|When do cells duplicate their DNA?|
|Question Date: 2017-03-02|
The short answer is before they divide. But
it’s not that simple. Some cells don’t divide
much, or at all, after we’re born. Our muscle and
nerve cells are like that. Other cells, like our
skin cells, divide fast and keep dividing all our
lives. They do slow down as we age.
A new cell (which was just created by a cell
dividing) starts off by growing. It has to take on
nutrients for the building blocks of new cell
parts, and the energy to do the work of building
them. That is the first growth phase (G1). Then
the DNA replicates. This is called the
synthesis (S) phase because new DNA is being
synthesized (made) using the original DNA as a
pattern, or template. Then there’s
anothergrowth phase (G2). The cell is
making things it needs in order to divide.
Mitosis is the process where the DNA gets
divided evenly between the two halves of a cell.
Then the cell actually splits. The split is
called cytokinesis. “Cyto” means “cell” and
“kinesis” means “moving.” The result is two cells
that are basically identical to each other, with
each one being half the size of the cell that just
There is a different process used to make gametes
(egg and sperm cells).
You may want to study cell biology.
Thanks for asking,
Cells duplicate their DNA when they decide they
need to divide. Cells divide for three main
reasons: growth, repair, and reproduction. This
could be during mitosis or meiosis. Mitosis
is the dividing of your non-reproductive cells,
and meiosis is the dividing of your reproductive
cells. In mitosis, there is a phase that happens
before the cell divides called interphase.
Interphase can be further broken down into the G1,
S and G2 phase. G1 phase causes the cell to
grow in size and produce new organelles, which
prepare for S phase, when the DNA replicates.
Cells will duplicate or copy their DNA right
before they divide. The process of cell
division is called mitosis. Since the cell
is dividing it needs two copies of its DNA - one
is kept by the parent cell and the other is passed
to the daughter cell. If cells don't replicate
their DNA or don't do it completely, the daughter
cell will end up with no DNA or only part of the
DNA. This cell will likely die. So this process of
duplicating DNA is very important. Cells also copy
their DNA right before a special cell division
event called meiosis, which results in special
cells called gametes (also known as eggs
Are you familiar with the cell cycle? It
describes the process by which cells grow and
divide to make new cells. Since every cell
needs a copy of DNA then cells need to replicate
their DNA at some point before they divide.
There are four main phases in the cell cycle
that describe the times the cell is growing and
then making new cells. These stages are
G1,S, G2,and M. I know this
already sounds a little complicated, but that’s
ok, once you have all the information this idea
should be a little clearer.
G1 is the first growth phase where
the cell just grows bigger. This phase also serves
as a checkpoint where the cell can make sure it’s
ready for the next step which is S phase. The S is
for synthesis which is where the DNA replicates
itself so the cell has two copies of DNA. The next
phase is G2 which is another phase of
growth. At this point the cell checks itself
again, makes sure it is big enough and ready to go
into the M phase. M phase stands for
mitosis which is where the cell goes through a
lot of complex steps in order to split into two
Since the cell cycle is a circle, both
daughter cells can then move straight into
G1 phase to start the cycle all over
again. Phases G1, S, and G2
are all collectively called “interphase”
which is just a fancy word for “not
mitosis”. The cell cycle can be a really
difficult idea to wrap your head around but asking
questions like these is the first step toward
understanding science better. Thanks for the
Cells duplicate DNA during interphase, usually
shortly before entering either mitosis or meiosis
(eukaryotic cells) or fission (prokaryotes).
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