesis because it’s where
the “recipe” is used to put the right amino acids
into the right order to make a protein. Sometimes
the protein is ready to go and do its job. At
other times, it needs some editing first.
Two other types of RNA take part in
translating the mRNA message into the
string of amino acids. The ribosomes are made
of RNA. There are also transfer RNAs that are
a sort of decoder of the mRNA.
So, long story short, RNA is necessary for your
body to make the proteins that give you
structure, let you move (muscles), send
signals (hormones), have chemical reactions
(enzymes), fight infections (antibodies) and lots
of other things that make life possible.
Would it be worse for a mistake to happen when
RNA is being made or when DNA is being made so
that a cell can divide?
Thanks for asking,
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