The Central Dogma (#4 of 6): Transcription

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Objective

Systems of specialized cells within organisms help them perform the essential functions of life. (HS-LS1-1) All cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells. (HS-LS1-1 & HS-LS3-1)

Big Idea

The structure of DNA is a double helix. Its shape explains how hereditary information is stored and passed along to offspring.

Learner Goals

Note: I recommend that you first check out this resource in order to get the most out of this lesson!

In high school I took several drafting classes and, for a while, I had hoped to become an architect. With respect to planning instruction and teaching, I feel that I can still live out the detailed approach to building something intricate and complex even though the product is a lesson rather than a certain "built environment".

The lesson-planning document that I uploaded to this section is a comprehensive overview of how I approach lesson planning. This template includes the "Big Three" aspects of the NGSS standards: Disciplinary Core Ideas, Crosscutting Concepts, and Science Practices. Of course, there are many other worthy learning goals, skills, instructional strategies, and assessments that can be integrated into a class session. I don't feel compelled to check every box but, rather, use it as a guide to consider various options and tailor the lesson in light of these.

With regard to this particular lesson, students will:

1. understand that cells store and use genetic information to guide their functions. Furthermore, the structure of DNA is a double-helix. Its shape explains how hereditary information is stored and passed along to offspring.

2.  know that all cells contain genetic information in the form of DNA molecules. Genes are regions in the DNA that contain the instructions that code for the formation of proteins, which carry out most of the work of cells. (HS-LS1-1 & HS-LS3-1)

From the perspective of instructional strategies, I want to emphasize the following challenges:

Teaching Challenge: How do I support students to develop and use scientific models

I hope you get some value from my work!

Anticipatory Set ("Hook")

10 minutes

Click here for the previous lesson in the series.

Peer Instruction Protocol (PIP): Leveraging an individual and group-oriented review strategy.

The previous two days of instruction focused on the structure and function of genetic material (DNA and RNA) and the mechanism and purpose of DNA replication. At this point I want to reflect on whether students learned what I intended. I regularly make use of the PIP review strategy as a way to assess student learning. A more detailed explanation is provided here.

I will progress through this review activity in stages and following each major topic taught in the near past. In this case, I will address only questions #4-6 (Replication).

Please see how this looks in the class as shown in the following two class photos: Class PIP #1 and  Class PIP #2

Instructional Input/Student Activities

20 minutes

Central Dogma Notes (slides #10-12)

In this segment of the lesson, I spend some time using the strategy of direct instruction using the Cornell note-taking method. The topic is DNA replication and the context is to compare and contrast mitosis with meiosis (previously studied in this series).

Teaching Challenge: How do I support students to develop and use scientific models?

Students should recognize that the model of the double-helix structure allows for the pairing of  DNA strands with its complementary RNA partner during transcription.This is what made Watson and Crick's discovery (description) of the form of the DNA molecule so incredible because the shape beget the process: unzip along the middle, match complementary bases (owed to Erwin Chargaff's work), release of the mRNA, with DNA zipping back up when its all over. Its elegance is in its simplicity!

In essence, students should recognize that the relationship between chemical bases on both DNA and RNA nucleotides is that they are complementary for both the DNA-DNA relationship (replication) and DNA-mRNA relationship (transcription), and mRNA-tRNA relationship (translation). By knowing the rules for base-pairing (pattern) students will be able to predict the complementary copy of either DNA or RNA. The question of how the (DNA) genotype morphs into the (protein) phenotype is largely explained by this simple relationship!

Closure: What did we learn? Where do we go from here?

25 minutes

Central Dogma Review

As we wrap up for today, I direct students to complete remainder of p. 1 ("translation" questions only) to apply what they learned. This review packet will be completed in several stages as we progress through this lesson series. 

The answer key is provided for your reference.

Click here for the next lesson in the series.

Lesson Extension & Follow-Up Activities

Students will be directed to finish the assigned questions from the Central Dogma Review packet if they did not do so in class.