What does it mean that the E. coli bacteria are 'competent'?

What does it mean that the E. coli bacteria are 'competent'?

• A. They produce their own plasmids.
• B. They have been treated with calcium to facilitate DNA uptake.
• C. They are in stationary phase.
• D. They are antibiotic resistant by default.

Answer: (B)

Competence means the bacteria can take up DNA from their environment, enabling transformation. In the lab, E. coli are made competent by treating them with calcium ions, which reduces repulsion between the negatively charged DNA and the cell surface and helps the DNA bind to the membrane. Under the right conditions, a brief heat shock or similar treatment allows the DNA to cross into the cell, so plasmids or other genetic material can be introduced. This makes genetic experiments possible. The other statements describe plasmid production, growth phase, or inherent antibiotic resistance, none of which define the ability to take up external DNA.

Competence means the bacteria can take up DNA from their environment, enabling transformation. In the lab, E. coli are made competent by treating them with calcium ions, which reduces repulsion between the negatively charged DNA and the cell surface and helps the DNA bind to the membrane. Under the right conditions, a brief heat shock or similar treatment allows the DNA to cross into the cell, so plasmids or other genetic material can be introduced. This makes genetic experiments possible. The other statements describe plasmid production, growth phase, or inherent antibiotic resistance, none of which define the ability to take up external DNA.