DNA, RNA, & Proteins. The shape of DNA. A DNA molecule is shaped like a spiral staircase and is composed of two parallel strands of linked subunits. The spiral shape of DNA is known as a double helix. Each strand of DNA is made up of linked subunits called nucleotides.
A nucleotide is made up of three parts: a phosphate group, a five-carbon sugar group, and a nitrogen-containing base.
Gene expression produces proteins by transcription and translation. This process takes place in two stages, both of which involve RNA.
The second stage of gene expression is called translation. Translation uses the information in RNA to make a specific protein.
At the site of translation, transfer RNA (tRNA) “reads” the instructions carried by the mRNA, then translates the mRNA sequence into protein subunits called amino acids.