So we have our strand of single-stranded DNA
we have the 5" end at this end the 3" end at this end
which, of course, means that the new strand
is going to be 5' at the other side and 3'prime
so the other side, of course, is going to be backward
we have an adenine and we know at the adenine goes with thymine so let's.. but wait a minute
but how is this going to work
We have our triphosphate it's all energized and ready to go and ready go to work
I don't really see .....this one wants to go on this one
but that doesn't look like it's going to work
there is a little cheat that we are going to use here
which is also used in metabolism and that is that there is a primer
that is put on to start the whole program
Okay now let's look at
we got guanine and we have a cytosine that matches the base
and we've got a triphosphate so this guy is energized for the reaction
to be added to the base before it
The 5' with the phosphates attaches to the 3' on the previous one
okay that looks pretty good
We've got a thymine and thymine wants an adenine so we bring this guy in
the adenine looks like it will fit two of the phosphates are cleaved off
providing the energy to make the attachment
and this guy is hooked on 5' to 3'.
So we have two bases done so good we have two more
adenine goes to thymine down here but wait a minute wait a minute
we need ..... we need an energetic handle on the 3' and it is on the 5'
which means this guy is not going to go on there.
In DNA replication the 5' end hooks to the 3' end and it can't work the other way around
When looking at chemistry, science or maybe even anything you really need to think about the energy
what is driving this process where does the energy come from
In the world of cellular biology the big driver in the energy scene is ATP
ATP is like the primary energy source it's like ... it's like everything comes down to ATP
I think of enzymes as being like mechanical machines
they, like have levers and things that push and things that pull
maybe pulleys and levers and things that shift
ATP is like a tightly wound spring
and when it releases to ADP it makes a physical change
and then when it makes a physical change when the enzyme makes a conformational change
and is able to impact reactions that require Energy
....but it's done ....I think it's fair to look at it ... kind of as a physical sort of thing
there is like a physical tension in the ATP
and when that's released , that physical release can be used somewhere else to do something
In the world of energy, the energy always comes from the Sun
the Sun (light) comes down on plants, excites electrons
the electrons make.. like.. like.. hydrogen gradients and those hydrogen gradients
which are a form of energy, are used to make ATP
so ATP is like a primary energy source in the cell
one of the main uses for energy is that is used to make glucose
so it takes bunches of ATP through a long complex series of reactions ATP i.e. sun light
is made into glucose which is perhaps the primary actual storage unit of energy
which probably relates to the fact that sugar is fattening because it's a big energy storage unit
the primary unit, the primary working energy source, is the ATP itself
and then glucose is broken down to form ATP which is then used for things actually in the cell
so what does all this have to do with DNA structure
ATP is adenosine triphosphate
ATP is one of our nucleotides.
there's guanine triphosphate which is seen in metabolism sometimes
there is cytosine triphosphate, thymine triphosphate and uracil triphosphate
these guys are energized , ready to do reactions
let's take a look at this
we have the .....the sugar .. is here, of course
the phosphate is on the 5' end
the ATP.... the phosphate is on the 5'end
so we have the 5' phosphate, phosphate, phosphate
the 3' end doesn't have anything on it
the "deoxy" is on the 2'
and then the base comes out here
So DNA replication
during DNA replication, recall, the chromosomes divide, the DNA is all duplicated
I think it is cool