Video Transcript
What type of bond forms between
complementary base pairs in DNA?
DNA is a biological macromolecule
that stores our genetic information. It’s made up of two complementary
strands that are twisted around each other to form a double-helix shape as we can
see here. Let’s zoom in on its structure so
we can get a better look and answer our question.
Here’s a close-up of the structure
of DNA. You can see the two strands
indicated here. Each strand of DNA is made up of
repeating subunits called nucleotides. There are three components to a
nucleotide: a phosphate group, a deoxyribose sugar, and a nitrogenous base.
In DNA, there are four nitrogenous
bases: guanine, cytosine, adenine, and thymine. These nitrogenous bases can pair
with each other to form complementary base pairs. We can see that here, where guanine
pairs with cytosine and adenine pairs with thymine. These bases pair with each other by
way of hydrogen bonds, which are indicated here as these black dots. These hydrogen bonds are what hold
the two strands of DNA together to form the double helix. Guanine and cytosine form three
hydrogen bonds, while adenine and thymine form two.
Therefore, the type of bond that
forms between complementary base pairs in DNA is a hydrogen bond.
