In this flashcard video, we're going to go over melting temperature.
Melting temperature is the temperature at
which 50% of the DNA molecules and solution are denatured.
When we're talking about the denaturation for DNA,
we're referring to the double-stranded DNA
molecules separating into two
individual single-stranded DNA molecules.
So the melting temperature is the temperature at which
50% of the DNA molecules and solution
are separated into a single-stranded DNA molecules.
Now, the melting temperature depends on two factors.
The first factor is what we call GC-content.
Remember that DNA has two types of
base pairs: GC-base pairs
and AT-base pairs.
AT-base pairs are held together by two hydrogen bonds,
whereas GC-base pairs are held together by
three hydrogen bonds.
What this means is, the higher the percentage
of GC-base pairs in your DNA sequence,
the higher the melting temperature because you
have more hydrogen bonds.
The second factor that the melting
temperature depends on is the length of the DNA molecule.
This is simply because the longer the DNA molecules,
the more hydrogen bonds you have.
So similarly, this means the longer
the DNA molecule, the higher the melting temperature.