Shared Biochemistry

Same Gene, Different Organism

This video introduction to the module uses two bioengineering examples to set up the question, Why can living things decode the information in each other’s genes?

Project video to the whole class. Spend a few minutes generating ideas about the question: Why can living things decode the information in each other’s genes? You may wish to record the ideas to revisit later.

• Organisms can decode the information in each other’s genes to build identical proteins.

5-10 minutes

What Are Proteins?

This video introduces the structure and diversity of proteins.

Project video to the whole class.

• Proteins are made from amino acids.
• Different combinations of amino acids make different proteins.

5-10 minutes

Types of Proteins

Students often have a hard time understanding the diverse roles of proteins in the body. This activity introduces the functional roles of 9 categories of proteins through specific examples. It works well as a quick demo, projected to the class.

See teacher guide for more information and a summary chart.

• Proteins build and operate an organism, working at the cellular, tissue, and organismal level.

10 minutes

What Are DNA and Genes?

This brief video introduces the structure of DNA.

Project video to the whole class.

• DNA is made of a 4-letter code: A, C, G, T.
• DNA is organized into genes.
• Genes code for proteins.

5-10 minutes

Build a DNA Molecule

This online interactive provides students with more practice with the structure of DNA. Students explore the complementary base-paring rules by building a DNA molecule.

Have students explore individually.

Note: There is no end-point to this activity; one could build the DNA molecule indefinitely.

• DNA is made of a 4-letter code: A, C, G, T.
• A, C, G, T pair together in a specific and predictable way forming a DNA molecule.

10 minutes

Computers with internet access

Will NOT work on tablets

How a Firefly's Tail Makes Light

This video provides a brief overview of protein synthesis, using firefly luciferase as an example. It builds on earlier activities that explore DNA and proteins, and it precedes a more detailed look at protein synthesis.

Project video to the whole class.

If students are unfamiliar with fireflies, first show the short Introduction to (actual) Fireflies video.

• Cells make specific proteins by reading the genetic code in specific genes.

Students see a real-life example highlighting the relationship between a gene, the protein it codes for, and its function in an organism.

5 minutes

Transcribe and Translate a Gene

This interactive provides a more-detailed look at transcription and translation. Students click and drag their way through transcribing a gene to make mRNA and translating the mRNA to build an amino acid sequence. The next activity in the sequence will offer more practice with a paper model.

Have students explore individually.

• The arrangement of DNA building blocks in a gene specifies the order of amino acids in the protein it codes for.
• Amino acids are the building blocks of proteins.
• The sequence of amino acids in a protein determines its structure and function.
• Living things make proteins the same way.

This is an animated model of the molecular system responsible for protein synthesis.

15 minutes

Computers with internet access, headphones

Paper Transcription and Translation

This hands-on activity reinforces the processes of transcription and translation. Using paper cut-outs, students follow the rules of complementary base pairing to build an mRNA molecule, then translate the mRNA codons to assemble amino acids, building a protein. At the end, they learn which of 5 actual proteins they’ve built. (DNA and amino acid sequences have been abbreviated.)

Have students work individually or in pairs.

You may wish to review with the class how the structure and function of proteins is dictated by the DNA sequence of genes (structure and function of DNA).

• The arrangement of DNA building blocks in a gene specifies the order of amino acids in the protein it codes for.
• Amino acids are the building blocks of proteins.
• The sequence of amino acids in a protein determines its structure and function.
• Living things make proteins the same way.

Students use a paper model to make sense of the steps and molecules involved in transcription and translation.

60-90 minutes

Copies, scissors, tape, paper clips

Transcription and Translation Assessment

This quick formative assessment checks to see how well students understand why organisms can decode the information in each other's genes.

10 minutes

Task students with making a poster or PowerPoint presentation that answers the prompt, "Why can living things decode the information in each other's genes?" You may want them to use an example such as GFP or spider silk. It may be useful to have them use the cut-outs and instructions from Paper Transcription and Translation.

Shared Functions, Shared Genes

A core set of about 300 genes underlie the basic biochemical components and functions for all living things. We can reason they were present in an ancestral life form.

This video highlights the biochemical similarities of living things very broadly. Its purpose is as follows:

• Show that very diverse life forms are similar at a molecular level.
• Introduce the idea that these similarities are encoded by the same genes.

Project video to the whole class; review the main points (listed above) as a group.

• All living things are made of the same molecules. These molecules carry out the same functions for all living things.
• All organisms have some genes in common.

10 minutes

Shared Functions, Shared Genes (video)

Comparing Amino Acid Sequences

In this hands-on activity, students work in small groups to compare amino acid sequences for a particular protein from a mouse to the same protein from 5 other organisms, then calculate the percent of amino acids that are identical. All groups combine their data, revealing a pattern in the percent identity to mouse for 10 organisms across 5 different proteins.

See Teacher Guide for further instructions.

To wrap up, you may wish to review Shared Functions, Shared Genes.

• Organisms make similar proteins.
• A core set of genes is required for basic life functions; these are common to all types/domains of organisms.
• There is a greater percent identity in proteins among organisms that are more similar to each other.

Students compare the amino acid sequences of real proteins across 5 different organisms.

The proteins from other animals tend to be more similar to mouse proteins; those from plants or bacteria tend to be less similar.

45-60 minutes

Large space on a wall or white board
Copies, tape, scissors, calculators

The Trouble with Cognitive Bias

This video is the first activity in a series of lessons spread throughout the unit that are designed to prepare students to write a supported argument. This video introduces the following ideas:

• Scientific argumentation is a means to defeat common cognitive biases.
• A good argument has three components: claim, evidence, and reasoning.

Project video to the whole class.

• (Argumentation) Scientific argumentation combats natural human biases.
• (Argumentation) Scientific arguments have 3 components: claim, evidence, and reasoning.

This video introduces students to the components of an argument: claim, evidence, and reasoning.

10 minutes

Evaluating Arguments

This activity helps familiarize students with the parts of an argument as they compare good and bad arguments about a topic.

Have students work throug the arguments individually or in pairs. You may wish to complete the insulin arguments first as a demo to the class.

• (Argumentation) Scientific arguments have 3 components: claim, evidence and reasoning.
• (Argumentation practice) Identify the components of an argument (claim, evidence, and reasoning).
• (Argumentation practice) Evaluate a poorly constructed and a better argument and explain why one is better.

Students identify the components and evaluate arguments.

30-60 minutes

Before moving on, make sure your students understand the following:

• Living things share biochemical features that are encoded by DNA.
• Proteins underlie the structure and function of living things.
• Living things make proteins the same way.
• Living things make similar proteins.
• The arrangement of DNA building blocks in a gene specifies the order of amino acids in the protein it codes for.