Kingdom of Archaebacteria and Kingdom of Eubacteria Overview

Flashcards covering the characteristics, shapes, structures, reproduction, and classification of Eubacteria and Archaebacteria based on Ch.3 lecture notes.

Characteristics of Bacteria

Prokaryotes that are microscopic in the range of micrometers, mostly unicellular (though some form colonies or filaments), and lack nuclear membranes and membrane-bounded organelles.

Coccus

A circular shape of bacteria; can appear in pairs (Diplo-), chains (Strepto-), or clusters (Staphylo-).

Bacillus

A rod-shaped bacterium; variations include Coccobacilli (oval) and Streptobacilli (chains).

Vibrio

A bacterium with a curved rod shape.

Spirochete

A bacterium with a spiral shape.

Capsule/Slimy

A structure that keeps bacteria from drying out and protects them from phagocytosis (engulfing) by larger microorganisms.

Cell Wall (Eubacteria)

Composed of peptidoglycan to provide rigid structure, anchor appendages like pili and flagella, and protect from the outside environment.

Nucleoid

The region of the cytoplasm where chromosomal DNA is located in a prokaryotic cell.

Pili

Small hair-like projections on the outside cell surface that assist in surface attachment and reproduction.

Glycocalyx

The outermost layer in some bacteria, made mostly of polysaccharides and some protein; it serves for adhesion, protection, and as a virulence factor.

Plasmid

Small, extrachromosomal circular DNA structures used for cell division, catabolic enzymes, antibiotic resistance, or genetic exchange.

Binary fission

Asexual reproduction where a single DNA molecule replicates and attaches to the membrane before the cell splits into two genetically identical cells.

Budding

Asexual reproduction where a cell develops a swell or bud that grows and eventually separates from the mother cell.

Fragmentation

Asexual reproduction where walls form within a cell, causing it to separate into several new cells; practiced by species like actinomycetes.

Transformation

Sexual reproduction where a bacterial cell takes up fragments of foreign DNA released by dead or live bacteria to alter its genotype.

Transduction

Sexual reproduction where bacterial genes are carried from one cell to another by phages.

Conjugation

Sexual reproduction involving a cytoplasmic bridge between two cells for the transfer of genetic material from a donor to a recipient.

Gram-positive bacteria

Bacteria that retain purple color in a Gram stain due to a very thick cell wall consisting mainly of peptidoglycans.

Gram-negative bacteria

Bacteria with a thin peptidoglycan layer and a thick outer membrane that release dye readily when washed with alcohol.

Photoautotroph

Organisms that obtain energy from light and use $CO_2$ as a carbon source, such as cyanobacteria.

Chemoautotroph

Self-feeders that obtain energy by oxidizing inorganic chemicals like gaseous hydrogen, sulfur, or nitrogen compounds.

Photoheterotroph

Bacteria that use energy from the sun but rely on organic compounds (like fatty acids or complex carbohydrates) as carbon sources.

Chemoheterotroph

Organisms that use organic compounds for both energy and carbon sources; includes parasites and free-living saprobes.

Obligate anaerobic bacteria

Bacteria that cannot tolerate gaseous oxygen at all and die when exposed to it.

Facultative anaerobes

Bacteria that prefer oxygen but can survive without it.

Endospores

Dormant, extremely durable cells meant for survival (not reproduction) in dry, hot, or frozen environments; can remain virulent for over $1300$ years.

Archaea Membranes

Composed of branched hydrocarbon chains attached to glycerol by ether linkages, allowing them to withstand extreme temperatures and acidity.

Methanogens

Obligate anaerobes that produce methane ($CH_4$) using $H_2$ as an energy source and $CO_2$ as a carbon source.

Extreme Halophiles

Archaea that live in salt concentrations as high as $5$ molar or $25$ percent $NaCl$, such as Halobacterium halobium.

Bacteriorhodopsin

A light-harvesting pigment in the purple membranes of Halobacterium halobium that is chemically similar to rhodopsin in the vertebrate retina.

Hyperthermophiles

Archaea that live at temperatures between $45$ and $110^{\circ}C$; many require elemental sulfur and live in volcanic environments.

Rhizobium

Symbiotic bacteria found in the root nodules of white clover that are significant to the ecosystem.

Streptomycin

An antibiotic produced by the bacterium Streptomyces griseus.

Bioremediation

The use of bacteria to clear contaminated sites, such as using bacteria to decompose oil compounds in oil pollution.