ENZYME LAB PRESENTATION By May, Nam T., Por, Parn, Mook, Mix
(10-9)
Slide 2
Objective To study how pH, temperature, ionic conditions,
substrate concentration affects enzyme activity
Slide 3
Something you should know before : -The enzyme that is used in
this experiment is urease , which contains in the soya bean. -Soya
suspension, in this experiment, is used as an enzyme for urea. -The
substrate is the urea. -Enzyme urease breaks down urea to ammonia
and carbon dioxide. CO(NH2)2 + H2O 2 NH3 + CO2 Urea + water ammonia
+ carbon dioxide
Slide 4
Something you should know before (cont.) : -Ammonia that is
produced has a high pH (basic). -We can detect ammonia by using the
red cabbage indicator and also by smelling.
Slide 5
Hypothesis -Drop citric acid change to red -Drop sodium
bicarbonate change to blue -Drop distilled water no change
Procedure 1: Investigation of urease enzyme and Indicator
Slide 6
Result Test tube 1- Citric Acid Test tube 2- Sodium Carbonate
Test tube 3- Distilled Water Color (initial)Purple Color
(final)RedDark greenish blue Purple
Slide 7
Slide 8
Answer questions 1. Why is it important to have three reference
tubes? Each reference tube contains acid, base and distilled water,
which is neutral, respectively. They are a control for reaction
between red cabbage indicator and acid, red cabbage indicator and
base, and the same indicator and water. They show the different
results after the indicator reacts with acid and base.
Slide 9
2. Can you predict what color of the solution will be if the
urease enzyme converts urea to ammonia? I can predict that the
color of the solution will be blue or green, as the result, when
red cabbage indicator reacted with sodium carbonate, which is
basic, it became blue or green.
Slide 10
Procedure 2: Investigating the effect of urease from soya beans
on urea. Hypothesis -The test tube which contains both urease and
urea will be the only one test tube that changes the color.
Slide 11
Result Test tube 1- Urea Test tube 2- Urea + Soya Test tube 3-
Distilled water + soya Color changePurpleGreenLight purple
Odor(smell)No smellLight smellStrong smell
Slide 12
Slide 13
Answer the questions 1. What are the purposes of procedure 2?
(Think about the total contents in each tube, and what can the
results from each tube tell us.) The purpose of procedure 2 is to
test the enzymatic working, which shows that if there is only the
enzyme (only urease) or only the substrate (only urea), the
enzymatic reaction cannot occur. The reaction will occur when there
are both the enzyme and the substrate fitting each other such that
the test tube 2 represents.
Slide 14
2. Why do we need to add an enzyme into a test tube without
urea even though we can predict that no enzyme activity can occur?
Because we want to make sure that we can use this indicator to test
the pH changing. If we add the enzyme into the test tube without
urea (test tube 3) but the color changes then we cannot use this
indicator to test in this experiment. Although we can predict that
no enzyme activity can occur but we have to double-check the
result.
Slide 15
Hypothesis -The color of the solution of both test tube with 5%
NaCl and with 10% NaCl will change to green. Procedure 5: Effect of
the concentration on urease
Slide 16
Result Test tube 1- 5% NaCl Test tube 2- 10% NaCl Test tube 3-
Saturated NaCl Color changeClear greenClear greenish blue Opaque
blue Odor(smell)Light pungent A bit strong pungent
Slide 17
Slide 18
Answer the questions 1.How does ionic condition affect the
urease activity? How do you know? The ionic condition affects the
rate of the urease activity. The rate of the activity depends on
the ionic concentration; if the concentration of the ionic
substances increases, the rate will increase. However, too much
concentration can stop the reaction as well that means the enzyme
will not cause the reaction anymore. We can know that from the
color of the solutions from the results. When the activity occured,
the color of the solution turned green. If the solution is blue,
the activity did not occur.
Slide 19
2. From your results, what ionic condition would you use and
avoid if you have to conduct an experiment using urease enzyme and
why? We would use the 5% NaCl ionic condition and avoid the
saturated NaCl ionic condition, because, according to the
experiment, the 5% NaCl ionic condition could use the most
efficiently, it could cause the faster activity; whereas the more
than 5% NaCl can lower the rate of the activity. Moreover, the
saturated can stop the activity because of the too much
concentration of the ionic substances, NaCl.
Slide 20
3. Your special task is to try and deactivate the enzyme with
table salt. We can deactivate the enzyme by adding a lot of salt.
Much concentration of the salt can deactivate it.
Slide 21
What were you able to learn from this experiment? -Temperature,
pH, ionic condition, substrate concentration are all the factors
that affect enzymatic reaction. -Enzyme can work in only its
properly condition. -Two ways to detect the reaction; indicator and
smell -Red cabbage indicator can be used to detect ammonia.
Slide 22
What were you able to learn from this experiment? (cont.)
-Urease is an enzyme of urea that can be found in soya beans, as in
the experiment, the enzyme activity causes when we added soya.
-When urease breakdowns urea, ammonia and carbon dioxide are the
products. -How to work in group
Slide 23
Did your results support the prediction made before conducting
the experiment. If it did not, then explain why. => All the
results have supported our prediction or hypotheses.
Slide 24
Any experimental errors? How can you avoid these errors in the
future? The contaminated urea Do not suck the chemical directly
from the bottle Do not pour the rest chemical back into the bottle
Keep the chemical correctly, close the lid tightly Check the
chemical before starting the experiment