Synopsis of Experiment
The effect of pH, temperature, or substrate concentration on sucrase activity will be assessed in experimental [active sucrase present] and control [active sucrase absent] sucrose solutions by measuring the product [glucose or fructose] produced. The following process is used.
Sucrose solutions - with and without active sucrase - are hydrolyzed during a 20-minute incubation. Following incubation, DNS (dinitrosalicylic acid) is added. The pH of the DNS solution denatures sucrase and stops the reaction, thus fixing the concentration of the reaction products.
After heating the solutions to 90°C (194°F), DNS will convert to ANS (3-amino-5 nitrosalicylic acid) if a monosaccharide - like glucose or fructose - is present. The amount of ANS, a reddish-brown colored chemical, is determined using a spectrophotometer, an instrument that measures the amount of light that is transmitted through a colored solution. The more ANS in the solution, the greater the optical density will be. The amount of ANS produced is analogous to the amount of product produced from the enzyme reaction.
- The effect of pH on sucrase activity in sucrose solutions with varying pH values from 3.0 to 9.0 will be assessed.
- The effect of temperature on sucrase activity in sucrose solutions at varying temperatures from 10°C (50°F) to 70°C (158°F) will be assessed.
- The effect of substrate concentration on sucrase activity in solutions with different concentrations of sucrose will be assessed.
Predictions
Based on what you know, predict the outcome of the experiment. Complete the numbered statements below by choosing one response for each number.
When you are done, click the Submit button to save your responses to the laboratory report.
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Scroll down to select Variables.
IMPORTANT: If you do not click the Submit to Lab Report button, the answers will not appear in your Laboratory Report. You will see “undefined” in the answer blanks for Predictions and Materials and Methods when you Save to PDF.
You have correctly defined all of the variables.
Click or tap the Submit to Lab Report button to continue.
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Variables
Now determine the dependent, independent, and controlled variables for each experiment in this laboratory activity by clicking on the appropriate answers.
Check your answers until you have chosen all variables correctly. There will be one choice for Dependent and Independent Variables and multiple choices for Controlled Variables. When you are done, click the Submit button to save your responses to the laboratory report.
IMPORTANT: If you do not click the Submit to Lab Report button, the answers will not appear in your Laboratory Report. You will see “undefined” in the answer blanks for Predictions and Materials and Methods when you Save to PDF.
