Question

Resistance to antibiotics is a well-recognized medical problem. What mechanisms account for a bacterium’s ability to increase its genetic variability and thus adapt itself to different antibiotics? A. Binary fission B. Conjugation C. Transduction D. Both (B) and (C)

Short answer

The correct answer is D. Both Conjugation and Transduction.

Step-by-step solution

- Understanding Binary Fission

Binary fission is a form of asexual reproduction in bacteria where a single cell divides into two genetically identical daughter cells. It does not introduce genetic variability.

- Understanding Conjugation

Conjugation is a process where genetic material is transferred from one bacterium to another through direct contact. It involves the transfer of plasmids, which can carry antibiotic resistance genes, thus increasing genetic variability.

- Understanding Transduction

Transduction is the process by which a bacteriophage (a virus that infects bacteria) transfers genetic material from one bacterium to another. This can introduce new genetic information, including antibiotic resistance genes, into a bacterium.

- Analyzing the Correct Answer

Based on the explanations, both conjugation and transduction contribute to increasing a bacterium's genetic variability, allowing it to adapt to different antibiotics.

- Conclusion

The mechanisms that account for a bacterium’s ability to increase its genetic variability and adapt to different antibiotics are Conjugation and Transduction.

Key concepts

Conjugation

Conjugation is a vital process in bacterial genetic variability. It involves the direct transfer of DNA from one bacterium to another through physical contact. Usually, this contact is made via a structure called a pilus, which acts as a bridge between the cells.

During conjugation, plasmids are often exchanged between bacteria. Plasmids are small, circular pieces of DNA that exist independently of the bacterial chromosome. They frequently carry genes that confer antibiotic resistance, which means that when one bacterium receives a plasmid via conjugation, it can gain resistance to certain antibiotics.

This exchange of genetic material helps bacteria adapt quickly to their environments. For example, in a population of bacteria exposed to an antibiotic, conjugation can rapidly spread resistance genes, making the entire population more likely to survive.

Transduction

Transduction is another method by which bacteria can gain genetic variability. This process involves bacteriophages, which are viruses that specifically infect bacterial cells.

When a bacteriophage infects a bacterium, it may accidentally incorporate some of the host bacterium's DNA into its viral particle. When this phage goes on to infect another bacterium, it can transfer these bacterial genes to the new host. This can include genes for antibiotic resistance.

This transfer of genes can provide the recipient bacterium with new capabilities, helping it adapt to its environment. Unlike conjugation, transduction doesn't require direct contact between bacteria, allowing for genetic material to be spread even among bacteria that are not in close proximity to each other.

Antibiotic Resistance

Antibiotic resistance is a major concern in modern medicine, making infections harder to treat. This resistance happens when bacteria evolve mechanisms to withstand the effects of antibiotics designed to kill them.

Resistance can be acquired through different genetic mechanisms, such as mutations in bacterial DNA and the acquisition of resistance genes through conjugation or transduction.

These genetic changes can lead to:

• Efflux pumps that remove antibiotics from the cell
• Enzymes that degrade antibiotic molecules
• Changes in target molecules so the antibiotic cannot bind effectively

As bacteria with resistance genes survive antibiotic treatments, they multiply and spread these genes, making entire bacterial populations more resistant over time.

Thus, understanding mechanisms like conjugation and transduction is critical for developing strategies to combat antibiotic resistance.