Bacterial Lab Notes

Conjugation

When one bacterium transfers genetic material to another through a pilus, spreading traits like antibiotic resistance.

Transformation

When a bacterium picks up free DNA from its surroundings (e.g., from dead bacteria), which can integrate and provide new abilities like antibiotic survival, or mix with its own genes.

Transduction

When a bacteriophage (virus) accidentally carries DNA from one bacterium to another, causing genetic changes upon infection.

Mutation

A random change in an organism

s DNA, happening naturally or due to environmental factors, which can be helpful, harmful, or have no effect.

Destruction/Inactivation

When bacteria use special enzymes to break down or disable antibiotics, making the bacteria resistant.

Efflux

When bacteria use tiny pumps in their cell walls to push antibiotics out before they can do damage, resisting the antibiotics.

Gene

A small piece of DNA that contains instructions for making a protein, which dictates how an organism looks, grows, and functions.

Plasmid

A small, circular piece of DNA in bacteria, separate from their main chromosome, often carrying extra genes like those for antibiotic resistance, and capable of moving between bacteria.

Naked DNA

DNA that is not inside a cell or protected, floating freely in the environment, which bacteria can take in via transformation.

Pilus

A thin, hair-like structure on the surface of some bacteria, used for attachment to surfaces or other cells, and forming a bridge to share DNA during conjugation.

Bacteriophage

A virus that infects bacteria, injecting its DNA and potentially using the cell to make more viruses or transfer bacterial DNA between cells.

Ampicillin (Amp)

An antibiotic that kills bacteria by stopping them from making strong cell walls. Bacteria with the ampicillin resistance gene (Amp ) produce beta-lactamase to break down ampicillin.

Streptomycin (Str)

An antibiotic that attaches to bacteria's ribosomes, blocking protein production and killing the bacteria. Bacteria with the streptomycin resistance gene (Str ) have a mutation or enzyme protecting their ribosome.

LB (Luria Broth or Lysogeny Broth)

A nutrient-rich food source for bacteria, containing yeast extract, tryptone, and salt. When mixed with agar, it forms a solid LB plate for bacterial growth.

Fertility (F) Plasmids

Plasmids that carry genes enabling bacteria to form a sex pilus for DNA transfer during conjugation, controlling the ability to share genetic material.

Resistance (R) Plasmids

Plasmids that contain genes making bacteria resistant to antibiotics or other harmful substances, allowing for rapid spread of antibiotic resistance.

Col Plasmids

Plasmids that possess genes producing bacteriocins, proteins that kill or inhibit the growth of other bacteria, thus providing a competitive advantage.

Degradative Plasmids

Plasmids that contain genes helping bacteria break down unusual substances like oil or pesticides for food or energy.

Virulence Plasmids

Plasmids that help bacteria cause disease.

Fimbriae (Attachment Pili)

Short, hair-like pili that help bacteria stick to surfaces (e.g., cells, medical equipment) but do not transfer DNA.

Sex Pili (Conjugation Pili)

Longer pili used during conjugation to connect two bacteria and form a bridge for DNA (usually plasmid) transfer.

Type IV Pili

Motile pili that aid bacteria in crawling along surfaces via twitching motility, attachment, and sometimes infection.

Curli Pili

Pili that help bacteria form biofilms (slimy layers) that facilitate sticking together and provide protection against antibiotics or the immune system.