Structure of RNA

RNA is a polymer of nucleotides. Unlike DNA, however, RNA is single-stranded. Also, the base thymine is replaced by the base uracil and the sugar ribose is used instead of deoxyribose.

There are three kinds of RNA.

• Messenger RNA (mRNA) carries a copy of the DNA code to the ribosomes during protein sythesis.
  
  
• Transfer RNA (tRNA) transports amino acids (used to form proteins) to their proper place on the mRNA template.
  
  
• Ribosomal RNA (rRNA) are the building blocks of ribosomes. They are created in the nucleolus.