biology

Introduction to Biology and Lab-BIO105

Lab 5: Characteristics of Enzymes

Introduction

Almost all reactions in the body are controlled by enzymes. Many different enzymes are required to break down food (carbohydrates, fats, and proteins) into forms usable by the cells. Other enzymes are necessary for the cells to synthesize their own carbohydrates, fats, and proteins. Enzymes are special types of protein whose function is to control cellular reactions. These reactions occur very quickly.

Speed is necessary to maintain constant cellular conditions. Enzymes are used over and over again by the cells to catalyze life-sustaining reaction.

Enzymes are very sensitive to their local surroundings. Changes in pH, temperature, ion concentration, and types of ions or molecules in solution drastically alter the enzyme’s ability to catalyze a reaction. Enzymes are also very specific in catalyzing only one reaction out of the millions that are possible.

An enzyme is a protein and is built of amino acids. Each enzyme has a specific three-dimensional structure. This structure contains a pocket called, the active site where the reaction occurs. The enzyme and substrate (reactant) combine to form the enzyme substrate complex. The substrate, activated by the enzyme in the complex, reacts to form the products, regenerating the enzyme.

Various forces (hydrogen-bonding, salt bridges, disulfide linkages, etc.) hold the enzyme in its specific shape. These forces can be overcome by denaturants, which inactivate the enzyme. One such denaturant is heat. A heated enzyme (boiled) loses its three-dimensional shape and becomes inactive or denatured.

Another method of inactivating an enzyme is to introduce a chemical inhibitor capable of specifically binding to the active site of the enzyme. These inhibitors prevent normal substrate-enzyme interactions.

Objectives: In this virtual experiment we will investigate properties of enzymes. The objective of this lab is to determine the effects of temperature, pH, and substrate concentration on enzyme activity. Students will work through a virtual activity to learn about: Enzymes, substrates, products, active sites, enzyme specificity, enzyme shape, factors affecting enzymes (temperature, pH, substrate concentration), data analysis, reading of graphs, condensation/dehydration synthesis, hydrolysis, monomers, polymers etc.

A. Procedure

1. Go to the virtual lab at:

https://biomanbio.com/HTML5GamesandLabs/LifeChemgames/enzymatichtml5page.html

Click on “start a new game”

2. Read through the background on enzymes. Then, click on the bottom blue button “Tap or Click Here!”

3. Click on “what are enzymes?”

4. Click on “specificity” and then play the game to understand what it means for an enzyme to be specific.

5. Then click on “experiments” in order to understand the relationship between enzyme activity and temperature and other factors affecting enzyme function (pH).

6. Question 1: What is an enzyme?

7. Question 2: What does it mean for an enzyme to have an optimal temperature?

8. Question 3: What does the reaction rate slow down drastically when the temperature gets too high?

9. Question 4: How did the enzyme behave when the temperatures were extremely hot? How did the enzyme behave differently than in lower temperatures? Explain.

10. Question 5: What does it mean for the enzyme to be denatured?

11. Finally take the quiz and a screenshot of the quiz to record that you took the quiz.

12. Submit under Moodle for a grade:

1. a one-page summary of what you learned in this virtual lab along with

2. Your responses to the 5 lab questions (see above)

3. Screenshot of the quiz which you took for full credit.

Make sure to reference the website in APA style.

13. Look up how to do APA citations at Purdue OWL website:

https://owl.purdue.edu/owl/research_and_citation/apa_style/apa_formatting_and_style_guide/general_format.html