What makes you human or me a penguin? Genes. These are the instructions
for how to build a body which all living things have.
Tiny creatures like snails have them just as big animals
like whales do. So do all plants and other living things.
are very tiny clumps of information about how to make
parts of living bodies
a little like a recipe for
a cake or a music track on an old-fashioned cassette tape
or CD. But they don't just exist on their own. They are
packaged up in long strings called
like a whole music album on tape.
All these genes - that's all the instructions needed to
make you or me - are stuffed in the middle of tiny blobby
packets called cells. Cells themselves are very tiny but
as millions and millions of them stick together, what
we call a bodyScientists call this the phenotype
begins to form. That could be a snail, a whale; you or
me. (How this 'sticking together' happens is very complicated
and no-one yet understands it fully.)
When you grow, some of your millions of cells
split into pairs of identical new ones. Start with
one million and, whooo! - you've got two million - twice
as big! Now this is the clever bit: all the gene instructions
get copied exactly just before the cells split. This is
like copying your music album onto another blank CD to
give to your friend. So every cell of every body of every
living thing on the planet always has this gene body-building
information - the genetic code - inside it.
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