A cell stores the basic information it needs to do everything it
can do in DNA codes - genes - that can be used to make all of
its proteins, including enzymes used to make almost everything
else. But it doesn't carry a bunch of separate pieces of DNA -
the genes are stuck together on chromosomes. cell makes
offspring cells, all of the genes need to be copied, and a copy
of each needs to get into each new cell. The fewer pieces that
must be copied and distributed, the better the chance that it
will be done properly. This is why genes are linked together on
chromosomes. Chromosomes also carry other important pieces -
stretches that control how genes are read and spliced, stretches
that allow interactions when other genes are activated,
stretches that code for many different types of functional RNA.
There is also a lot of DNA in a chromosome whose function, if it
exists, is unknown - those are often used for genetic
comparisons, since mutations in a non-functional part of a
chromosome should be passed along to o