Enzymes are critical in bringing substrates together in the correct
orientation and this is how they can decrease the activation energy.
So if we want to break glucose, it's nice to have an enzyme to grab
on to it and literally twig it a little bit so we can break it.
Here is an example that I'd like to use about decreasing
the activation energy or acting as a catalyst.
Let's say I'm the person in red in this image,
and I have a friend on one coast of the country,
and I have a friend on the other coast of the country,
and I think that they probably should get together.
They could eventually bump into each other
maybe somewhere else in the world
but I could decrease the time it took for them to
bump into each other simply by introducing them,
and then they fall in love
and they live happily ever after.
I have acted as a catalyst bringing my two friends together.
So my catalytic activity has helped them meet each other
much more quickly than they would had they left at two random chance.
So enzymes bring things together in the correct orientation
so that these metabolic reactions can continue inside the cell
at a rate that's acceptable to run cellular processes.
So enzymes act as a catalyst by grabbing onto a molecule,
in this case we've got a molecule with two parts to it
and the substrate fits into the enzyme.
The enzyme does its magic as an enzyme-substrate complex.
It may twig and twerk its protein molecules,
so it can twist and turn, and boom break the bond
and release this one molecule as two pieces.
So the enzyme has an active site that fits one molecule, or it could
work in the other direction where the two molecules come in
it twigs and pops and add some energy and sticks those together.
So enzymes are critical to having metabolic pathways work.