Explain the structure of a DNA polynucleotide strand

Think of DNA like 2 long shoelaces coiled around each other to form a spiral - or a double helix as it's called. Each of the 2 shoelaces is called a 'strand' and is made up of something called 'polynucleotides'. Poly means many, and a nucleotide is simply a few different components attached to each other. So a polynucleotide means many nucleotides attached to each other.

So each strand is made up of many nucleotides attached to each other, think of this like there being many knots back to back within the shoelace - where each knot represents a nucleotide. A nucleotide is simply a phosphate group, a pentose sugar (meaning it has 5 carbon atoms) and a nitrogenous base. Every nucleotide within DNA has a phosphate group, a deoxyribose sugar (this is the 5 carbon atom), and one of possible bases - Adenine (A), Thymine (T), Cytosine (C) and Guanine (G).