Bacterial Genetics and Taxonomy Flashcards

Vocabulary flashcards covering bacterial horizontal gene transfer, transformation, conjugation, transduction, and bacterial taxonomy principles.

Genotype

The specific combination of genes that an organism possesses.

Phenotype

The physical manifestation of an organism's genes.

Horizontal transmission

The passing of genetic information from one bacterial cell to another through means other than reproduction.

Frederick Griffith

A microbiologist who in $1928$ worked with $Streptococcus$ and discovered the transforming principle.

Capsule

A cell structure that helps bacteria hide from the host immune system, making the pathogen more effective and potentially lethal.

Transforming principle

A term used by Griffith to describe the substance from dead cells that transformed living rough cells into smooth cells.

Transformation

The process where bacterial cells absorb fragments of DNA from their environment and incorporate them into their own chromosomes through homologous recombination.

Competence

The term used to describe bacteria that are capable of performing transformation.

Homologous recombination

A molecule combination mechanism that works more effectively if two DNA sequences are very similar.

Plasmid

Small circular pieces of DNA that exist and replicate separately from the bacterial chromosome.

F plasmid

The fertility plasmid that contains genes allowing a bacterial cell to make an f pilus for conjugation.

F plus ($F+$) cell

A bacterial cell that possesses the F plasmid.

F pilus

An attachment structure used by an $F+$ cell to connect to an $F-$ cell for the transfer of DNA.

Conjugation

The transfer of genetic material between bacterial cells through a pilus connection.

High frequency recombinant (Hfr)

A cell that has patched its F plasmid into its own chromosome, allowing it to transfer chromosomal fragments during conjugation.

Transduction

Horizontal gene transfer mediated by a virus that accidentally packages bacterial DNA into a protein shell and injects it into a new cell.

Carolus Linnaeus

The scientist credited with developing binomial nomenclature and some of the earliest work in the taxonomy of living things.

Binomial nomenclature

A worldwide system for naming organisms using a capitalized Genus name and a lowercase species name, both of which are italicized or underlined.

Frederick Cohn

A German bacteriologist who worked on the taxonomy of bacteria using phenotypes such as cell shape and arrangement.

Carl Woese and George Fox

Microbiologists who proposed the domain level of taxonomy and a new way to define species using small ribosomal subunit sequences.

Monera

The single kingdom that previously held all prokaryotes (bacteria and archaea) before the implementation of the domain system.

Biological species concept

A definition of species as organisms that can breed and produce fertile offspring, which is not applicable to bacteria.

Small ribosomal subunit identity

The taxomonic standard where two organisms are the same species if they share $97\%$ identity or better in their small ribosomal subunit RNA sequence.

Genomic DNA identity standard

The standard where two organisms belong to the same species if their genomic DNA is $95\%$ identical or better.

DNA-DNA hybridization standard

An older method for species determination requiring $70\%$ or higher hybridization.

Strains

Subspecies groups within a species of bacteria distinguished by specific characteristics.

Morphovars

Bacterial strains distinguished by visible physical differences, such as the rough versus smooth streptococcus.

Biovars

Bacterial strains distinguished by metabolic differences, such as the ability to synthesize histidine.

Cerebars

Bacterial strains distinguished using serology and antibodies that recognize specific molecular shapes.

O antigen

The long chain of sugars in lipopolysaccharide (LPS) that sticks up from the core oligosaccharide and serves as a target for antibodies.