Structure of RNA
RNA is a type of nucleic acid called ribonucleic acid:
- RNA The units or molecules of which DNA is composed. are joined to form a single strand.
- Nucleotides are joined together by a strong covalent bond between the sugar of one nucleotide and the phosphate of the next.
RNA differs from DNA in the following ways:
- RNA is single stranded while DNA is double stranded.
- RNA has a sugar called ribose while DNA has a sugar called deoxyribose.
- RNA has the base uracil while DNA has the base thymine.
Type of RNA
There are three types of RNA involved in gene expression.
mRNA - Messenger RNA is a linear molecule which carries a copy of the gene to be expressed from the nucleus. Every group of three bases (a 'triplet') is described as a codon because each one codes for an amino acid.
tRNA - Transfer RNA has a cloverleaf shape. It is made from a single strand of RNA which folds due to base pairing to form this unusual shape. It has a triplet anti-codon site and an attachment site for a specific amino acid.
rRNA - Ribosomal RNA and proteins form the ribosome. The ribosome is the structure where protein synthesis takes place.