In this course, you will be dealing with a lot of sequence data. As you probably know, there are 4 building blocks for DNA and 4 for RNA that are called nucleotides. The two sets are almost the same but a little different. RNA has a ribose sugar, therefore RiboNucleic Acid. DNA is missing an OH group from the ribose sugar, therefore DeoxyriboNucleic Acid.
Pyrimidines have two rings and purines have one.
In RNA or DNA, a purine always base pairs with a pyrimidine and visa versa. G and C make 3. It is important to remember who base pairs with whom. It can be used as the basis for prediction. For example, observation of covariation in RNA molecules implies conservation of secondary structure.