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How does DNA control traits in living things?

Learning Targets

Learning Experiences

Learning Targets

Learning Experiences

70 I can use data to support the concept that changes in DNA impact protein function in predictable ways. (3, 3c) 71 I can categorize types of mutations and use a model to show how changes in DNA can result in changes in protein function. (3, 3c) 72 Based on my understanding of the Central Dogma of biology, I can predict how specific changes in DNA (both large scale and small) will impact protein function. (3, 3c) 73 I can interpret the impacts of DNA changes using lab techniques such as gel electrophoresis, PCR, or computer-based resources such as NCBI. (3, 3a, 3c)

Students return to the principles of the Central Dogma but through the lens of genetic variation and its potential effects. Through a series of activities, they classify types of DNA changes (deletions, insertions, and substitutions) and identify the impact of those changes on the structure and/or function of the resulting amino acid sequences. Similarly, when presented with a specific alteration in a protein’s structure or function, students can evaluate the Central Dogma “in reverse,” generating an evidence-based hypothesis that predicts the causative change in the DNA sequence. Students extend their learning and link DNA changes to observable traits in the natural world. With respect to human health, a causal relationship is demonstrated between certain genetic variants and disease, providing students the opportunity to analyze a variety of diagnostic techniques that identify genetic variation in a clinical setting. Where useful, students incorporate data from publicly available research tools such as NCBI. NOTE: the focus of this exercise is linking genetic change to altered protein function and the appearance of a different trait or disease. Details regard- ing inheritance patterns are outside the boundary of these conversations. Utilize paper simulations, web-based simulations, animations, video, or lab- oratory activities involving DNA sequencing, PCR, and gel electrophoresis to familiarize students with each process. Gel electrophoresis simulations can range from determining paternity to criminal identification. PCR simulations should show how genes are amplified for research. DNA sequencing simulations show how genes are located and analyzed. Explain how common laboratory techniques (described above) are used to obtain evidence that supports the premise that DNA changes may affect proteins and in turn the appearance of traits.

68 I can use a model to explain protein folding in terms of the rules of chemistry and physics to describe how the folding of the protein affects its func- tion. (1, 3) 69 I can relate the levels of protein structure to the final three-dimensional shape and functionality of the protein. (1, 3)

To become a functional protein, a translated chain of amino acids must be folded into a specific three-dimensional shape. Students create and manipulate polypeptide models to demonstrate that a protein is a “linear sequence of amino acids that spontaneously folds following rules of chemistry and physics.” Illustrations and models are categorized by students to identify primary, secondary, tertiary, and quaternary levels of protein structure. Students examine in detail a specific protein (such as hemoglobin, collagen, or insulin) to show how the levels of protein structure relate to the protein’s overall function. Returning to prior learning about enzymes (learning targets #47-49), students relate protein structure to enzyme function and discuss the causes and impacts of protein denaturation on both enzymes and structural proteins.

Teacher Resources

Simple protein models can be constructed using colorful plastic beads and floral wire or pipe cleaners. These protein models can be stored and used multiple times throughout the course. Amino Acid Starter Kit — 3D Molecular Designs Students will practice protein folding by placing amino acids models in various locations on a flexible foam toy. Toobers and Tacks — 3D Molecular Designs Students explore how the chemical properties of the 20 amino acids determine the final shape of a protein. Designer Enzymes — Alabama Science in Motion M2DesEnz Students explore the roles of proteins in living organisms, by designing an enzyme to perform a specific function. bit.ly/AMSTI-ASIM

Teacher Tip A variety of paper electrophoresis activities are freely available from the Internet.

Teacher Resources (see page 42)

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A Field Guide to the Alabama Standards

The Biology Compendium

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