Name: Ellen Do

Date: April. 23th, 2019

Title: The effect of temperature on enzyme 

Purpose: to determine how the temperature affects the reaction rate of enzyme, specifically lactase. 

Questions: How can enzymes affect in different enzyme?

Hypothesis: If the temperature is too high or too low, the enzyme will be denatured. Therefore, the enzyme will work the most effectively at the range around body temperature. Furthermore, when the temperature is below 37 degree Celsius, an increase in temperature will lead to an increase in the reaction rate. 

Materials: 

• 5 test tubes 

• 5 beakers 
• Test tube rack 
• Milk 
• Graduated cylinder 
• Lactase (drop) 

• 5 Glucose test paper 
• Ice bath 
• Hot plate 
• Thermometer 

 

Procedure/Methods: 

 

• Measure 10ml of milk using the graduated cylinder and pour it into each test tubes. 
• Heat/Ice bath the milk until it reaches the following temperature. The temperature for each tube is 5, 10, 37, 45, 60 Celsius. 
• Add water with the corresponding temperature in the beakers and place them under the test tubes so that the part of the test tubes containing milk is submerged in the water. 
• Add 1 drop of lactase solution into each test tube. 
• Frequently check the temperature of the solution to make sure that the temperature of the milk is maintained. 
• After 5 minutes, dip the glucose test papers into the solution – one test paper per test tube. 
• Compare the colour on the glucose test paper with the colour chart on the glucose test paper container. 

Data + Observations:  The concentration of glucose in different temperature 

 

Temperature (Celcius)	Concentration of glucose (mmol/L)
5	0
10	10
37	111
45	55
60	6

Graph: The effect of temperature on enzyme

 

• As the temperature increases, the reaction speeds up. However, the reaction slows down when the temperature keeps rising above the range from 35-38 degree. The enzyme is most effective in the range from 35 to 38 degree. 

 

Analysis & Conclusion: 

• Analysis: when the temperature rises, there is more kinetic energy in the molecules. Thus, the molecules move faster and bond to the enzyme more frequently, resulting in an increase in reaction rate. However, the temperature above 45 degrees would cause the enzyme to denature, because the apoenzyme is a protein. Therefore, the enzyme cannot effectively participate in the reaction, resulting in a decrease in the reaction rate. There is glucose at 60 degrees because high temperature also causes the protein in the milk to denature, forming glucose and galactose. 
• Conclusion: the enzyme is most effective around 37 degree Celsius, which means the reaction rate is the fastest. As the temperature moves away from that range, the enzyme is less and less effective, leading to a slower reaction rate.