This represents a pair of nucleotides, basic subunits (monomers) which can be built up to make up the DNA molecule (a biological polymer). The molecules shown here are basically one rung of the DNA ladder.
Each nucleotide consists of a 5-carbon sugar deoxyribose unit attached to a phosphate unit at one side and one of four nitrogen-containing bases on the other side.
In this view two nucleotides, adenosine phosphate and thymidine phosphate, are shown:
Adenine (written as A
in DNA coding) is a purine
- with two rings, and thymine (T
) is a pyrimidine
- with one ring. 2 hydrogen bonds
between these sections hold them together.
Each nucleotide appears to be upside down compared with its partner, and that includes the deoxyribose and phosphate units. This is because the 2 DNA strands are built up from alternating sugar-phosphate strands pointing in opposite directions:
Show bases from the edge
show oxygens in deoxyribose rings
projecting oxygens in phosphates
turn back to show bases in face view
Colour by chain
Colour AT pairs