Horizontal Gene Transfer Study Set

Vocabulary-style flashcards covering Horizontal Gene Transfer mechanisms (transformation, conjugation, and transduction) and their applications.

Transformation

The process of importing free DNA into bacterial cells.

Competent

A state in which bacterial cells are capable of natural transformation.

Artificial Transformation

The use of chemical methods ($CaCl_2$) or electrical methods (electroporation) to perturb the membrane for DNA import.

Competence Factor (CF)

A secreted signaling molecule that accumulates via quorum sensing to induce a genetic program for transformation in Gram-positive bacteria.

SigH (Sigma factor H)

A transcription factor stimulated by ComE-P that directs the transcription of transformasome components.

Transformasome

A protein complex that facilitates the uptake of DNA in Gram-positive bacteria.

Gram-negative Transformation

A process that does not use competence factors or transformasomes and is typically sequence-specific, limiting gene exchange between genera.

Conjugation

A method of gene transfer that requires the presence of special transferable plasmids and cell-to-cell contact.

F factor (Fertility factor)

A transferable plasmid in E. coli that contains the genes necessary for pilus formation and DNA export.

F+ Cell

The genetic donor cell during conjugation.

F- Cell

The recipient cell during conjugation.

Sex Pilus

A structure from an F+ plasmid donor that attaches to receptors on a recipient cell and contracts to draw the cells together.

Relaxosome

A bridge and protein complex formed between donor and recipient cells that facilitates the transfer of DNA.

oriT (Origin of Transfer)

The specific site (nic site) on the F factor where DNA is nicked to begin the transfer process.

Relaxase

The enzyme that nicks the DNA at the $oriT$ site to initiate DNA transfer.

Neisseria gonorrhoeae

An example of a bacterium that contains human-derived sequences, demonstrating DNA transfer between domains.

Agrobacterium tumefaciens

A bacterium that invades plant cells and transfers a tumor-inducing plasmid (Ti) via conjugation.

Ti plasmid

A tumor-inducing plasmid transferred by Agrobacterium tumefaciens to plant cells, stimulating hormone production and cell division.

Crown Gall Disease

A condition caused by Agrobacterium tumefaciens resulting in round tumor growths on stems or roots that interfere with nutrient and water movement.

Agrobacterium radiobacter

A control bacteria used as a treatment for roots to combat Crown Gall Disease.

Callus

A clump of gene-altered plant cells that form after surviving antibiotic exposure in the production of edible vaccines.

Transduction

The process in which bacteriophages carry host DNA from one bacterial cell to another.

Generalized Transduction

A type of transduction that can transfer any gene from a donor to a recipient cell.

Specialized Transduction

A type of transduction that can transfer only a few closely linked genes between cells.

P22 Phage

A specific bacteriophage that infects a host cell and can package host DNA into capsid heads during generalized transduction.