Base Pairing of Nitrogenous Bases

The structure of DNA consists of two strands of nucleotides that are paired together to form a ladder-like structure.  One strand of DNA is the template from which the other one is built.  The nitrogenous bases of each nucleotide pair together in specific combinations in order to form the structure of DNA. Each rung of the ladder is a pairing of nitrogenous bases.

The types of nitrogenous bases that make up RNA and DNA molecules:

DNA:

Thymine (T) pairs with Adenine (A)

Guanine (G) pairs with Cytosine (C)

Example:

If this text was one half of a DNA Strand:

A

G

A

A

T

T

C

G

C

The pairs of nitrogenous bases would look like this:

A--T

G--C

A--T

A--T

T--A

T--A

C--G

G--C

C--G

Image: A DNA strand.

RNA nucleotide pairs are the same as DNA pairs, however RNA does not contain the Thymine (T) nitrogenous base.  Thymine is replaced with Uracil (U).

RNA:

Uracil (U) pairs with Adenine (A)

Guanine (G) pairs with Cytosine (C)

Example of RNA pairing during protein translation:

A-U

G-C

A-U

A-U

U-A

U-A

C-G

G-C

C-G