What Is Protein Synthesis?
So what does protein synthesis mean? Most people just know it as something to do with building muscle. Since we discussed Amino Acids previously, this topic goes along with it. Protein not only builds muscle and other tissues, its involved in our hair, skin, nails, and making hormones and enzymes.
“Building a house is a good analogy for protein synthesis. The DNA would be the architect, who has the plans for the whole house. The DNA is changed into mRNA, which is like the copy of the blueprint given to the general contractor." (study.com).
Protein synthesis is the process our bodies go through to make the proteins we need from the foods we consume. Without this process the body will not have the protein it needs. Protein is essential to all of our cells structures and functions.
The first step in Protein Synthesis is transcription, which is the transfer of DNA to mRNA. This process begins when the enzyme RNA binds to a part of a gene. This signals the DNA to unwind so the enzyme can “read” the DNA. This results in 2 strands developing. The strand that is used as a template is called the template strand. The opposite strand of DNA is called the sense strand. Once the DNA has opened, and RNA has attached, the RNA moves along the DNA, adding RNA nucleotides to the growing mRNA strand. The template strand of DNA (the one mentioned that will be used) creates mRNA through complementary base pairing. Once the mRNA strand is complete, it then detaches from DNA. The result is a strand of mRNA that is nearly identical to the template strand DNA…
At this point the mRNA is still not quite ready to be released and must be classified as ‘mature mRNA’ before it can leave the nucleus and be used to make protein. Various processes modify the mRNA as it is needed. Modifications like splicing, editing, and polyadenylation allow a single gene to be used to make more than one protein.
After this process there is one more referred to as “Translation” which happens in 3 stages: Initiation, Elongation and Termination.
After transcription is complete the mRNA moves from the nucleus and enters a ribosome, located in the cytoplasm. As it enters the cytoplasm, (the liquid that fills a cell) there is a specific cap on the mRNA that will bind to the ribosome, this is then met with something called tRNA to form an “initiation complex”.
For elongation, the last part of the process, the tRNA keeps providing amino acids to the growing polypeptide according to the base pairing between the mRNA and the tRNA. Polypeptide meaning what is being created by this process.. “a linear organic polymer consisting of a large number of amino-acid residues bonded together in a chain, forming part of (or the whole of) a protein molecule”. As a tRNA moves into the ribosome, its amino acid is transferred to the growing polypeptide. Once this transfer is all done, the tRNA leaves the ribosome. The same ribosome moves one codon length down the mRNA, and a new tRNA enters with its amino acid. This process repeats and the polypeptide continues to grow…
At the end is a stop codon which will end the elongation stage. The stop codon doesn’t call for a tRNA this time, but instead for a specific protein called a release factor, which will cause the entire complex to break apart and release all of its parts!
After a polypeptide chain is synthesized, it may undergo additional processing to form the finished protein… but majority of the work is done. For example, it may form into a folded shape due to the interactions between its amino acids. It may also bind with other polypeptides or other types of molecules, such as lipids (fats) or carbohydrates. Most proteins travel to the Golgi apparatus, also within the cytoplasm of the cell, to be modified for the specific job they will do for us.
Hope that helps,
Happy EATING!
Robyn :)
https://humanbiology.pressbooks.tru.ca/chapter/5-6-protein-synthesis/
https://flexbooks.ck12.org/cbook/ck-12-college-human-biology-flexbook-2.0/section/5.6/primary/lesson/protein-synthesis-chumbio/