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Practice English Speaking&Listening with: MCAT Flashcard: Melting Temperature

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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.

The Description of MCAT Flashcard: Melting Temperature