RNA Structure
- Like DNA, the nucleic acid RNA (ribonucleic acid) is a polynucleotide
- It is made up of many nucleotides linked together in a long chain
- RNA nucleotides contain the nitrogenous bases adenine (A), guanine (G) and cytosine (C)
- Unlike DNA, RNA nucleotides never contain the nitrogenous base thymine (T) – in its place they include the nitrogenous base uracil (U)
- RNA molecules are only made up of one polynucleotide strand (they are single-stranded)
- Each RNA polynucleotide strand is made up of alternating ribose sugars and phosphate groups linked together, with the nitrogenous bases of each nucleotide projecting out sideways from the single-stranded RNA molecule
- Examples of an RNA molecules are:
- messenger RNA (mRNA) which is the transcript copy of a gene that encodes a specific polypeptide
- transfer RNA (tRNA) which is involved in protein synthesis
- ribosomal RNA (rRNA) which forms part of a ribosome
Messenger RNA (mRNA) provides a good example of the structure of RNA
Examiner Tip
- The main differences you need to know between RNA and DNA:
- RNA is single-stranded
- RNA contains uracil instead of thymine
