Transcription
Concept Development
Before jumping into the process of Transcription, it is a good idea to give your students a big picture of protein synthesis as a whole by going over the Central Dogma of Molecular Biology. I would also recommend that you ensure you go over the difference between DNA and RNA, as well as the different types of RNA as these aspects will come into play throughout the process of protein synthesis.
When it actually comes time to introduce transcription to your students, you should explain to them that you are looking at the first step in the Central Dogma in which DNA is being transcribed into mRNA. To explain the process of transcription, it is suggested that you begin by using stationary images to explain the steps. After you have gone over the steps using stationary images, you can then reinforce the steps through other methods such as activities, interactive games or animations.
When explaining the process of transcription there are 3 main steps:
Additional Terminology:
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It is important to realize that there is a difference in the timing of the steps of protein synthesis when comparing prokaryotes to eukaryotes. In prokaryotes, transcription and translation can be occurring at the same time since these organisms lack a nucleus. On the other hand, the mRNA in eukaryotes must leave the nucleus before it can be translated by the ribosomes that are located in the cytoplasm. However, before the mRNA can leave the nucleus to be translated there are a few post-transcriptional modifications that must occur.
Modifications:
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Misconceptions
When covering the process of transcription, it is easy for students to make mistakes when it comes to the terminology involved. It is for this reason that we as teachers must ensure we are using the proper terminology when we are teaching these concepts to our students. Some common errors that teachers should be aware of when teaching the process of transcription are:
- Students may think that the coding strand is the DNA strand that is used to build the complimentary mRNA strand when in fact it is the template strand that the RNA polymerase binds to to make mRNA.
- Students will often say that DNA is used to create RNA which is then translated into a protein. However, it is important that you go over with your students that there are different types of RNA and thus the correct terminology is that our DNA is transcribed to create mRNA.
- Students may pair Adenine with Thymine when they are creating the complimentary mRNA sequence. This issue can be addressed by going over the difference between DNA and RNA with your students before moving on to introduce the topic of transcription. By doing this, you can inform your students that Thymine is replaced with Uracil within RNA.
- During the post-transcriptional modification process, exons and introns will probably cause some confusion for your students. Often times your students will assume that the exons will be spliced out and the introns will stay, when in fact it is the opposite. Since this will be a common mistake that many of your students will make, ensure you go over this a few times with your students and remind them that introns are the sections being removed.