Living beings are made up of cells, which conduct many functions that help in sustaining a healthy and normal life. One of the most important functions of the cell is called protein synthesis. This is done with the help of hereditary material - DNA and RNA. Both are made up of nucleic acids, and they play an important role in transferring genetic information from one generation to the other. The protein synthesis process can be divided into two important processes: transcription and translation. Both of them are done inside the cell, but they take place at different places.
Where Does Transcription Happen in a Eukaryotic Cell
Transcription is a process in which the DNA is transcribed into mRNA. This is a very important part of the protein synthesis process. Eukaryotic cells are facilitated with the nucleus, and they can have one or more nucleus, which contains the genetic materials such as DNA and RNA. These materials actively participate in the process of protein synthesis, which takes place inside the nucleus, and subsequently, mRNA is formed. Then the transcribed mRNA comes out of the nucleus pores into the cytoplasm. The translation takes place, and thus, completes the process of protein synthesis.
This process is initiated when the DNA molecule uncoils its strands by breaking the hydrogen bonds, which hold the complementary base pairs together. When the strand uncoils, one of its parts behaves as a template for the production of mRNA, and is known as anti-sense strand. The other leftover part is the sense strand. Then RNA polymerase enzyme, which has the sigma factor recognizes the DNA template. The complementary ribonucleotides are attracted towards it, and arrange themselves opposite to the template, and also to their specific sites. Only thymine is replaced by uracil in the RNA molecule (the only difference in the RNA and DNA coding). Once the molecule is completed, it detaches itself from the DNA, and rest of the DNA strands attach again with the help of a hydrogen bond. The newly formed RNA molecules contain messages for protein synthesis, hence known as mRNA or messenger RNA molecules. This molecule goes out of the nuclear membrane, and then the remaining process of protein synthesis, which consists of DNA translation is completed.
Where Does Transcription Occur in a Prokaryotic Cell
Prokaryotic cells are the primitive ones that lack a nucleus. This is the reason why the entire process of protein synthesis in such cells takes place in the cytoplasm. The transcription and translation is done alongside simultaneously. The process is nearly the same as in eukaryotes, but the only difference is the location where it takes place. The eukaryotes have a membrane bound nucleus. Hence, the ribosomes do not reach the mRNA to carry on the translation process. But in the prokaryotes, the ribosome is easily available in the cytoplasm, and hence, both the processes take place simultaneously.
Transcription process in prokaryotes can be divided into three stages - initiation, elongation, and termination. In initiation, the RNA polymerase binds to the sigma factor to form holoenzyme. This enzyme recognizes the promoter region in the DNA to form a closed complex. The RNA then starts proceeding towards the elongation stage. Thus, the RNA transcript increases in length. Then finally, in the termination stage, the RNA polymerase pauses, and the mRNA molecule is terminated from the DNA molecule.
Protein synthesis is an important function of the cell, and hence, an important part of DNA research and studies.