27 Jun Biology 251 (Human Physiology) – Enzymes: Temperature, pH and Specificity Lab..
Question
ONE SENTENCE FOLLOWING ABSTRACT THAT SUMMARIZES DATA RESULTS FOUND IN LAB THAT
SUPPORTS THIS PARAGRAPH BELOW
By learning how enzymes act as catalysts to lower the activation energy required for a
reaction to occur in both catabolic and anabolic processes we studied competitive
inhibition, negative feedback, and enzyme specificity using lactase on various
substrates as well as the effects of temperature and pH on the ability of lactase to break
down lactose.
HYPOTHESIS
IF/THEN ASSUMPTION IN A STATEMENT THAT CAN BE
SUPPORTED BY DATA IN LAB
PROCEDURES
In exercise one; we prepared a five percent sucrose solution by using the digital scale
to weigh 2.5 g of sucrose. We placed the sucrose into one of the plastic cups provided
in the LabPaq. We labeled the cup 5% Sucrose with the marking pencil. We
measured 50 mL of distilled water with the graduated cylinder and added the water to
the 2.5 g of sucrose in the 5% Sucrose cup; we mixed it with a stirring rod until the
sucrose dissolves. We cleaned the stirring rod thoroughly and dried it. We then
prepared a lactose solution by retrieving one lactase pill and another plastic cup. We
crushed the lactase pill between two spoons over the plastic cup. We placed the
crushed pill into the plastic cup. We labeled the cup Lactase Solution. We measured
200 mL of distilled water with the graduated cylinder and poured it into the plastic cup
containing the crushed lactase pill; we mixed with a stirring rod until dissolved. We
cleaned the stirring rod thoroughly and dry it. We measured 50 mL of milk with the
graduated cylinder and poured it into a clean plastic cup. We cleaned the graduated
cylinder thoroughly and dried it. We obtained the well plate. We labeled five of the
wells A through E using the marking pencil, and followed the directions in the steps
below for the contents of the wells. We put three drops of sucrose and three drops of
H2O in test tube A. We put three drops of milk plus three drops H2O in test tube B. We
put three drops of sucrose plus three drops of lactase in test tube C. We put three
drops of milk plus three drops of lactase in test tube D. We put three drops of glucose
plus three drops of distilled water in test tube E. We used a clean, long-stemmed pipet
to add three drops of the sucrose solution to well A. We kept this pipet in the sucrose
solution cup to be used later in the exercise. We used a new, clean, long-stemmed
pipet to add three drops of distilled water to well A. We kept this pipet in the rinsed out
graduated cylinder to be used later in the exercise. By using a clean, long-stemmed
Enzymes: Temperature, pH and Specificity Lab
3
pipet, we added three drops of milk and three drops of distilled water to well B by using
the distilled water pipet. We kept the milk pipet in its cup. We added three drops of the
sucrose solution and three drops of the lactase solution to well C using the sucrose and
lactase pipets. We kept the lactase solution pipet in its cup. We added three drops of
milk and three drops of the lactase solution to well D using the milk and lactase pipets.
By using the pipet containing the 20% glucose solution, we added three drops of the
glucose solution and three drops of distilled water to well E using the distilled water
pipet. While we were waiting for the reaction to occur for five minutes, we obtained five
glucose strips. We labeled them a, b, c, d, and e using the marking pencil. Refer to
Figure 6. We dipped a test strip into the solution in well A for five seconds. We gently
blotted the side of the test strip on a piece of tissue to remove excess solution. If the
strip was not blotted, the glucose concentration will not be accurateit will be too
concentrated. We waited 3060 seconds for the color to develop, and then compared
the test strip to the color. We noted that we must take a reading of the test strip at least
no later than the 60-second mark so it wouldnt be inaccurate. We recorded the glucose
concentration for well A in Data Table 1. We noted that the next reading would produce
a zero. We tested the glucose concentration in the remaining wells labeled B-E. We
repeated these procedures using one new test strip per well. We recorded the glucose
concentrations of each well in Data Table 1. We noted that the next reading would
produce a zero. We saved the sucrose solution, lactase solution, and milk for the next
two exercises. We kept the pipets in their corresponding liquids so that they were not
contaminated with the other solutions. We rinsed the contents of the well plate down
the drain and then thoroughly cleaned and dried the well plate for use in the next
exercise. In exercise two we prepared a boiling water bath. We filled a pot with water
about 5 to 6 cm deep. We placed the pot onto the stovetop. We placed the metal test
tube rack into the pot. We brought the water to a boil. We labeled three 13 x 100 mm
test tubes with the black marking pencil as indicated as; A. 5 mL lactase hot water
temperature, B. 5 mL lactase cold water temperature, and C. 5 mL lactase room
temperature. We stirred the lactase solution (from Exercise 1) with the lactase solution
pipet. We used the pipet to squeeze 5 mL of the lactase solution into the graduated
cylinder. We poured the 5 mL of lactase solution into test tube A. By using the test tube
clamp, we carefully placed test tube A into the test tube rack in the boiling water bath.
We recorded the time that the test tube was placed into the water bath into Data Table
2. We placed test tubes B and C in separate clean plastic cups to hold them upright.
We measured and poured 5 mL of lactase solution into test tube B, and placed the cup
with the test tube in the freezer. We measured and poured 5 mL of lactase solution into
test tube C, and placed the cup with the test tube on the counter at room temperature.
We left the test tubes A and B at the different temperatures for 15 minutes. While we
waited for fifteen minutes we measured the room temperature solution by placing the
thermometer into test tube C for 1 minute. We recorded the temperature in our lab
report. We removed, washed, and dried the thermometer. After the fifteen minute
Enzymes: Temperature, pH and Specificity Lab
4
period we carefully placed the thermometer in test tube A (the boiling water bath) for 1
minute. We recorded the temperature in our lab report. We removed, washed, and
dried the thermometer. We placed the thermometer in test tube B (located in the
freezer) for 1 minute. We recorded the temperature in our lab report. We removed,
washed, and dried the thermometer. We labeled the three wells in the well plate: A, B
and C as illustrated in Figure 8. We prepared the well plate by adding three drops of
milk to three different wells leaving one empty well between the milk wells. We labeled
three, clean long-stem pipets: A, B and C. We retrieved 12 glucose test strips. We
labeled four strips A, four strips B, and four strips C. We used the test tube holder
clamp to carefully remove test tube A from the rack in the boiling water bath. We placed
test tube A in a plastic cup. We removed the test tube B from the freezer. We noted
that if the solution was too solid to draw into a pipet, we would have to wait 3060
seconds for the solution to thaw. By using pipet A, pull a small amount of lactase
solution out of test tube A. We added three drops of the solution to well A. By using
pipet B, we pulled a small amount of lactase solution out of test tube B. We added three
drops of the solution to well B. By using pipet C, we pulled a small amount of lactase
solution out of test tube C. We added three drops of the solution to well C. We waited 5
minutes for reactions within the wells to complete. We dipped a test strip into the
solution in well A for 5 seconds. We blotted the test strip with a piece of tissue to
remove excess solution. We waited 3060 seconds for the color to develop and then
compared the test strip to the color chart shown in Figure 7. We recorded the glucose
concentration into Data Table 2. We noted that we must take a reading of the test strip
at least no later than the 60-second mark so the results wouldnt be inaccurate. We
tested the glucose concentration in the remaining wells B and C, following the same
instructions given in the previous steps. We used one new test strip per well. We
recorded the glucose concentration into Data Table 2. After 10 minutes, we dipped a
new glucose test strip into each of the three wells. We recorded the glucose
concentration into Data Table 2. After 15 minutes, we dipped a new glucose test strip
into each of the three wells. We recorded the glucose concentration into Data Table 2.
After 20 minutes, we dipped a new glucose test strip into each of the three wells. We
recorded the glucose concentration into Data Table 2. We thoroughly cleaned and dried
the well plate so it is ready for the next exercise. In exercise three we placed the well
plate onto our work surface. We labeled four wells A, B, C and D. We left an empty
well between each labeled well. We put 2 drops of buffer pH 3.5 plus 2 drops of lactase
plus 2 drops of milk in test tube A, we put 2 drops of buffer pH 5 plus 2 drops of lactase
plus 2 drops milk in test tube B, we put 2 drops buffer pH 6.8 plus 2 drops of lactase
plus 2 drops of milk in test tube C. We put 2 drops of buffer pH 11.5 plus 2 drops
lactase plus 2 drops of milk in test tube D. We put on our gloves and wore them during
this exercise. We used scissors to cut off the tips of the pipets that contain the pH
solutions. We set the pipets in a clean plastic cup, bulb-end down. We put two drops of
Enzymes: Temperature, pH and Specificity Lab
5
pH 3.5 buffer into well A. We put two drops of pH 5 buffer into well B. We put two drops
of pH 6.8 buffer into well C. We put two drops of pH 11.5 buffer into well D. We added
two drops of the lactase solution to wells A through D. We added two drops of milk to
each of the wells A through D. We waited 10 minutes for reactions to occur. During the
10-minute waiting period, we labeled four glucose test strips A, B, C and D. We then
carefully dipped a test strip into the solution in well A for 5 seconds. We blotted the test
strip with a piece of tissue to remove excess solution. We waited 3060 seconds for the
color to develop, and then compared the test strip to the color chart shown in Figure 7.
We noted that we must take a reading of the test strip at least no later than the 60second mark so they results wouldnt be inaccurate. We recorded the glucose
concentration into Data Table 3. We tested the glucose concentrations in the remaining
wells B-D, following the same instructions given in the previous steps; we used a new
test strip per well. We recorded the glucose concentration in Data Table 3.
OBSERVATIONS
PROVIDE DATA FOR DATA TABLES
Data Table 1: Glucose Concentration
Wells
a
b
c
d
e
Concentration of Glucose
Enzymes: Temperature, pH and Specificity Lab
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Data Table 2: Presence of glucose in wells indicating lactase activity at
various temperatures
Well
Time (min)
5
10
15
20
5
10
15
20
5
10
15
20
a
b
c
Concentration of
Glucose
Data Table 3: Glucose in wells a-d indicates enzyme activity at various pH
levels
Well
a
b
c
d
pH
3.5
5.0
6.8
11.0
Concentration of Glucose
RESULTS
ANSWER QUESTIONS
Questions:
A. What determines a persons ability to digest lactose?
B. Which of the wells showed a positive result for glucose? Explain the results.
Enzymes: Temperature, pH and Specificity Lab
7
C. Explain why testing for glucose is used to determine the activity of the enzyme
lactase.
D. Explain the experimental conditions for the five different wells.
Questions:
A. Graph the effect of temperature on the activity of the enzyme lactase.
B. What happens when an enzyme is boiled? Is this effect reversible?
C. Based on your experiment results, what is the optimal temperature for lactase
function?
D. Explain what happens as far as the effectiveness of the enzyme at the freezing
temperature.
Can this effect be overcome when the temperature rises?
Questions:
A. Graph the data placing glucose concentrations on the y-axis and the pH values on
the x-axis.
B. What was the effect of pH on the enzyme lactase? Is this true for all enzymes?
Questions:
Faith discussions promote an atmosphere of fellowship and
community (Rom 15:7). Please read the discussion topic
below and a post your comments. Comment and responses
are a minimum of a paragraph consisting of 3-5 lines.
Answer from mostly a human physiology standpoint but any
support from scriptures or faith would be additionally
beneficial.
Read Ps 31:10: My life is consumed by anguish and my years by groaning; my strength
fails because of my affliction and my bones grow weak. This verse describes how
despair and other negative feelings take a toll on our physical well-being. There are
many hypothalamic disorders that result in physical maladies such as wasting away
(cachexia), obesity, sleep disturbances, dehydration, as well as a wide range of
emotional disorders which over time causes the body great harm. Similarly, in Eccl 8:1:
Who is like the wise? Who knows the explanation of things? A persons wisdom
Enzymes: Temperature, pH and Specificity Lab
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brightens their face and changes its hard appearance. Solomon describes how anxiety,
anger, sorrow and frustration can harden ones face, but enjoyment of life and attaining
wisdom will reverse these conditions.
1. Discuss how stress can causes excessive and prolonged cortisol release and the
disease state that may result from this.
2. What character in the bible suffered from severe sleep disturbances? Might this
be related to a hormonal imbalance? Previously, we discussed the viscera of the
abdominopelvic cavity. Splanchnon is the Greek word used to describe various
anatomical, physiological and emotional states. The viscera in the
abdominopelvic cavity have its own blood and nerve supply, aptly named the
splanchnic nerves and the splanchnic circulation. The splanchnic nerves are part
of the autonomic nervous system (ANS) and so the organs they innervate are not
directly under our voluntary control. However conscious emotional states
(anxiety, fear, happiness, etc.) can influence nervous output to the organs. In
addition, the adrenal medulla has the same embryological organ as the
sympathetic division of the ANS, however it releases epinephrine and
norepinephrine as hormones (instead of neurotransmitters) that circulate
throughout the blood stream contacting many organs. Interestingly, in a
theological context, splanchnon in the bible is related to emotions and is always
the responder. The Kardia refers to aspects of the mind and its control over
emotions. Thus, the Kardia is considered the originator.
3. Discuss the connection between mind and body, and how being in tune with
Gods will make us feel comfortable and confident as opposed to how we feel
when out of fellowship with the Lord.
CONCLUSION
SUMMARIZETHESEOBJECTIVESWITHBIGPICTURE
IDEA/12SENTENCESPEROBJECTIVE.
To learn how enzymes work
To understand enzyme specificity
To relate enzyme activity to temperature, pH, and concentration
To understand the role of enzymes in digestion of lactose
Enzymes: Temperature, pH and Specificity Lab
9
REFERENCES
Marieb & Hoehn (2010). Human Anatomy and Physiology.San Francisco, CA: Pearson
Benjamin Cummings
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