Question

Which of the following is an example of horizontal gene transfer? a. the transmission of an eye color gene from father to daughter b. the transmission of a mutant gene causing cystic fibrosis from father to daughter c. the transmission of a gene conferring pathogenicity (the ability to cause disease) from one bacterial species to another d. the transmission of a gene conferring antibiotic resistance from a mother cell to its two daughter cells e. all of the above.

Short answer

c. the transmission of a gene conferring pathogenicity (the ability to cause disease) from one bacterial species to another.

Step-by-step solution

Analyzing Options

a and b refer to vertical gene transfer from parent to offspring, not horizontal. Similarly, d talks about the transmission of a gene from a mother cell to its daughter cells which is also a case of vertical transmission. Only c talks about the transfer of a gene from one bacterial species to another, which is a clear instance of horizontal gene transfer. The e option can be ruled out because it claims all options are instances of horizontal gene transfer, which they are not.

Key concepts

Vertical Gene Transfer

Vertical gene transfer refers to the transmission of genetic material from parent to offspring. This process is fundamental to the reproduction of organisms, as it passes genetic traits down through generations. For example, when a parent, be it a human or a bacterium, reproduces, the genes are transferred to its offspring, following a kind of generational line.
This is in contrast to horizontal gene transfer, where genes are transferred between unrelated organisms. Vertical gene transfer occurs with every birth and helps maintain the continuity of species, ensuring that offspring inherit traits from their parents.

• It is the method by which humans inherit eye color or genetic diseases, like cystic fibrosis, from their parents.
• In the bacterial world, vertical transmission occurs when bacterial cells divide and pass on genetic information to new daughter cells.

Understanding vertical gene transfer is crucial because it reveals how certain traits or illnesses can be carried through families or populations.

Bacterial Genetics

Bacterial genetics is the study of how genetic material is structured, transmitted, and expressed in bacteria. Unlike humans, bacteria have a simpler genetic makeup but employ fascinating methods to adapt and evolve.
Bacteria can undergo gene exchange and acquire new traits quickly, aiding them in survival and adaptation, especially under harsh conditions.

• Bacteria's genetic material is typically contained in a single, circular chromosome, as well as smaller DNA circles known as plasmids.
• Their rapid reproduction facilitates quick genetic changes across generations.

Plasmids play a significant role in the adaptability of bacteria, often carrying genes that provide beneficial traits, such as antibiotic resistance. Understanding bacterial genetics is essential, especially in the field of medicine where it helps explain how bacteria develop resistance to antibiotics.

Gene Transmission

Gene transmission is the movement of genetic information from one entity to another. This can occur vertically, from parent to offspring, or horizontally, between non-related individuals. In biological contexts, it is a core mechanism through which traits are passed.
For bacteria, gene transmission is vital for adaptation and survival, allowing them to share traits such as virulence factors or antibiotic resistance.

• Horizontal gene transfer allows for the rapid spread of new traits across bacterial communities.
• Vertical transmission ensures that offspring inherit traits from their parent organism.

In the context of the exercise, understanding the nuances between horizontal and vertical transmission helps identify how diseases can spread or how resistance to antibiotics can be shared among bacteria.

Antibiotic Resistance

Antibiotic resistance is the ability of bacteria to defeat the drugs designed to kill them. This phenomenon makes treating bacterial infections difficult, posing a significant threat to public health. Resistance can arise through mutations in bacterial DNA or be acquired from other bacteria via gene transmission.
Horizontal gene transfer plays a crucial role in the spread of antibiotic resistance. Plasmids, often carrying resistance genes, can move between bacteria, quickly spreading resistance traits throughout bacterial populations.

• Antibiotic resistance can result in longer-lasting infections and complications.
• It is often driven by the misuse or overuse of antibiotics in medicine and agriculture.

To combat antibiotic resistance, it's important to understand how it spreads and take steps to minimize the unnecessary use of antibiotics, ensuring they remain effective for future generations.