Lab 9: Bacterial Transformation Flashcards
What are plasmids?
Small circular, self-replicating DNA molecules that exist separately from the bacterial chromosome. Bacteria pick them up from their surroundings though transformation.
Name three differences between chromosomal DNA and plasmid DNA?
Chromosomal DNA:
- Located in the chromosomes in the nucleus or nucleoid region
- Larger in size
- One copy per cell
- Contains essential genetic info for growth, development, and reproduction
- Replicates during the cell cycle
-Passed from parent cells to daughter cells during cell division
Plasmid DNA:
- Located in the cytoplasm, outside the chromosomal DNA
- Smaller, circular shaped
- Multiple copies per cell
- Contain nonessential genes that provide specific traits
- Replicated independently
- Transferred between cells via conjugation, transformation, or transduction.
What is bacterial transformation?
A process by which bacterial cells take up foreign DNA molecules from their environment and incorporate them into their own genome. Commonly used in genetic engineering to introduce specific genes into bacterial cells for studying gene function.
What is a gene? Explain how a gene shows its effect.
A gene is a sequence of DNA that codes for a specific product. They show its effect through the process of gene expression, which involves the transcription of DNA into messenger RNA (mRNA) AND translation of mRNA into a functional protein. The specific protein produced by a gene ultimately determines the phenotype of an organism.
What is a pGLO plasmid?
A pGLO plasmid is a type of plasmid DNA that contains genetic elements such as
- A gene for the green fluorescent protein (GFP) that allows for the expression of a fluorescent protein in cells for visualization
- An ampicillin resistance gene (amp) that provides bacteria with abx resistance
- An arabinose operon that controls the expression of the GFP gene in the presence of arabinose
Explain how bacteria can gain antibiotic resistance.
Bacteria can acquire resistance through spontaneous mutations in their DNA. These mutations may affect genes involved in antibiotic target sites, antibiotic uptake, or antibiotic inactivation. Mutations that confer resistance to antibiotics provide a selective advantage to the bacteria in environments where antibiotics are present.
Explain how the expression of a gene can be induced.
The expression of a gene, specifically the green fluorescent protein (GFP) gene, can be induced by the presence of a specific molecule in the growth medium. The pGLO plasmid contains the GFP gene under the control of a promoter that is activated in the presence of arabinose, a sugar molecule.
Briefly explain the pGLO plasmid experiment.
The pGLO plasmid experiment involves transforming E. coli bacteria with a plasmid containing the GFP gene and an ampicillin resistance gene. After heat shock treatment, the bacteria are plated on LB agar plates with ampicillin and arabinose. Those that take up the plasmid express GFP and resist ampicillin. Upon incubation, transformed bacteria appear fluorescent green under UV light, demonstrating successful gene expression. This experiment illustrates bacterial transformation, gene regulation, and biotechnological applications.
