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Hi! So today, we are going to start off
this entire lecture series by introducing to you stem cells,
and hopefully, after this entire lecture series,
you will realize that they are pretty cool things.
So let’s start!
So what are stem cells,
and how do they differ from other cells in our body?
Stem cells have three unique features.
Firstly, they are unspecialized.
This means that our stem cells do not have
tissue-specific features for it to
perform any particular function.
We can contrast this to specialized cells,
such as our red blood cells,
which have the tissue-specific feature of
containing haemoglobin that enables cells to transport oxygen.
Secondly, stem cells undergo
extensive proliferation and self-renewal.
By self-renewal,
I mean that stem cells can make more stem cells by division.
Previously, you have learnt about mitosis,
and stem cells are capable of dividing and renewing themselves
numerous times by mitosis.
And each daughter cell will have the same
developmental and replicative potential as their parent cell,
which pretty much means that they share
the same properties as their parent cell.
Thirdly, and most importantly,
upon receiving appropriate molecular signals,
stem cells are able to differentiate themselves to
produce specialized cells.
Differentiation refers to the process
in which less specialized cells become a more specialized cell.
There are two ways in which a stem cell can divide,
namely symmetrical and asymmetrical division.
If it undergoes symmetrical division,
it would generate two daughter stem cells,
so pretty much you have an increase in the amount of stem cells,
pretty straightforward.
However, if your stem cell is stimulated by
certain molecular signals for differentiation,
asymmetrical division would occur.
This process will give rise to one daughter stem cell
and one specialized daughter cell,
and the type of specialized daughter cell generated
will depend on the population of stem cells.
For instance, neural stem cells will give rise to neurons,
or neuron support cells.
As previously mentioned,
asymmetrical division gives rise to a daughter stem cell,
and a specialized or differentiated daughter cell.
The presence of the daughter stem...
daughter stem cell
ensures that there is a constant pool of stem cells
and the presence of a specialized or differentiated
daughter cell ensures that your population of
specialized cells in a specific tissue is renewed.
So, at this checkpoint,
you should be able to describe how stem cells differ
from other cells in our body.
Also, you should also be able to describe
two possible ways of division that stem cells can undergo,
as well as the product of the division.