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Regulating Genes

Find out what Darwin never knew. He understood that species adapt and change, but he didn't understand the actual processes that made this happen. New discoveries in the emerging science of "evo devo" are helping to solve these mysteries. In this feature, you’ll see for yourself how genetic mutations influence the development of an individual creature. Study how the mutations in different regions of the DNA impact the expression of genes. Predict how the mutations impact the development of the creature’s traits. And finally, observe the developed creature and explain how the mutation gave rise to any changes.

Launch Interactive

Observe and manipulate an interactive model that illustrates the mechanisms that govern gene regulation during an organism's development.

Background Essay

Darwin tried to understand how the extraordinary diversity of life on Earth came about. His theory of evolution explains that species adapt and change, resulting in a wide variety of animals. But he admitted that he didn't understand how this change happened. If evolution is the survival of the fittest, how are the fittest made?

Until recently, scientists presumed that the genes involved in making different animals—say a human and a fruit fly—were very different. The genes required to make wings, for instance, must be quite different from the genes required to make limbs. To understand how evolution works, therefore, all you would need to do is identify the genes of every creature and compare their differences.

Between 1990 and 2003, scientists did just that—they mapped the genomes of humans as well as a few other animal and plants species. Scientists expected that complex species like humans would have many more coding genes than simpler species.

They were wrong.

In fact, humans had a fraction of the expected number of genes, and about the same number as some microscopic worms. What's more, the genes humans do have are remarkably similar to those found in other animals. Theories about the quantity and diversity of genes, therefore, had fallen short in explaining both the diversity of life on Earth as well as the complexity of humans. What, then, explains how similar sets of genes can result in such an incredible diversity of life?

The new science of "evo devo" (evolutionary developmental biology) is applying lessons from the development of individual organisms to a broader understanding of changes in groups over the course of evolution. By studying developing organisms, scientists have learned about areas of DNA that "regulate" genes by controlling where, when, and to what degree they are turned on and off. Thus, the same gene can produce very different traits in two species, depending on how it is regulated during development.

Moreover, if species diversity comes in part from differences in how genes are regulated, then it follows that mutations in regulatory mechanisms—not just in genetic code—can explain how species develop new traits.

Download PDF Version of this essay

For Teachers

This is a two-day student-directed activity. Download and print the Teacher's Guide: Regulating Genes (PDF) for essential background information and suggestions for ways to support the activity.

Day 1. Devo: Understanding Biological Development

The first part of this activity uses an online tool that models the processes of gene regulation by allowing students to trigger a DNA mutation and then see how it impacts gene expression during an organism's development. By observing how genes are turned on or off, students can make predictions about traits then see the results in a developed creature.

Day 2. Connecting the Devo to the Evo

By studying how mutations to DNA can influence the development of individual organisms, students learn about the primary driver of evolutionary change. But to understand how this plays out in evolution, they need to understand how traits that arise through mutation are preserved within groups.

The second day of this activity focuses on how the creatures developed in the gene tool might interact with their environments. Students group their creatures by traits, then explore the viability of the creatures in a few environmental scenarios. Students discuss which type of organism might be at an advantage or disadvantage as a result of its mutation, in each scenario.

Key Vocabulary

  1. coding gene: The region of DNA containing code that can be translated into proteins.
  2. promoter: The non-coding region of a gene that is responsible for regulating the gene’s expression. Promoters are located next to the gene they regulate.
  3. enhancer: The mechanism within a gene’s promoter region that, in conjunction with transcription factors (see below) is responsible for activating or repressing the gene's expression at a specific time and place during development.
  4. transcription factors: Proteins that bind to a gene’s enhancer to determine when, where, and to what degree that gene is expressed at different stages of development. They are themselves the product of other genes known as “regulator” genes.

Download the full Teacher's Guide

Student Resources

Use this worksheet to guide your investigation and to record your observations.

Download the Student Worksheet

Credits

DESIGN & PRODUCTION

Inquirium LLC

PROGRAMMING

Creative Bottle

Science Advisor

Carole Labonne, Ph.D., Northwestern University

Special Thanks to:

Mark Biggin, Ph.D., University of California, Berkeley
Chris Lowe, Ph.D., University of Chicago
Robert Holmgren, Ph.D., Northwestern University

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