Generalized transduction is a process of horizontal gene transfer in which a bacteriophage incorrectly packages a random fragment of the host bacterium's degraded chromosome into its capsid instead of viral DNA during the lytic cycle. When this phage infects a new bacterial cell, it injects the previous host's DNA. This asexual gene transfer can lead to DNA recombination, providing the recipient bacterium with new genes, such as those for antibiotic resistance or sugar metabolism.

Google

Viral transduction is a process of horizontal gene transfer where a bacteriophage transfers DNA from one host bacterium to another during sequential infections. This asexual exchange of genetic information can result in DNA recombination, potentially introducing new genes, such as sugar-metabolizing or antibiotic-resistance genes, to the recipient bacteria, and playing a key role in bacterial evolution.

Viral Transduction

During the lytic cycle, a virulent bacteriophage takes over the host bacterial cell, replicates its viral genome, synthesizes proteins to assemble new phages, and ultimately destroys the host cell by cell lysis to release progeny viruses.

Lytic Cycle

https://openstax.org/details/books/microbiology/

Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

OpenStax Microbiology Textbook

Generalized Transduction

Specialized transduction is a horizontal gene transfer mechanism that occurs at the end of the lysogenic cycle when a prophage undergoes induction and enters the lytic cycle. During excision from the host chromosome, the phage may mistakenly remove adjacent bacterial DNA from one or both ends of the integration site. This specific piece of host DNA is packaged with the viral DNA into the capsid and transferred to a new host, where it can recombine and convey new characteristics.

Specialized Transduction

Biosynthesis is the stage of bacteriophage infection where the virus degrades the host chromosome using virus-encoded endonucleases. The virus then hijacks the host cell's machinery to replicate, transcribe, and translate key viral components (such as capsomeres, sheaths, base plates, tail fibers, and viral enzymes) for assembling new viruses, with polymerase genes expressed early and capsid and tail proteins expressed later in the cycle.

Biosynthesis of Bacteriophage

The replication steps for bacteriophages generally include attachment to the host, entry or penetration of the viral genome, replication and synthesis of viral components (biosynthesis), assembly of new phages (maturation), and release of progeny virions (lysis).

Steps of Bacteriophage Replication

During attachment, the first stage of the lytic cycle, a bacteriophage interacts with specific surface receptors on the host bacterium (such as lipopolysaccharides and OmpC proteins). Phages typically exhibit a narrow host range, restricting infection to particular bacterial species or specific strains.

Attachment of Bacteriophage

Penetration is the second stage of the lytic cycle, where the bacteriophage contracts its tail sheath like a hypodermic needle to inject its viral genome through the host cell wall and membrane, while the phage head and other components remain outside the cell.

Penetration of Bacteriophage (Lytic Mechanism)

Maturation is the stage of the bacteriophage lytic cycle in which newly synthesized viral components are assembled to form complete, new phage particles within the host cell.

Maturation of Bacteriophage

Lysis is the final stage of the bacteriophage replication cycle, where the bacterial cell wall is disrupted by phage proteins such as holin or lysozyme. This disruption causes the host cell to burst, releasing the newly assembled progeny viruses into the environment to infect new cells.

Learn Before

Related