Introducing the Process of Protein Synthesis
Lesson 17 of 22
Objective: SWBAT to identify the major steps of protein synthesis: transcription, RNA processing, and translation, and the levels of protein processing
I have found that this introductory lesson is essential for any successful unit exploring protein synthesis. Associating visual images created by experts and creating their own images allows students to form a longer term memory and reference point as we progress deeper into the details of this complicated multi-step process. When I show the video animations of each step of protein synthesis, my goal is not that students remember every detail but rather that they begin to trace the flow of events from DNA-->RNA-->amino acids for themselves so that they can create some prior knowledge for themselves that they can draw from when we start to introduce the many scientific terms and concepts involved with the process.
I will include the video clips that I have found useful over the years--however, you may substitute any of your own that you know work best for your students. The key to successful video clips seems to be length (short and in chunks is always better than long and unseparated by step) and simple animations vs. slick, quick-moving movie style graphics. For some student groups, I have found it more helpful to show the video clips with no sound the first time and then revisit them during lessons later on with the narrative on. This scaffolding keeps the focus on the big picture early on with the details and depth coming in later in the unit. I notice that students ask to watch the videos throughout the unit as they work on their simulation lab and StopMotion video projects and as they review for their exam. I also make the clips available on our school online course management system so that students can access them at home as they review on their own.
I would love to hear more about other video suggestions you have found work for you and your students!
1. Announce to students that today they will begin to explore the process of gene expression called protein synthesis.
2. Write out on the board the three main steps of protein synthesis: transcription, RNA processing, and translation. I also write out the next step of gene expression, protein processing. For each step, indicate the location (nucleus, cytoplasm, ribosome).
- Note: Our class will have already studied the three main types of RNA (mRNA, tRNA, rRNA) and had an assessment on them so I don't review here so that I don't overload them at the start of our unit. I review each individual type of RNA as it comes up during each video clip.
3. Tell students you will be showing them short video clips outlining each phase of protein synthesis. Remind them that the goal today is to observe and listen and to keep referring back to the big picture--the individual phases and the overall purpose. Reassure them that we will go through the details in a variety of ways over the course of the unit and that it is not expected that they will leave the classroom today having a full understanding of each specific aspect of the process. The goal here is for them to begin to incorporate the visuals into their memory banks so that they can refer back to them as we learn more.
- Note: Depending on your students, you may not feel this is necessary to communicate this to your students. For my students, they see the depth of this topic and get a bit nervous and telling them that it is normal for this learning to take time is reassuring to them and allows us to learn together faster and better. Do what you feel is best for your kids!
1. Show the clips for transcription:
Refer back to the board to remind them of the location of the step (nucleus) and the players involved: DNA nucleotides, RNA nucleotides, RNA polymerase. Review the differences between the structure and function of DNA and RNA.
2. Show the clips for RNA processing:
Refer back to the board to remind them of the location of the step (nucleus) and the players involved: RNA pre-transcript, RNA transcript, cap and tail, exons, introns, sNURPs/spliceosomes.
- Note: The emphasis here for me is on creating visuals rather than deep, detailed understanding and descriptions. Use pipe cleaners to show the work of sNURPs to cut out introns and put together exons. I also tell students we will be doing more work on the idea of exons and introns later. Students are curious about the idea of DNA/RNA code that is unnecessary for protein synthesis/gene expression, which is great! At the same time, there are a lot of moving parts for this process and I find it is better to wait until later so that the students don't get overloaded right away).
3. Show the clips for translation:
Refer back to the board to remind them of the location of the step (cytoplasm/ribosome) and the players involved: ribosomal subunits (large and small), A-P-E sites, mRNA, tRNA, amino acids, peptide bonds, rRNA.
- Note: I keep this step discussion as simple as possible. I use clay to show the two ribosomal subunits and how they close around the mRNA transcript (a pipe cleaner).
4. Show the clips for protein processing/folding:
Refer back to the board to remind them of the location of the step (cytoplasm/golgi body) and the players involved: amino acids, primary-secondary-tertiary-quaternary levels, polypeptide vs. protein.
- Note: Once we have finished the videos, I pass out a summary of gene expression for additional student support. I also refer them to our complete slide presentation for the entire DNA and protein synthesis unit further review at home.
- I have found some students prefer concept maps for review and support. I use the website www.popplet.com for this, both for student use and my own. Below you will find the ones I have created for this unit:
1. Congratulate students on their attention and engagement so far!
- Note: This is tough stuff! I like to remind them that right now they know more about genes, DNA, and protein synthesis than any adult they know.
2. Tell students that they will be working in pairs to create a diagram of the process of protein synthesis (transcription, RNA processing, and translation) and protein processing. Pass out the Protein Synthesis Introductory Activity document and point out the specific tasks to complete as a team.
- Note: If specific student groups need additional support, consider having students break up the work within their group of four, one piece of the overall flow for each student in the group. Whenever possible, however, I suggest having student pairs work together to dig deeper into the entire flow of gene expression rather than dividing up the work into four parts. At times that means having students pick partners rather than work in their assigned lab pairings and I make that decision on a class-by-class basis.
3. Point out where student teams can find large drawing paper, colored pencils, rulers, and any other supplies available in the classroom for the students to use (markers, highlighters, colored paper, sticky notes, etc.).
- Note: I have found that using large drawing paper (11 x 14 or cutting out butcher paper sheets by hand) is better than using the typical 8.5 x 11 printer paper. Kids really need to think expansively to get their thoughts down and visualize the entire process as a whole. Doing so now will really help as they start to add in specific details and terms into their individual understanding and memory over the course of the unit.
4. As students work, observe progress without intervening right away whenever possible and appropriate for the individual student groups. This is their time to start to wrestle with challenging material with their partner--more direct instruction opportunities are coming, I promise!
5. As the class period comes to a close, remind students that there will be addition time in class the following day to complete their team drawings with narrative. This work should be messy, not presentation quality. The idea here is for students to think out things in a non-linear way that can be shaped into something more sequential as we add more levels of understanding and experience with protein synthesis concepts throughout the unit. Check out this student work sample for an idea of what you can expect from your students. It isn't about what the work looks like to you and I but rather, what it means about what students are thinking about protein synthesis. What I can see here is a decent understanding about locations and transcription and RNA processing as well as the basics of protein folding. Where this student pair needs time and support is on the trickiest step, translation. That should be what you see on many drawings. This is our first day with the content and I know this will shift over time to include more details and an increase in use of relevant scientific terminology.
- Note: Alternatively, you can assign it for out of class time with a later turn-in deadline. I prefer to utilize class time so that I can hear the questions students are exploring together and tailor my remarks the next day to ensure that they are addressed.
For additional/future support as students navigate the many steps of protein synthesis, I provide this Protein Synthesis check-in document to help students sequence and remember the steps in a more linear way. Here is the Protein Synthesis check-in document with sample answers. I keep this in the classroom for students to use as they compare their own work with my way of describing the steps of protein synthesis. In other years, I have simply copied it for every student but found that it gets tucked away into a far away space deep inside messy backpacks never to be seen or thought about again. Keeping it in the room creates a bit of a sense of urgency for students to attempt the work on their own in order to get access to the master document and since I am present, we can have a very casual but productive conversation directly tied into the needs of individual students at that moment in their learning pathway.