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I'm Martin Picard from
Today, I'll be telling you about
mitochondrial morphology and
ultrastructure in skeletal muscle.
Mitochondria are the origin
of complex life,
there are two main cellular
compartments that we can look into.
One of them is the cell nucleus which
contains the genes that encode for
proteins that provide structure for
the cells, and
if we look into the cytoplasm there
are organelles including mitochondria.
Mitochondria take the oxygen
that we breathe in and
the food substrates that we consume, and
transform these into cellular energy that
is necessary to power cellular activities.
An important point is
that the mitochondria and
the nucleus exchange information on
a regular basis, which is important for
the regulation of cellular responses
to stressors and to energy levels.
There is evolutionary evidence
that without mitochondria,
the ancestor of today's eukaryotic cell
could not have existed, and the evolution
of multicellular life required the
incorporation of the alphaproteobacterium
which was then to become
the mitochondria with its own genome.
That afforded sufficient amounts of
energy, we can see in the graph on
the bottom left in picowatts per genome,
the eukaryote which was able to evolve
complex multicellular life has
more energy per unit of cell.
But what do mitochondria look like?
Here we have a cell time-lapse image which
shows that mitochondria are extremely
dynamic organelles, mitochondria
are in fact living microorganisms that
populate the cell cytoplasm.
This big round structure in the middle
with the little cartoon of the chromosomes
is the nucleus, and that's where the
genetic material is contained and these
squiggly 'spaghetti' structures in the
cytoplasm are actually the mitochondria.
We can appreciate how dynamic they are,
how much movement there is, and
there are processes of fusion and
fission that are constantly happening.
Why is that relevant?