Protein Synthesis Definition
The nucleotides with an X in front of them are an example of a DNA sequence that would be used to code for a specific protein. Only one strand of every DNA molecule is the coding strand, which contains the information for protein sequences. The template strand is the complimentary strand on which the RNA nucleotides line up to create a copy of the DNA coding strand. These nucleotide sequences are utilized to produce amino acids, which are joined together to form proteins.
mRNA and Protein Synthesis
Although most genetic information is stored in the nucleus of eukaryotes, protein synthesis takes place in cytoplasmic ribosomes, either as free ribosomes or on the rough endoplasmic reticulum. The genetic information in the nucleus must be transmitted to these ribosomes in order for protein to be produced. mRNA is responsible for this (messenger ribonucleic acid). It’s extremely similar to DNA, but there are two key differences.
- In mRNA, the nucleotide uracil replaces the base thymine in DNA.
- In DNA, the sugar deoxyribose is replaced by mRNA’s sugar ribose.
The double helix shape of DNA uncoils at the start of protein synthesis, much like it does during DNA replication, allowing mRNA to duplicate the genetic sequence responsible for coding a specific protein. The DNA has uncoiled at the start, allowing the enzyme RNA polymerase to enter and transcribe (copy) the genetic material into mRNA.
If the coding strand of DNA is G-G-C-A-T-T, then the template strand would be G-G-C-A-T-T. The mRNA would be G G C A U-U and the codon would be C C G T T A. (remembering that uracil replaces thymine). The mRNA strand travels out of the nucleus and away from the DNA, towards the ribosomes, now that the genetic information required to create substances is available on the mRNA strand.
Protein Synthesis Citations
- Skeletal muscle and resistance exercise training; the role of protein synthesis in recovery and remodeling. J Appl Physiol (1985) . 2017 Mar 1;122(3):541-548.
- Protein synthesis and quality control in aging. Aging (Albany NY) . 2018 Dec 18;10(12):4269-4288.
- Protein Synthesis Initiation in Eukaryotic Cells. Cold Spring Harb Perspect Biol . 2018 Dec 3;10(12):a033092.
- Figures are created with BioRender.com