DNA Transcription and Translation
Lesson 6 of 14
Objective: SWBAT identify the primary steps in the processes of transcription and translation.
As the students enter the room, they take out their journals and begin responding to the prompt: What is the purpose and/or function of DNA? While the students work on the journal, I circulate through the room reading their responses. Several of the students had difficulty with this particular journal, so when it was time for volunteers to share their thoughts with the class, there were very few volunteers.
I try shifting gears, and ask the students whether or not DNA is important. They agree that it is important, so I ask them why. The students are able to explain that DNA is genetic material inherited from parents. I ask them to explain why this is important and the specific role DNA plays in the development of traits. The students are then able to articulate that DNA is the code that tells cells which proteins to make.
I ask the students to take out their DNA flipped notes and we review the steps of protein synthesis as well as DNA replication. I have the students add to their notes as necessary and address any questions they have along the way.
After reviewing the basic steps of protein synthesis, I have the students open their Chromebooks and find the DNA Transcription and Translation document in Google Classroom. I review the instructions with the students and then I begin leading them through the first website. I walk students through the slides, step-by-step, to ensure that they hear and see the information. Doing this also provides them with an opportunity to ask questions and allows me to add or clarify information to ensure their understanding. I begin with the general overview of what happens during transcription and translation. Some of the students have a difficult time understanding the concept of transcription, so I try to use analogies to help them better understand. For instance, many of my students have siblings, so I compare DNA's inability to leave the nucleus to being grounded and unable to leave their room. I then compare the mRNA to their sibling or a text message sent to their parents in the hopes of achieving a desired outcome (the creation of a protein). This analogy is flawed, and we review the ways in which this model is and is not similar to transcription. I also lead the students through the translation portion of the activity, paying specific attention to the codons.
One of the reasons for using the websites in this lesson is because they provide students with models of DNA and the translation and transcription process. The students are able to interact with these models to better visualize and understand the processes, as listed in NGSS SP2 - Developing and Using Models. Using the online simulations also addresses the NGSS Cross Cutting Concept Structure and Function 1 as the students use the simulations to create RNA and DNA strands through translation and transcription and view how the bases pair up during the process. The Cross Cutting Concept, Systems and System Models 3, is also addressed as we explore the ways that the simulation differs from how the processes occur within the cells. One basic item that I point out to the students is the use of color and that the colors in the model are not necessarily representative of actual coloration. We also discuss the difference in the amount of time it takes to complete the simulation versus the time it takes for the processes to occur in the cell. This lesson also helps build background necessary for understanding NGSS MS-LS1-2 as we have already reviewed the functions of cells and are now focusing in on the role of DNA in the cell.
This video provides an overview of the websites used during this lesson.
I then have the students continue working through the rest of the simulations on their own. The first item the students complete on their own, is the DNA workshop activity. There are two activities on this website. The first is DNA replication. The students unzip DNA and create complementary strands. The second activity leads students through the process of protein synthesis, a repeat of the information from the activity we completed together during the introduction.
On the next website, the students transcribe and translate a gene. This interactive reviews the information previously covered in the lesson, but requires students to read codons to determine the amino acids necessary to complete a protein.
While the students are working on these activities, I meet with individuals to help them better understand the processes and to gauge their understanding of the concepts. For instance, I will ask a student to explain the step he/she just completed on one of the interactives and ask him/her to tell me whether or not that step is important and to explain why or why not. For example, I may ask a student to explain why they created an RNA strand and why DNA served as the template. I also probe the students' understanding of the information they write down on the worksheet. Some of the students write information word for word from the websites, so I need to make sure that they understand the concepts and ideas behind those words and phrases. Looking at student work, I see that the students understand that chemistry is a part of the process through the role that bonding plays in the development of the amino acid chain. I want the students to have a better understanding that the amino acids have different molecular shapes based on the elements that they contain, so this is something that I make more explicit in a future lesson.
This time also allows me to begin to set the stage for an upcoming lesson on mutations by asking the students if they made any mistakes while trying to create the strand of RNA.
At the end of class, I ask the students to review the steps of transcription and translation. The students are asked to volunteer to describe one step in the process. For instance, I ask the students which process comes first, transcription or translation. I then ask the students why translation is necessary. From there, I ask individuals to describe, in as much detail as possible, the steps of the process. This whole group review provides the students with an opportunity to debrief about the simulations, discuss the processes in their own words, and hear their classmates explain the processes.