L2 - Bacteria and Archaea Flashcards

Comprehensive vocabulary flashcards covering bacterial naming, structures, arrangements, staining techniques, secretion systems, and the characteristics of Archaea based on the lecture transcript.

Nomenclature

A binomial system of naming microorganisms using Genus (capitalized) and species (lowercase), both of which are italicized or underlined.

Biofilms

Groups of bacteria that cooperate together and secrete slime to enhance survival and protect against harmful substances like antibiotics.

Quorum sensing

A process by which bacteria act as a group rather than as individual cells.

Thiomargarita namibiensis

A large bacterium with a size ranging from $100$ to $750\,\mu{m}$.

Mycoplasma

Bacteria that naturally lack a cell wall, measure $0.15$ to $0.30\,\mu{m}$, and have membranes stabilized by sterols.

Pleomorphism

Variation in size and shape among cells of a single bacterial species.

Coccus

A spherical or ball-shaped bacterial cell.

Bacillus

A bacterial cell that is cylindrical or rod-shaped.

Vibrio

A rod-shaped bacterium that is singly curved.

Spirillum

A bacterium having a slightly curled or spiral-shaped body.

Spirochete

A spiral cell that contains periplasmic flagella and resembles a coiled hair.

Sarcina

A cubical packet of $8$, $16$, or more cocci cells.

Palisades

An arrangement of bacilli where cells remain partially attached and fold back, creating a side-by-side row.

Peptidoglycan

A unique macromolecule found in most bacterial cell walls composed of glycan chains cross-linked with short peptides.

Lipopolysaccharide (LPS)

An endotoxin found in the outer membrane of Gram-negative bacteria that is highly immunogenic and can cause septic shock.

Mycolic acid

A very-long-chain fatty acid found in the cell walls of Mycobacterium and Nocardia that contributes to pathogenicity.

Porin proteins

Proteins that span the outer membrane and regulate the entrance of molecules, acting as a defense against some antibiotics.

Chemotaxis

Bacterial movement in response to chemical signals, characterized by positive or negative direction.

Axial filament

Also called periplasmic flagella; internal threads in spirochetes that impart a corkscrew motion to the cell.

Type III Secretion System (T3SS)

A system structurally similar to flagella used by Gram-negative pathogens to translocate protein effectors into host cells.

Type VI Secretion System (T6SS)

A system used by bacteria to kill other bacteria for resources, acting like a bolt gun to shoot warheads into target cells.

Plasmid

Double-stranded, non-essential circular DNA that confers protective traits and is used in genetic engineering.

Svedberg (S) units

A measurement of the relative size of cell parts based on sedimentation during centrifugation.

$70S$ Ribosome

The size of bacterial ribosomes, composed of a $50S$ large subunit and a $30S$ small subunit.

Endospore

A dormant, inert body formed by some bacteria to withstand hostile conditions and ensure survival.

Methanogens

Archaea that convert $CO_2$ and $H_2$ into methane gas ($CH_4$).

Extreme halophiles

Archaea that require high salt concentrations (up to $36\%\,NaCl$) to grow.

Hyperthermophiles

Archaea adapted to flourish at temperatures between $80^{\circ}C$ and $113^{\circ}C$.