After wrapping up the discussion from the previous day’s lesson, we launched into an investigation of the process of Central Dogma. Students learned how DNA codes for RNA which codes for protein. We drew out the processes of transcription and translation, using a guided worksheet approach to help students understand what happens at each step of the process. Whiteboard notes from two different classes are shown below:
Updated: February 5, 2016
We completed the DNA base-pairing worksheet that we began yesterday. We reviewed how DNA codes for RNA and RNA codes for protein. We learned how RNA is read by ribosomes, with 3-base RNA sequences (codons) coding for specific amino acids. Students were surprised to learn that that for many amino acids, there are more than one codons. This was emphasized in questions 22 and 23 of the worksheet, where students learned to work backwards from a sequence of amino acids to figuring out one possible RNA sequence encoding that amino acid sequence, and finally figuring out the DNA sequence coding for the chosen RNA sequence.
Question 26 of the worksheet asked students to notice how amino acids with multiple codons often “wobble” at the third position (click here for a brief summary, or here for a not-so-brief summary). The picture below attempts to add some context to the discussion.
With all of the HHS science teaching staff participating in a Studio Day, students were tasked with completing a DNA base pairing worksheet with guidance from a substitute teacher. Students learned that in complementary DNA strands, A pairs with T and C pairs with G. When RNA is transcribed from DNA, the rules are the same with one exception: mRNA uses U instead of T, so in a DNA:RNA pairing, the A in DNA pairs with U in RNA. Students went on to learn about codons (adjacent sets of 3 RNA bases) and learned how codons code for amino acids. Students learned how to write the 3-letter and 1-letter amino acid abbreviations, and solved the amino acid structure from a DNA strand, as well as solved a DNA strand from a short amino acid sequence.
We began class with a new seating chart. Students organized themselves by birth month and were seated in pairs. Students were reminded how important it is to make new friends and engage with new people to learn new ideas and ways of approaching a scientific challenge.
After the seating chart, students were provided with a timeline for making up work from the last two weeks of Unit 4. All late work and revisions are due by this Friday. Students were also reminded to check in on the class website daily and to monitor the new Twitter feed for interesting science articles.
Next, we launched in to Unit 5: Central Dogma. Students were asked to write down everything they know about DNA and then shared their knowledge with their new table partner. Students were encouraged to use the agree/disagree structured partner talk strategy. Student pairs then shared one piece of information about DNA that they discussed by writing it on a class white board. An example of the information from one class is given below.
Finally, students received a few slides of instruction regarding Central Dogma vocabulary before we watched the first 16 minutes of Cosmos: Episode 2. The last slide of the lesson lists the questions students answered while watching the video.
On Wednesday, we kicked off the Evolution unit with our first lesson. In Lesson 1, students watched a video about the evolution of soccer and then brainstormed other everyday things that have evolved over time. Student ideas included the evolution of vehicles, animals, society, technology, and medicine. In the lesson, students learned that DNA can change through missense mutations, nonsense mutations, and frameshift mutations. After the lesson, students worked with a partner to investigate a hypothetical scenario requiring the integration of research skills, critical reading skills, recollection of the Central Dogma, and application of DNA mutations. The investigation will conclude on Monday. By the end of class Thursday, most students had successfully answered questions 2-6 of the worksheet. As the events of 1995 and 2000 were before many of the students were born, we watched the following videos to bring closure to that part of the investigation and to introduce students to part of Seattle cultural history.
Picking up where we left off before Task Week, in Lesson 5 we reviewed key vocabulary related to the Central Dogma. Students received blank copies of the vocabulary worksheet and were provided with time in class to transcribe Central Dogma-related definitions. The remainder of the class period was spent working in small groups to discuss and debate whether specific traits are inherited through nature or nurture. The purpose of this lesson was to provide students with a link between proteins (encoded by genes within DNA) and phenotype (traits that are readily observed). Next, we will turn our attention to how traits are inherited: mitosis and meiosis.
What a week! I am so proud of my students for staying on track and doing an outstanding job presenting their DNA Replication projects to the class. Students who did not present this week are expected to present at the beginning of class on Tuesday. Today we learned about the Central Dogma concept (Lesson 4). We explored how introns are excised from mRNA by the spliceosome and the resulting mRNA exits the nucleus and is translated into protein by a ribosome. Students received a set of notes to use for review and which should be very helpful in completing the Central Dogma Crossword Puzzle. The crossword puzzle is due next Thursday (January 30). Students who would like to extend their learning about introns should consider reading “New Genes Spring, Spread from Non-Coding DNA” and share your learning with the class!
This lesson is all about the Central Dogma: DNA makes RNA makes protein. Review the lesson (Genetics Unit Lesson 3) and complete the worksheet (DNA_base_pairing activity) to demonstrate mastery of this challenging concept. Remember: Monday is the Martin Luther King, Jr. holiday so we will not have school until Tuesday. You will have the weekend and all day in class to complete your DNA Replication projects. Use your time wisely! Be ready to present your learning to the class. Groups will have at least 5 minutes to share their work and answer questions. Also, the Biology Task Golden Ticket deadline has been extended to February 14. Upload your drafts to Ms. H’s Dropbox folder or email them directly to me for feedback.