There are three different types of RNA:

1. Messenger RNA (mRNA): A messenger RNA molecule is a single strand (not a double strand) about a thousand nucleotides long. Massenger RNA is involved in carrying the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm where protein is synthesized.
2. Ribosomal RNA (rRNA): Molecules of ribosomal RNA are large and complex, often forming a double helix. Ribosomes are made up of rRNA and protein.
3. Transfer RNA (fRNA): These are small molecules, about 80 nucleotide long. Transfer RNA molecules bring amino acids to the ribosomes so that the protein can be assembled.