Protein Synthesis Simulator — DNA to mRNA to Protein
Simulate the central dogma step by step. Enter a DNA coding strand and see it unwound, transcribed to mRNA, read codon-by-codon with tRNA anticodons, and translated into a polypeptide chain. No signup, runs entirely in your browser.
Protein Synthesis Revision Tips
Template vs coding strand
The template strand is read by RNA polymerase during transcription. The coding strand has the same sequence as the mRNA (with T instead of U). This simulator uses the coding strand as input to match exam convention.
Codon degeneracy
The genetic code is degenerate — most amino acids are encoded by more than one codon (e.g. Leucine has 6 codons). This redundancy means many point mutations in the third codon position are silent and do not change the amino acid.
Frameshift mutations
Inserting or deleting a nucleotide shifts the reading frame, changing every codon downstream. This typically produces a non-functional protein. Substitutions only change one codon; frameshifts affect all subsequent codons.
Post-translational modification
After translation the polypeptide is often folded, cleaved, glycosylated, or combined with other subunits to form the final functional protein. The simulator shows the primary sequence — folding into secondary/tertiary structure is a separate step.
Frequently Asked Questions
What is transcription?
Transcription is the process of copying a DNA sequence into messenger RNA (mRNA) in the cell nucleus. The DNA template strand is read 3'→5' and the mRNA is synthesised 5'→3'. Thymine (T) in DNA is replaced by Uracil (U) in mRNA.
What is translation?
Translation occurs in the ribosome. The mRNA sequence is read in triplets called codons. Each codon is recognised by a tRNA molecule carrying the complementary anticodon and the corresponding amino acid. The chain of amino acids is the polypeptide.
What is a start codon?
AUG is the start codon that initiates translation. It also codes for the amino acid Methionine (Met). Every protein begins with AUG, though the initiating Met is often cleaved afterward by post-translational processing.
What are stop codons?
UAA, UAG, and UGA are stop codons. They do not code for an amino acid — instead they signal the ribosome to release the polypeptide chain. Translation ends when the ribosome reaches one of these three codons.
What is the central dogma?
The central dogma of molecular biology states that genetic information flows from DNA → RNA → Protein. DNA is transcribed into mRNA; mRNA is translated into protein. Reverse transcriptase (in retroviruses like HIV) can reverse the first step.
Is my DNA sequence stored?
No. All processing runs locally in your browser. No data is sent to any server.