Lab 1
lab 1
Title: Eau that smell A synthetic biology lab for high school using BioBuilder
Objectives
By the conclusion of this laboratory investigation, the student will be able to:
- Explain how synthetic biology as an engineering discipline differs from genetic engineering.
- Explain the population growth curve of bacteria.
- Define and properly use synthetic biology terms: parts, device, inverter.
- Define and properly use molecular genetics terms: promoter, ribosome binding site, open reading frame, terminator, plasmid,
- Culture bacteria using proper microbiology methods.
- Measure the growth of a bacterial population.
Introduction
For the 2006 iGEMcompetition, MIT students designed eau d’ e coli, E. coli that smell like bananas when their population is in the stationary phase. They did this by inserting device that contains a stationary phase sensitive promoter coupled to a banana smell device, a device that contains a ribosome binding site (RBS), an open reading frame (ORF) that codes for the ATF1 enzyme and terminator sequences. The ATF1 enzyme converts isoamyl alcohol to isoamyl acetate, the molecule that gives bananas their characteristic smell.
It has been suggested that a device that generates the banana smell during the bacteria’s log (or exponential) phase of population growth will be helpful. There are two ways to accomplish this. Both methods will continue to use the banana smell device but alter the function of the promoter. One method involves coupling the banana smell device to a new part, a log phase promoter. The other method involves using the same promoter but adding an inverter. Synthetic biologists have constructed these devices for us and transformed bacteria with them.
We have been sent three different E. coli colonies. Each contains a different device :
- The original eau d’ Coli device
- The banana smell generator coupled to the log phase promoter
- The original eau d’ Coli device but with an inverter added.
Our task will be to grow these bacterial populations and test for the banana smell as the population moves through the log phase and into the stationary phase. We will determine the population growth by using a Spec 20 to measure the density of the bacteria in liquid culture. As the population increases we can assess the increasing banana smell.
Data Table
In your lab notebook, you will need to construct a data table as shown below for each of the samples. (These may be provided)
SAMPLE________________________________
| Time | OD420 | OD550 | OD600 | group cells/ml | class mean cells/ml | Banana smell (+/-) |
|---|---|---|---|---|---|---|
| Initial | ||||||
| 20 minutes | ||||||
| 40 minutes | ||||||
| 60 minutes | ||||||
| 80 minutes | ||||||
| 120 minutes |
Procedure
Part 1: Preparing the bacterial cultures:
Part 2: Measuring bacterial population growth:
Lab Report
As you write, be sure to define and properly use all highlighted terms throughout the introduction and other parts of the lab.
Introduction:
- Provide a brief introduction describing the field of synthetic biology.
- Briefly describe the purpose of the lab. What are we trying to do here? Why are we using optical density to measure the population?
- Presume that a reader of your lab report has not read the assignment.
- Explain each phase of the bacterial population growth curve.
Methods:
- You do not have to rewrite the procedure.
- Explain why you did each step of the protocol.
Results:
- Present the data tables in clear format.
- Draw population growth curves of the class mean data for each sample. Indicate on each curve when you could smell bananas.
Discussion:
- Describe the results: Were we able to measure the population growth? Were we able to smell bananas?
- Analyze the data: Be sure to discuss how each part of the experiment adds to your conclusion.
- Discuss errors and other reasons for data variability.
- How might we try to change this system so that we can quantify the banana smell? Would we be better off using a different kind of signal? If so, what would you suggest?
- If you could construct a genetic system, what might you construct? What would you need to do?
Citations and references:
- Be sure these are of good quality.
- Embed citations.
- Follow proper reference format.
