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MiSP ENZYME ACTION
Introduction : The subject of this unit, enzymes, is typically a high school topic and is studied in-depth in Advanced Placement Biology. Even so, it can be successfully incorporated into living environment units in an Intermediate Level course.
The topic of enzymes is often part of a biochemistry unit/organic compounds unit. It also can be used when a course studies nutrition and digestion.
At the middle school level, the concepts that should be addressed are that enzymes are vital to life, are organic molecules, synthesized by living things, and that they speed up chemical reactions. High school courses can include the ideas of the active site, enzyme specificity, and the lock and key explanation of enzyme action.
The MiSP will address factors that affect rate of enzyme activity: temperature and concentration of enzyme and substrate. pH is also a factor that affects enzyme activity.
Teacher Resource: http://academic.pgcc.edu/~kroberts/Lecture/Chapter%205/enzymes.html
ILST Core Curriculum – Major Understandings: Standard 4 Living Environment 1.2c, Living Environment Core Curriculum – Major Understandings: Standard 4 1.2h, 2.1g, 2.1i, 5.1f, 5.1g
Objectives:
After completing this unit students will be able to Define enzyme, substrate, and product State that enzymes speed up chemical reactions, are organic catalysts, are proteins, and are synthesized by living things Explain enzyme specificity using the lock and key analogy and explain how active sites create specificity (high school) Collect, graph, and interpret rate of enzyme activity data. Determine and use the unit rate of change (slope) for changes in enzyme activity at different temperatures and concentrations (L2) Determine and apply the formula for a line on rate of enzyme activity graphs (L3)
Day 1 – Introduction to Enzymes
Good resources with visuals: http://www.ngfl- cymru.org.uk/vtc/20050330/Biology/keystage4/enzymes/enzymesac/introduct/defau lt.htm
http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work. html
Day 1 introductory discussions will depend on prior teaching and learning and the type of course. Topics/activities may include Demonstrations of general catalysis and/or enzyme activity. One can use the digestion of starch by amylase to produce sugar or the catalase-hydrogen peroxide reaction. Catalase can be purchased from chemical supply vendors and is found in a variety of living tissues including yeast, liver, potatoes, blood, and ear wax. {Include a demonstration to show that enzymes can be reused.} Catalytic action (speeding up chemical reactions/allowing reactions to occur at a greater rate at a lower temperature)/substrates, products Enzymes are proteins and are synthesized in human beings Enzymes are specific (active site, lock and key mechanism) The catalase facilitated breakdown of hydrogen peroxide into water and oxygen Enzyme activity can be affected by substrate concentration, enzyme concentration, temperature, coenzymes, and pH. It is recommended that students do these labs as inquiry experiences. Students will observe how temperature and concentration affect enzyme activity. Teachers may want to explain pH’s affect on enzymes as part of the introductory activity. Discussing pH is optional. Remember that different enzymes are affected by pH in different ways:
QUESTION OF THE DAY:
There is an enzyme in fresh pineapple called bromelain that breaks down the chemical (collagen protein) in Jell-O that makes it “jell.” So, if you put fresh pineapple in your Jell-O, it will not jell – it will remain a liquid. If you use canned pineapple, the problem does not occur. The Jell-O will harden. Why does canned pineapple not do the same thing to Jell-O that fresh pineapple does?
Day 3 and 4 – The Effect of Substrate Concentration on the rate of enzyme activity
Lab notes: Students should wear goggles. Computer temperatures probes may be used – vendors have developed protocols Review the MSDS for hydrogen peroxide
Same catalase preparation as Day 2. A new preparation should be made. The enzyme will lose its activity overnight even if kept under refrigeration.
This lab is similar to the enzyme temperature activity. Much of the introduction and basic procedures are the same. With two days to work, the students should be able to complete this lab activity.
Typical enzyme rate graphs are shown below. Note that our graphs will not look like this because we are not graphing rate, the students will be graphing the time for the reaction. (Slower reactions – longer time, Faster reactions - shorter time) So the graphs will be the inverse and we will not have zero reaction rates (when the enzyme is denatured or when there is 0% substrate)
Day 5 Administer assessment: Enzyme Worksheet #.
