Complete the paragraph
Fill in the blanks by selecting the correct word from the bracket and complete the given paragraph.
(adenine, phosphoric acid, centromeres, cytosine, nucleotides, ribonucleic acid, guanine, thymine)
In 1953, Watson and Crick produced a model of the DNA molecule. As per this model, each strand in the molecule of DNA is made up of many small molecules known as _________. There are four types of nitrogenous bases adenine, guanine, cytosine and thymine_________and __________are called as ‘purines’ while _________and_________ are called ‘pyrimidines’. In the structure of the nucleotide, a molecule of a nitrogenous base and _________are each joined to a molecule of sugar.