Description

In this activity, students will create graphs and develop equations to visualize and model raw data obtained from aging flies.  Aging is an incredibly important area of research, and recent biological advances implicate the intestines in aging pathologies.  Given that the gut harbors an immense amount of an organism’s bacteria and these bacteria levels change with age, this activity will investigate changes in bacterial levels at different time points in an aging organism.  Bacterial levels from only two days, 60 and 80 days old, were collected to minimize costs and the sacrifice of the model organism, the fruit fly.  Model organisms are used in order to conduct informative biological experiments in an ethical, cost effective, and timely manner.  Fruit flies are one of the most common genetic models because of their ease of maintenance, short lifespan, and their genetic similarity to many other organisms, including humans, with fruit flies expressing 75% of human disease-causing genes.  It is well known that bacteria grow proportionally to the number present, which means that they obey an exponential growth model, when provided with unlimited nutrients and space.  Using Excel, students will fit an exponential function to the two known data points. They will also analytically derive the exponential law governing the bacterial growth by finding the coefficient of proportionality and the initial population. This activity involves both statistical analysis and mathematical modeling as well as displaying the usefulness of mathematical models for biological data analysis.

This module was inspired by Dr. Salazar’s research on leaky guts and uses real data obtained in her laboratory.  The research attempts to understand how changes in bacterial levels and types of bacteria as an organism ages may impact the health of the organism, with the ultimate goal of developing future therapies to assist humans to live longer, healthier lives.

Biological Learning Outcomes

• Understand basic background about aging and diseases associated with aging.
• Understand how changes in the intestinal barrier may impact aging.
• Understand that changes in bacteria in the gut may impact intestinal barrier function.
• Understand basic background about bacteria growth changes in the intestines with age.
• Understand the importance of bacteria in the gut for the health of an organism.
• Understand how bacteria can rapidly grow in an exponential manner, under certain circumstances
• Understand mechanism of immune activation that can lead to the production of an antimicrobial response that can slow or halt bacterial growth.
• Understand health implications of bacterial growth or changes in types of bacteria in a gut with age.  

Mathematical Learning Outcomes: At the end of the activity, the students will be able to

• Understand that mathematical and/or statistical analysis must be applied to raw laboratory data in order to make conclusions on the biological observations.
• Understand that when analyzing laboratory data consisting of many trials, the average of the data must be computed prior to any mathematical or statistical analysis.
• Perform statistical analysis to raw biological data.
• Perform data-fitting analysis using trendline in Excel.
• Use the exponential law governing the bacterial growth analytically.

Handouts and Resources:  This teaching module is accompanied by:

• Student handout
• Instructor Notes
• Excel file with the Raw Data and Data Analysis

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