Gene Bacteria

Domains Archaea and Bacteria

domains of living organisms to which all prokaryotes belong; includes bacteria (eubacteria and archaebacteria) and blue-green algae (cyanobacteria).

Pathogenic

any organism that is capable of causing disease.

Nucleoid

vaguely defined region in bacteria that contains most of the hereditary material; takes the place of the nucleus.

Bacterial Chromosome

main genetic material in bacteria; it consists of a single, long, circular molecule of DNA which is not wrapped around supporting proteins and which contains most of the organism’s genes.

Plasmids

small, circular DNA molecules that exist separately from the bacterial chromosome, replicate on their own, and provide useful advantages even though bacteria don’t need them to survive.

Binary Fission

a simple method of asexual reproduction used by most bacterial species; it is a form of cell division, but not mitosis, and involves one parent cell splitting into two identical daughter cells; this type of fission is responsible for the rapid growth rates of bacteria.

Horizontal Gene Transfer

process in which genetic material is transmitted between organisms that are not parent and offspring; instead, the two organisms are usually unrelated, and often different species.

Transformation

process in which free DNA is taken up by a particular cell and then integrated into the receiving cell’s genome.

Conjugation

transfer of DNA from a donor cell to a recipient cell by direct cell-to-cell contact; plasmids mediate this process.

Transduction

process in which bacterial DNA is transferred from a donor cell to a recipient cell by means of a bacteriophage.

Bacteriophage (=phage):

a virus that attacks and infects bacterial cells.