Structurally speaking, RNA and DNA are different. One clear distinction between the two is that RNA is single stranded, while DNA is double stranded. Another way they differ is found in their nitrogen bases. The four bases for DNA are Adenine, Thymine, Cytosine, and Guanine (think, ATCG). The bases for RNA are the same, except Thymine is replaced with Uracil (think, AUCG).
Another note is that RNA polymerase is unable to detect errors in base pairings, unlike DNA polymerase, but their syntheses are both in the 5’3’ direction. Hopefully this helps you answer this question.
The RNA primers are required during the initiation process of the DNA replication. These primers acts as the template for the further process of the DNA replication.
These RNA primers must be replaced as RNA is quite different from DNA. The oxyribose pentose sugar is present in RNA structure while deoxyribose pentose sugar is present in DNA. The nitrogenous bases present in RNA are adenine, guanine, cytosine and uracil and thymine is present in DNA instead of uracil. RNA is highly unstable in nature than DNA.
