Teaching the Concept of Protein Synthesis Rebecca Lostracco Jacqueline McCann

Introduction to Protein Synthesis If you asked any body builder, they would tell you that muscles are built from protein. But have they ever wondered how proteins are actually made in our body? It all starts with one thing: DNA! Now you just create protein from DNA. Sounds simple, right? Wrong! To understand this concept, you’ll need to learn about the central dogma of transcription and translation. Really, really Important!!

Lesson Sequence Lesson 1: Protein Synthesis: An Overview  The Central Dogma, RNA, The Genetic Code Lesson 2: Transcription  Initiation, Elongation, Termination Lesson 3: Translation  The Ribosome, Transfer RNA, Elongation of the Polypeptide Chain, Termination Lesson 4: Control Mechanisms  The lac Operon, the trp Operon Lesson 5: Mutations  Types of Mutation, Causes of Mutation Lesson 6: Differences Between Eukaryotes and Prokaryotes

Curriculum Expectations D2.4 investigate and analyse the cell components involved in the process of protein synthesis, using appropriate laboratory equipment and techniques, or a computer simulation D3.2 compare the structures and functions of RNA and DNA, and explain their roles in the process of protein synthesis D3.3 explain the steps involved in the process of protein synthesis and how genetic expression is controlled in prokaryotes and eukaryotes by regulatory proteins (e.g., the role of operons in prokaryotic cells; the mechanism of gene expression in eukaryotic cells)

The Central Dogma: Teaching Approach Video demonstration of Protein Synthesis

The Central Dogma: Teaching Approach Protein Synthesis Virtual Lab  Students use an inquiry-based approach to transcribe a DNA molecule into RNA, and then translate the mRNA into a protein  Students interactively learn more about transcription and translation Transcription and Translation Virtual Lab

The Central Dogma: Teaching Approach Protein Synthesis Role-Play  Teacher ropes off a designated area as the nucleus where transcription must occur. The rest of the classroom is the cytoplasm where translation will occur.  8 students are assigned to DNA sequences (24 nucleotides in each)  8 students are assigned to complementary mRNA sequences  8 students are assigned to complementary tRNA anticodons with corresponding amino acids (polypeptide chain)  8 special learning opportunity messages (Ex. “Ribosomes move along the mRNA in a 5’ to 3’ direction, while reading the coding sequence.”) are posted around the classroom corresponding to amino acid polypeptide chains

The Central Dogma: Teaching Approach Protein Synthesis Role Play Continued  DNA students and mRNA students remain in nucleus during transcription. After transcription, mRNA students move into cytoplasm, where tRNA students are waiting for translation.  DNA students begin by writing down the complimentary RNA sequence to their DNA sequence (transcription). They then search the nucleus for their matching mRNA student.  mRNA student then leaves the nucleus and uses the genetic code to write down the corresponding amino acids to their RNA sequence (translation). They then search the cytoplasm for their matching tRNA student.  The tRNA student then searches for the special message associated with their polypeptide chain, thus completing the task.

Potential Student Difficulties Abstract concept – may be hard for students to picture Remembering that in RNA, Thymine is replaced with Uracil Recognizing the matches between nucleotide bases and amino acids (i.e., using the genetic code table) Distinguishing between DNA and RNA as well as between the roles of mRNA and tRNA  mRNA carries coded DNA message  tRNA carries amino acids Recognizing a stop codon which signals for translation to end Only 2 tRNA molecules can attach to the ribosome at a time Polypeptide chain is transferred from one tRNA to the other before tRNA leaves the ribosome

Solutions to Student Difficulties Role-play activity will help to make concept more concrete Students can make their own mnemonics for remembering stop codons (UAU, UAG, UGA) Having an anchor chart with nucleotide bases and their corresponding amino acids During role-play activity, emphasize the distinction between mRNA and tRNA by having the students in those groups wear a label Create a T-Chart/Venn Diagram to compare roles of DNA & RNA and mRNA & tRNA Model translation in role-play activity slowly and clearly for the students Have students proceed step-by-step, explaining their role in the process

Safety Considerations This unit includes a virtual lab, which makes the main safety concern appropriate internet conduct To safely implement the role-play activity, the classroom will need to be free from clutter with space for students to move around Students will be given explicit instructions on the role play activity so they are aware of the expectations how to execute their role

Practical Applications “What makes a Firefly Glow?” demonstration of how protein synthesis is involved in making a firefly glow Foods and Protein Synthesis examples of foods that increase protein synthesis to support muscle building Exercise and Protein Synthesis discuss the rate of protein synthesis in relation to exercise

Differentiated Assessment Students would have a choice for their culminating task assessment on protein synthesis. The following tasks are targeted to students’ multiple intelligences:  A poster displaying the process of protein synthesis (Visual)  A song about the concept of protein synthesis (Musical)  A 3-D model showing the main “players” in protein synthesis (Kinesthetic)  A videotaped oral story about the process of protein synthesis (Linguistic)  A journal entry on what they learned about protein synthesis (Intrapersonal)  A lesson on protein synthesis that is taught to the class (Interpersonal)  A lab activity involving transcription of provided DNA nucleotide sequences into mRNA, splicing of the mRNA, and translation of the mRNA into a protein (Logical) Students’ understanding of the concepts of protein synthesis would also be evaluated on a unit test Formative assessment would be completed based on students’ contributions to class discussions during role-play and participation in the online lab