As promised in my last blog, here is the first section of my Independent Research and Design (IRaD) final research paper. This part of my paper provides the details of DNA transcription and translation explaining the basics of our genetic makeup. It is important to understand the structure and function of DNA before diving too deep in the study of Down’s syndrome because Down’s syndrome is a genetic disease and is caused by a mutation in the DNA structure.
At the beginning of the academic year, I learned about DNA’s double helix and the formation of adenine, guanine, cytosine, and thymine. Together, these four monomers create a specific order within the DNA strand and are held together by a chemically bonded sugar-phosphate backbone. This bond is much stronger than the hydrogen bond that hold the two strands of a double helix together, which is very important because the DNA strand is in a very specific order—although it can be ordered various ways depending on the person—and needs to stay in the specific order it starts in at all times4.
DNA strands are used to produce proteins through a process using different types of RNA, each with different jobs. The three different types of RNA make the transcription and translation process happen. The first is the messenger RNA, mRNA, which is used to make “copies” of small segments of DNA. Ribosomal RNA, rRNA, reads the mRNA copy and makes the protein that it codes for. The last is the transfer RNA, tRNA, which brings an amino acid needed to make the proper protein to the scene, bringing the whole process together2,4,8, 9*.
Transcription, which takes place in the nucleus, is initiated when RNA polymerase attaches to the promoter and opens the DNA, beginning to match RNA nucleotides to the template strand. Next, it is continued to be elongated in the elongation phase and the mRNA peels away from the DNA strand. Finally, the process reaches termination when the polymerase gets to the stop message. When this happens, the mRNA copy comes off and the RNA strand closes. The mRNA is a copy of the DNA strand where thymine is replaced by uracil. The point of transcription is to create an mRNA copy of the DNA strand in order to use it to make a protein on the ribosome2,4, 8, 9.
Translation follows similar steps to transcription but starts where transcription left off. The initiation is with tRNA when it attaches with the RNA strand as AUG, the start codon. The tRNA has an anti-codon at the bottom of its T shaped structure that will match the mRNA code that it attaches with and has an amino acid on the top of it. As the tRNAs attach the amino acids on top create a long chain of amino acids that is in direct relation to the original DNA strand. The amino acids combine to become the proteins that the gene stands for2, 4, 8, 9.
*All the citations are listed in the bibliography that can be found in the documents section of my blog.
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