What is the function of the start codon?
The start codon is a crucial component of the genetic code that signals the beginning
of protein synthesis. The start codon is responsible for initiating the translation
process by providing the necessary information for the ribosome to locate the correct
reading frame for the mRNA transcript.
The most common start codon in the genetic code is AUG, which codes for
methionine. Other start codons, such as GUG and UUG, exist in some organisms,
but AUG is the most prevalent.
After recognizing the start codon, the ribosome joins the two subunits and begins the
process of protein synthesis. The tRNA molecule carrying the amino acid methionine
enters the ribosome and is positioned at the start codon. The ribosome then moves
along the mRNA transcript, reading the codons and synthesizing the protein based
on the sequence of nucleotides.
In summary, the start codon plays a critical role in the process of protein synthesis
by initiating the translation process and ensuring that the ribosome starts at the
correct location on the mRNA transcript.
References:
1. Alberts, B., Johnson, A., Lewis, J. et al. Molecular Biology of the Cell. 4th edition. New
York: Garland Science; 2002.
2. Lodish, H., Berk, A., Zipursky, S.L. et al. Molecular Cell Biology. 4th edition. New York: W.
H. Freeman; 2000.