Description
Discussion Board: Using the attached file: Got Lactase? Experimental Design analyze the Materials and Methods used, and the Results obtained. (I need you please to do the Initial postand also the summery post )
Are there any changes that should be made to this procedure?
Do you feel confident about the quality of the data collected?
Identify at least one change that should be made to this procedure and post this in the Discussion Board titled, “Got Lactase? Improvement of Experimental Design”. There is an important step that should be included, so work with your peers to identify this key addition to the procedure.
Initial post DUE by Wednesday @ 11:59 pm
In your initial post, answer the following questions:
Are there any changes that should be made to this procedure?
Do you feel confident about the quality of the data collected?
Identify at least one change that should be made to this procedure and why changing the procedure in this way would be better experimental design.
Important instructions for your initial post:
Your initial post must be written in complete sentences.
Your initial post must be at least 200 words long.
The initial post must be completed by Sunday or points will be deducted.
TWO Reply posts to peers DUE by Sunday @ 11:59 pm
Two peer reply posts are needed to TWO different students. In your reply to your peers write a substantive response to their original post that provides positive feedback about the information you agree with and constructive suggestions for a different way to interpret the information you disagree with. Do not repeat information you already wrote in your original post. This is where you communicate with your peers about the experimental design flaws and how to fix them.
**If a student’s initial post already has two peer replies, move on to another student’s initial post to respond. This will ensure that all students get feedback from their peers!**
Important instructions for your response posts:
Reply posts must be within the parent post!
Your response post must be written in complete sentences.
Your response post must be at least 50 words long.
Criteria for Success:
Here is a checklist of characteristics of successful work.
Initial Post: 15 points
Two replies to peers: 10 points (5 points each)
Unformatted Attachment Preview
Got Lactase? Improvement of Experimental Design
This activity is adapted from HHMI BioInteractive – “Milk: How Sweet is it?” – https://www.biointeractive.org/classroomresources/milk-how-sweet-it
Learning Objectives:
•
•
Plan the steps in an experimental procedure, including controls.
Interpret tests for the presence of glucose in a sample using glucose test strips.
1. View the video “The Making of the Fittest: Got Lactase? The Co-evolution of Genes and
Culture”.
2. Read the Introduction.
3. Analyze data and experimental design for Lactase Persistence.
4. Contribute to discussion board.
INTRODUCTION
In the film, The Making of the Fittest: Got Lactase? The Co-Evolution of Genes and Culture, Dr.
Dallas Swallow determines that Dr. Spencer Wells can digest lactose, the main sugar in milk, by
having him rapidly drink a liter of milk and then measuring glucose levels in his blood. Why
would measuring blood glucose levels tell you whether someone can digest lactose?
In the intestine, the lactose in milk is broken down into glucose and galactose by the enzyme
lactase. These two simpler sugars are absorbed from the intestine into the bloodstream. As a
result, if the lactase enzyme is present, blood glucose levels increase within 20 to 60 minutes of
drinking milk.
Figure 1: Lactase Enzyme Reaction
Not all human adults, however, produce lactase—in fact, most people worldwide don’t. They
are referred to as lactose intolerant or lactase nonpersistent. When lactose-intolerant
individuals drink milk, the lactose passes undigested through the small intestine into the large
intestine and may cause gas, bloating, and sometimes diarrhea. A significant minority of adults
worldwide can digest milk without any problems; they are lactose tolerant or lactase
persistent.
Recall that lactase is an enzyme that breaks down lactose. If an individual is producing lactase,
it would be present in their intestinal fluid.
Materials and Methods:
1.
2.
3.
4.
A sample of intestinal fluid was collected from 4 patients.
5 mL of each patient’s intestinal fluid was placed in a labeled test tube.
5 mL of milk was added to the 5 mL sample of intestinal fluid from each patient.
Once the milk was added, each sample was tested at 2 minutes and again at 7 minutes
with glucose test strips.
5. Glucose test strips were analyzed using Figure 2.
Glucose test strips change color depending on the concentration of glucose in the sample. See
the color chart below for the colors and corresponding concentrations of glucose (in mg/dL).
The colors from left to right will be referred as: yellow, light green, grass green, dark green,
forest green.
Figure 2: Glucose test strip colors and glucose concentration
Results:
Table 1: Patient Results
Test Tube
Test Tube Contents
2 minutes: Glucose
strip color
7 minutes: Glucose
strip color
Positive Control
Lactase Enzyme + Milk
Dark green
Dark Green
Negative Control
Water + Milk
Yellow
Yellow
Patient 1
Sample 1 + Milk
Light Green
Light Green
Patient 2
Sample 2 + Milk
Grass Green
Dark Green
Patient 3
Sample 3 + Milk
Yellow
Yellow
Patient 4
Sample 4 + Milk
Dark Green
Dark Green
Conclusions:
Discussion Assignment: Analyze the Methods used, and the Results obtained. Are there any
changes that should be made to this procedure? Do you feel confident about the quality of the
data collected? Identify at least one change that should be made to this procedure and post
this in the Discussion Board titled, “Got Lactase? Improvement of Experimental Design”. There
is an important step that should be included, so work with your peers to identify this key
addition to the procedure.
Discussion Board Posts:
Initial post DUE by Wednesday @ 11:59 pm
In your initial post, answer the following questions:
• Are there any changes that should be made to this procedure?
• Do you feel confident about the quality of the data collected?
• Identify at least one change that should be made to this procedure and why changing the
procedure in this way would be better experimental design.
Important instructions for your initial post:
• Your initial post must be written in complete sentences.
• Your initial post must be at least 200 words long.
• The initial post must be completed by Sunday or points will be deducted.
TWO Reply posts to peers DUE by Sunday @ 11:59 pm
Two peer reply posts are needed to TWO different students on TWO different days. In your reply to
your peers write a substantive response to their original post that provides positive feedback about the
information you agree with and constructive suggestions for a different way to interpret the information
you disagree with. Do not repeat information you already wrote in your original post. This is where you
communicate with your peers about the experimental design flaws and how to fix them.
**If a student’s initial post already has two peer replies, move on to another student’s initial post to
respond. This will ensure that all students get feedback from their peers!**
Important instructions for your response posts:
• Reply posts must be within the parent post!
• Your response post must be written in complete sentences.
• Your response post must be at least 50 words long.
Summary Post DUE Sunday @ 11:59 pm
In your summary post, you will complete a 3-2-1 analysis. In this analysis, you will share
•
•
•
three things you learned about lactase and experimental design from the activity,
two things that interested you, and
one thing your group would change in the experiment.
Important instructions for your summary post:
• Your summary post must be written in complete sentences.
• Your summary post must be at least 100 words long.
• The summary post must be completed by Sunday or points will be deducted.
Criteria for Success:
Here is a checklist of characteristics of successful work.
•
•
•
Initial Post: 10 points
Two replies to peers on two different days: 10 points (5 points each)
Summary post: 5 points
Discussion Board Rubric: Check the rubric in Canvas
Use this to check your posts before submitting.
Level
Points
Discussion
Activity
Proficient
25
Student made
substantive
contribution to
discussion. Added
new information or
asked/answered
questions two or
more times.
Competent
15
Student made some
contribution to
discussion. Added
new information or
asked/answered
questions 2 times.
Improving
5
Student made one
contribution to
discussion. Added
new information or
asked/answered
questions 1 times.
Limited
0
Student did not
participate or added
no new
information/answers
to the discussion. “I
agree” type posts.
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