I wanna spend some time now
talking about the pathway
of gluconeogenesis. This is the
way that cells makes glucose
and this pathway is very very important,
especially for a multicellular organism.
Multicellular organisms have a
fairly constant need for glucose.
Our eyes need it pretty badly. Our brains
needs it and they don't have ways
of producing it. So maintaining
glucose concentration is important.
There is two ways that we can get
glucose. We can get it from our diet
and we are not constantly eating even
though sometimes it might feel like that
and we can also get it from synthesizing intake
and that's where gluconeogenesis comes in.
So gluconeogenesis kind of fills in the gaps
when we are not filling
them in by filling our stomachs.
It's important for cells to be able to control
gluconeogenesis; because, it's the opposite of glycolysis.
And we don't want to have a breakdown
pathway going on at the same time
as a synthesis pathway. So one of the ways in which
this pathway is regulated is through localization.
It turns out that in our body, gluconeogenesis
doesn't even occur in every cell. It occurs
primarily in our liver and our kidneys.
And even within those cells there is some
localization of the enzymes, as we shall see.
Now the reactions of gluconeogenesis,
there actually are 11 reactions
of gluconeogenesis, and I will talk about those
specifically the different ones in this discussion.
Last I will talk about
regulation. So let's get into it.
The synthesis of glucose, as I said, was
important for regulating blood glucose.
And so we have reactions in gluconeogenesis that occur
within a cell that actually does gluconeogenesis
in the cytoplasm, in the mitochondrion,
and the endoplasmic reticulum.
You recall that all the reactions of
glycolysis occurring in the cytoplasm.
In the body, as I said, we make glucose in
two primary organs, the liver and the kidney.
And the liver of the two is pretty much the most important because
it helps modulate all kinds of nutritional needs in our body.
Now in gluconeogenesis there are 4 reactions
that replace 3 reactions in glycolysis and they
are the ones we will focus on for this talk.
All the other reactions are simply the reverse
of glycolysis reactions. They are 7 of them.
In glycolysis we had 10 reactions
and gluconeogenesis we'll have 11.
So to make a glucose, glucose has 6 carbons,
we need two molecules of pyruvate because
there is 3 carbons in each pyruvate.