There are a few things you need to know before doing this
- Every polypeptide is created by a series of amino acids.
- These polypeptide are then used to create protiens.
- Every gene codes for one polypeptide.
- A codon is 3 base pairs that codes for one amino acid
To start, you need to find how many amino acids are in the polypeptide, in your case of 12 base pairs, its 4. How did I get this? Well firstly you need to divide the number of base pairs by 3 to get the number of codons and since each codon codes for one amino acid, we find that this number is also the number of amino acids in the polypeptide.
Now that you have this number, you need to make the diagram. The diagram consists of two parts: transcription and translation.
Transcription is where the DNA "unzips" and an enzyme aids in the production of mRNA. This all takes place in the nucleus.
Translation is where the mRNA attaches to a ribosome. This then creates tRNA which gathers amino acids floating around in the cytoplasm and brings them back to the ribosome which connects them in the correct order.
Hope that helped