RNA is a polynucleotide like DNA, and its made out of a chain of nucleotides. However, some unique traits RNA has is it’s single stranded and short, contains the sugar ribose, and has a pyrimidine uracil replacing DNA’s thymine. RNA’s job is to convert DNA’s message and output a protein. Messenger RNA, ribosomal RNA, and transfer RNA are the three types of RNA involved in protein synthesis. Looking into the messenger RNA, the DNA transcripts its message onto a messenger RNA and later it will be translated by a ribosome to produce the protein. In the transcription stage, a specific section of DNA unwinds and exposes one gene so that along one strand, RNA bases can bond with the DNA bases. Then adjacent nucleotides form covalent bonds and build a RNA backbone while the RNA polymerase facilitates the whole process. This process is shown in image 1 as the long white paper with printed ink represents the DNA strand and the long white paper with pencil ink represents the complimentary base pairing occurring. Model 2-4 also shows the process of transcription as image 2 shows the unwinding and breaking of the hydrogen bonds, image 3 shows the complimentary base pairing happening with the help of RNA polymerase (represented by the purple Play-Doh), and finally the separation from the DNA in image 4. This model is good at representing the main steps that occurs in transcription, but it some flaws are that the models only show the section of the gene and not the whole DNA which may be misleading.

 

 

Image 1  Image 2     Image 3

Image 4

After the messenger RNA arrives at the ribosome, the translation process begins which when messenger RNA is converted into a polypeptide. There are three stages in the translation process, which are initiation, elongation, and termination. In initiation, the messenger RNA gets held by the ribosome and the P-site in the ribosome reads the start codon AUG and brings the matching transfer RNA brings the amino acid. The transfer RNA has a complimentary three letter code called anticodon which identifies the amino acid needed. A codon are three letters on messenger RNA. This is shown in image 5 as the ribosome grabs on to the messenger RNA and the transfer RNA bring the first amino acid after reading the starting codon labeled on the white paper (note the paper with the printed letters is the strands of DNA and should not be included in the photo). In elongation, the amino acid chain continues to grow as other transfer RNA binds to the A site. The transfer RNA in the P site lets go of the amino acid and leaves the ribosome allowing new transfer RNA to come in. In image 6, the model shows the transfer RNA leaving the amino acid behind with the new transfer RNA in the A site that has another amino acid to add to the chain. In image 7, it shows a new transfer RNA with an amino acid entering the A site. Finally in termination, the whole process ends when the “STOP” codon is read, which is a three letter word that does not have matching transfer RNA. This means no new amino acid is added to the chain and everything releases from each other. In image 8, the messenger RNA reads the stop codon and the complete chain of amino acids is shown. Then in image 9, the polypeptide is released and the ribosome dissociates to two subunits. The activity did a good job modeling the simple process of the amino acids building up as the transfer RNA brought in more amino acids according to the messenger RNA. However, the model was inaccurate as it was hard to show the transfer RNA reading each codon in the messenger RNA.

Image 5 Image 6Image 7 Image 8Image 9