Biology 12 Protein Synthesis

  1. Unwinding and Unzipping

The DNA helicase enzyme separates the double DNA into singular strands and allows each of the strands to be copied onto RNA. The helicase continues to unwind the DNA positions that are called origins where synthesis can be initiated from. The Helicase continues to unwind the until the DNA starts to form into a fork like structure which is called the replication fork. The process of breaking hydrogen bonds between the two strands requires the energy from a molecule named ATP which serves as an energy currency of cells.Complementary base pairing

2. Complementary Base Pairing

The RNA polymerase promotes base pairing, and it makes sure that the right nitrogen bases are paired to create the right amino acids. The DNA that is copied is now turned into the mRNA which makes it so that there is a different nitrogen base and that is the reason for having the polymerase. The Polymerase shows the right bases are bonding together.

  1. Separation From DNA

Once the mRNA Strand is complete and had bonded together, it detaches from the DNA becoming its own and is left by itself, but the new mRNA is not ready for translation because it is not mature enough to leave the nucleus on its own.

 

Translation

 

  1. Initiation

After transcription is completed in the nucleus, mRNA exits through a pore and enters the cytoplasm.  At the area on the mRNA containing the start codon, both the smaller and larger subunits of the ribosome bind to the newly formed mRNA. These are then joined by the tRNA which contain the anticodon which match the start codon on the mRNA.

  1. Elongation

The tRNA brings the amino acids to the growing polypeptide according to the correct base pairing by the mRNA codons and the anticodons provided by the tRNA. Then the tRNA moves into the ribosome, it very own amino acid is transferred to the growing polypeptide. Once this transfer is complete, the tRNA leaves the ribosome, the ribosome moves one codon length down the mRNA, and a new tRNA enters with its corresponding amino acid, this continues on, and the polypeptides continues to grow.

  1. Termination

Once the mRNA is at a stop codon, this will end the elongation stage. The stop codon doesn’t call for the tRNA, but instead for a protein called a release factor which causes for the entire complex to break part.

 

 

The models accurate reflected the process because my group and I had to go step by step which helped us understand a lot more instead of just looking up online models to copy down. The model cut outs plus the factor of use making the model ourselves gave us a better understanding of what was happening throughout the process. The model we created was very helpful, but it did have its limitations. The models could not include all the small details of the objects that they were supposed to represent. For example, my group and I looked up different steps to confirm we were doing everything correctly and we were concerned that the models we had seen online were typically more complex than the smaller paper model we were working on. I noticed that in the translation process, there were many ribosomes for an mRNA strand which in this activity was no present at any steps. The model was not the best way to represent it as it could no accurate depict all that was going on throughout the process of protein synthesis.