Protein Synthesis, part 3
Lesson 7 of 16
Objective: Students will engage in a number of review activities that will strengthen their understanding of the process of protein synthesis before taking a summative assessment.
Warm-Up: Where does transcription take place and what is its product? Where does translation take place and what is its product?
Ask this question as a quick formative assessment to determine if students met the learning targets from the previous lessons (Protein Synthesis, part 1 and Protein Synthesis Lab) that introduced and reinforced the process of protein synthesis. Listen and note any misconceptions about what occurs during transcription and translation. Assess how easily students are able identify that mRNA is the product of transcription and proteins are the product of translation. Use the first questions to build students' critical thinking by asking secondary questions that will help assess the depth of understanding of the students. For example, ask students, “Why does transcription occur in the nucleus?” Allow students to engage in academic discourse, using the academic sentence prompts. Give students ample opportunity to correct one another through discourse before offering the correct answer to an incorrect student response. For example, “Do you agree with that response?” “Tell me why or why not.”
Distribute copies of a graphic organizer. Display the same organizer on a LCD projector. Instruct students to take 8 minutes to complete as many parts of the graphic organizer as they can without using their notes. Allow them to work with a seat partner to complete the task. Set the timer and display it so that students will be able to monitor their progress.
Walk around the room and listen to the conversations at the tables. Do not provide any feedback or guidance at this time. Note the parts of the organizer that appear to be difficult for students to complete so that you can conduct a spiral review of those concepts when you go over the organizer at the end of the timed period.
At the end of the designated time, stop students from working and instruct them to turn their attention to the LCD projector. Work through the organizer by writing the correct answer in each space using a digital pen and pad. Allow students to offer answers. However, be sure to model the thinking associated with each correct response using the “think aloud” modeling strategy. This will allow students to observe your reasoning and processing skills for completing the organizer.
Ask students to consider how easily it was for them to complete the organizer without your guidance so that students will reflect on how much of the content they know. Encourage students to use the self-reflection to determine how prepared they are for the assessment, Make sure that students understand that their ability or inability to complete the organizer should help them determine what actions they need to take to prepare for the assessment.
Inform students that they will now engage in a foldable activity that will allow them to review the process of protein synthesis.
Distribute copies of a protein synthesis foldable and markers. Provide both verbal and written paper fold instructions using a LCD projector for the different learner types. Because the folding of the paper may be difficult for some, it may be useful to pre-fold the paper before distributing the templates so that folding of the paper correctly does not impede the completion of the activity.
Note: I added a "How to fold the paper" video for details on the correct way to fold the paper. Practice folding the paper before showing students how to perform the paper fold.
Write the DNA template that is displayed on the board on the folded paper. Explain that there are 4 steps of the foldable activity:
Using the “think aloud” strategy, model how students will complete the replication portion of the foldable, using the Base-Pair Rule. Complete the DNA replication base pairing for the first 3-4 nitrogen bases then release students to complete the remaining base pairing on their own. Walk around to monitor that all students are on task and able to apply the complementary DNA base pair rule. Narrate how students will open the paper to model how DNA unwinds with the help of helicase. Instruct students to again use the DNA base pair rule to identify the complementary base for each of the exposed sides of the template strand. Point out that students now have 2 exact replicas of the original template strand. Ask students what word best fits the blank: DNA replication produces a(n)__ copy of the original strand.
Instruct students to refold the paper to its original state. Instruct students to turn their attention to the part of the foldable that says, Step 2 Transcription, mRNA. Again, use the think aloud” strategy to model how students will complete the transcription step of the foldable, using the RNA Base-Pair Rule and the original DNA template strand. Complete the RNA base pairing for the first 3-4 nitrogen bases then release students to complete the remaining base pairing on their own. Walk around to monitor that all students are on task and able to apply the complementary RNA base pair rule.
Instruct students to turn the paper over so that step 2, step 3 and step 4 are all visible. Make sure students open the paper completely so that step 4 is visible. Instruct students to turn their attention to the part of the foldable that says, Step 3 Translation, tRNA. Again, use the think aloud” strategy to model how students will complete the transcription step of the foldable, using the RNA Base-Pair Rule and the mRNA strand. Complete the RNA base pairing for the first 3-4 nitrogen bases then release students to complete the remaining base pairing on their own. Walk around to monitor that all students are on task and able to apply the complementary RNA base pair rule. Ask questions as you monitor students’ work, “What is another name for tRNA?” Or “What is another name for codon?” Point out the DMRTAP” letters indicated with step 3. Ask students what they think those letters mean. Look for students to indicate that those letters will help them recall the steps of protein synthesis. Ask if they can recall the pneumonic you gave them in lesson, Protein Synthesis, part 2 to help them learn the steps of protein synthesis.
Instruct students to turn their attention to the part of the foldable that says, Step 4, Amino Acids linked into proteins. Again, use the think aloud” strategy to model how students will identify the amino acid that corresponds to each codon from the mRNA strand. Identify the first amino acid then release students to identify the remaining amino acids on their own. Walk around to monitor that all students are on task and able to use the mRNA decoder sheets to find the correct amino acids on their own. Ask questions as you monitor students’ work. Ask, “What type of bonds hold the amino acids together?” or Why do we also call proteins polypeptides?”
After guiding students through this foldable activity, explain that the intent is that can use the foldable as a review tool at home. Encourage students use this foldable as a review tool by narrating and performing each of the steps at home.
Display a Protein Synthesis tiered activity and distribute hard copies of the activity in sheet protectors for repeated use. Explain that this is a cumulative review activity in which students are expected to select one activity from each of the 3 categories (DNA/RNA, Transcription, and Translation).
Instruct students to follow the instructions and use the rubric to help them complete each assignment. Display the rubric and summarize the criteria associated with the scoring. Show students how they can select any (1) activity in row one, any (1) activity in row two and any (1) activity in row three. Emphasize that any combination is acceptable as long as students do not complete more than one activity per row, which means they will submit three different activities form three different categories.
Walk around to monitor that all students are on task and able to complete the assignment.
The value of a tiered assignment is that it allows students to select the activities that interest them. Student 1 chose to draw and label both DNA and RNA molecules, create a flowchart and write a poem about the process of protein synthesis. Student 2 chose different activities, including writing a paragraph explaining the differences between DNA and RNA, writing a script and creating a flowchart. Student 3 chose to draw a picture, write a TV talk show script and create a flow chart. While the work prodcuts are different, each allowed students to select various ways to show their understanding of the content, while at the same time deepening their understanding and preparing for a summative assessment.
Close the lesson with a recap of the major points about protein synthesis. Emphasize the value of students spending time reviewing the notes before the summative assessment.
Ask students to differentiate between transcription and translation. Look for students to be able to explain that transcription occurs in the nucleus and that translation occurs on the ribosomes.