So all of these comes together in biochemical pathways.
So why are we exploring all these enzymes
and why that we spend all this time looking at thermodynamics?
Not because I really want to confuse you but they are
important principals to understand
in order to get a grip on
how biochemical pathways can work and be regulated.
All the biochemical pathways are considered our metabolism. We will
be spending some time looking at the process of cellular respiration
in brief because really it's the content of biochemistry
to look at the extreme details of it
but we'll recap some of the main points as they relate to biology.
Before we do, we need to understand
what biochemical pathways involve.
They usually involve a sequence of enzymes such that
we have a substrate that binds into the first enzyme in the pathway
and it comes out transformed into a different molecule
or cut into two pieces or however that enzyme functions.
And that goes into the next enzyme and that enzyme does something
to the substrate and turns it into a different product
and then that product becomes the substrate for the next enzyme
and so on and so forth until eventually we get an end product
in the biochemical pathway.
Now the neat thing about this is sometimes these biochemical pathways
regulate themselves in the mechanism of negative feedback.
I believe that I've introduced you the negative feedback before
but here's a real life example.
We have our protein, enzyme, taking a molecule that's a substrate,
changing it, changing it, changing it.
We move down the pathway, we eventually get our end product
And that very end product could, guess what, come back and
be an allosteric inhibitor for an enzyme earlier in the pathway.
Once it ... , could be a competitive inhibitor.
Either way, it's going to shut the active site,
so the active site doesn't work properly
and therefore the substrate cannot binds to that enzyme
and the production of the product is shut down.
So a great example of negative feedback.
So in this lecture, I've introduced you
to some foundational concepts
that are going to help us understand
the specifics of cellular respiration.
We should now be able to define the laws of thermodynamics
as they apply to free energy,
recall free energy is the energy available to do stuff in our cells.
We may increase free energy in reactions
or decrease free energy in reactions.
In addition, you should be able now to explain the roles of enzymes
in lowering activation energy in biochemical pathways,
which we call metabolism.
Thank you so much for your attention. I look forward to taking you
on the rest of the tour through the metabolic processes.