High school

Gene regulation, enzyme specificity, heredity

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Last Updated Dec 1, 2020

This unit will introduce students to lactose intolerance.  Students will develop questions about a case of a girl with symptoms of stomach pains, gas, and diarrhea.  Throughout the unit, students will analyze pieces of evidence to answer their questions and eventually come to understand the mechanism of lactose intolerance.

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Learning Objectives

Students will know

  • Carbohydrates (monosaccharides and polysaccharides)
  • Mutations in a gene can change gene function
  • Mutations in regulatory regions can change gene expression
  • Enzyme substrate relationship

Students will understand

  • Monosaccharides are building blocks of polysaccharides
  • Enzymes can break down polymers into monomers
  • Enzymes are specific to a substrate
  • Gene expression is regulated

Students will be able to

  • Analyze data to determine if Maria had an allergic reaction
  • Analyze data to determine milk types based on glucose data and response to specific enzymes
  • Analyze RT-PCR data to determine the expression of LCT in Maria
  • Collect data about lactase’s activity in different environments to determine where in the body lactase is usually expressed.
Standards Alignments + Connections

Next Generation Science Standards Connections

HS-LS3-1: Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions of characteristic traits passed from parents to offspring.

Texas Essential Knowledge and Skills Connections

B.6D: recognize that gene expression is a regulated process

B.6E: identify and illustrate changes in DNA and evaluate the significance of these changes

UNIT PLAN

Introductory Phenomenon

Students should be introduced to the story of Maria, a girl who recently started having symptoms of diarrhea, gas, and stomach pains.  They will also be given the food she consumed that day in addition to her family’s medical history.  After reading Maria’s story, students are encouraged to ask questions about what is causing Maria’s symptoms.

Questions may include:

Did she eat anything else that could have caused this?

Could she be allergic to something in the milk or the other foods?

Was the milk expired?

What kind of milk was it?

When does her mother get these symptoms?

Did she get a disease from her mom’s side of the family?

Activities to Gather Evidence

Could it be allergies?

Allergic Response Data

Students will be given blood count data for Maria and two control groups.  Students will be asked to determine the differences between the normal and allergic samples and draw conclusions about Maria’s situation

What type of milk was in the fridge?

Milk Comparison

Students will analyze the differences between soy and cow milk and will use a computer model to compare the molecular structures of sucrose and lactose.

How are these sugars digested?

Sugar Breakdown

Students analyze data about glucose concentration of milk samples and enzyme use in order to determine which sample contained which milk type.  Students learn about enzymes and their functions.

Is lactose intolerance caused by a mutation in the LCT gene?

Lactose Intolerance Genetics

Students learn about the lactase gene (LCT) and analyze RT-PCR data to see if Maria is expressing lactase.

How is gene expression regulated?

Regulation of Gene Expression

Students learn that Maria has a mutation in a gene upstream of LCT.  Students learn about gene expression in eukaryotes and how a mutation in a regulatory element can change a gene’s expression.

Where in the body is Maria's expression of LCT turned off?

How Gene Regulation Allows for Specialized Cells

Students use a simulation to see what conditions (pH and temperature) allow for the highest enzymatic rate.  Students will compare this information to data about temperature and pH throughout the human body to determine where lactase expression is usually turned on.

Conclusion Assessment

Students construct a claim backed up by evidence and reasoning to answer the following question:

Additional Resources