Students collect and analyze data about enzyme activity. In this activity students perform a simple spot plate test to determine whether a certain enzyme is specific for only one disaccharide. In fact, the task is designed to provide verification that, indeed, enzymes are specific for only one substrate.

The task assesses students' ability to make simple observations, collect and analyze data, and interpret their results to draw appropriate conclusions.

This task is designed to take students approximately 30-35 minutes to complete.

Overall Task Content Area:

Life Science

Specific Knowledge Areas:

Cellular reactions

Performance Expectations:

• conducting investigations
• using equipment
• gathering, organizing, and representing data
• formulating conclusions from investigational data
• applying scientific principles to develop explanations and solve new problems

National Science Education Standards:

12 A SI 1: Ability necessary to do scientific inquiry: Grades 9-12
1.4 Formulate and revise scientific explanations and models using logic and evidence. Student inquiries should culminate in formulating an explanation or model. Models should be physical, conceptual, and mathematical. In the process of answering the questions, the students should engage in discussions and arguments that result in the revision of their explanations. These discussions should be based on scientific knowledge, the use of logic, and evidence from their investigation.

1.3 Use technology and mathematics to improve investigations and communications. A variety of technologies, such as hand tools, measuring instruments, and calculators, should be an integral component of scientific investigations. The use of computers for the collection, analysis, and display of data is also a part of this standard. Mathematics plays an essential role in all aspects of an inquiry. For example, measurement is used for posing questions, formulas are used for developing explanations, and charts and graphs are used for communicating results.

12 C LS 1: The cell: Grades 9-12
1.2 Most cell functions involve chemical reactions. Food molecules taken into cells react to provide the chemical constituents needed to synthesize other molecules. Both breakdown and synthesis are made possible by a large set of protein catalysts, called enzymes.

(Use the "hot" link on the PALS home page to check the full text of related National Science Education Standards, if desired.)

National of Council of Teachers of Mathematics:

DAP1: Formulate questions that can be addressed with data and collect, organize, and display relevant data to answer them.

PS2: Solve problems that arise in mathematics and in other contexts.


General Instructions to the Teacher:

This task is designed to be done by individual students working alone take students approximately 30-35 minutes to complete.

Before using this task, students should have studied specific enzymes and their substrates, chemical reactions and the use of word equations to describe chemical reactions, as well as the specific processes of dehydration syntheses and hydrolysis (i.e. digestion) reactions.

Students should be ready to work as soon as the period begins. The materials should be set out at each lab station, if possible. A central supply area, if needed, should be easily accessible. All supplies should be clearly labeled.

Materials for Are Enzymes Specific for their Substrates:

At this station students should have:

• 1% glucose solution
• 3 unknown disaccharide solutions: A, B, and C;
  "A" = water; "B" = 1-3% Lactose solution; "C" = water
• Enzyme solution: LACTAID Liquid (over-the-counter in grocery or drug store)
• Test strip indicator for glucose (over-the-counter in drug stores)
• Spot plate (depression plate) with at least 9 to 12 wells
• China marker to mark spot plates

Advance Preparation:

Prepare solutions and dispense in either dropper bottles or microscale disposable pipettes.
Label all containers.

• Glucose solution: 1 gram of glucose dissolved in 99 ml distilled water.
• Lactose solution: 3 grams of lactose dissolved in 97 ml distilled water.
• Lactase solution: LACTAID Liquid (over-the-counter in grocery or drug stores).
• 1 small bottle per 100 ml distilled water.

Safety:

Remind all concerned NOT TO INGEST ANY MATERIALS. Be certain MSDS information is available for each chemical substance used in this activity.

• Be careful.
• Teachers and students should always exercise appropriate safety precautions and utilize appropriate laboratory safety procedures and equipment when working on science performance tasks.