Chapter 26: Bacteria and Archaea

Vocabulary practice flashcards covering the key terms, structural distinctions, metabolic pathways, and ecological impacts of Bacteria and Archaea from Chapter 26.

Bacteria

A domain of single-celled prokaryotic organisms that possess cell walls containing peptidoglycan and a single RNA polymerase composed of five subunits.

Archaea

A domain of single-celled prokaryotes characterized by glycerol-ether lipids in their membranes, cell walls lacking peptidoglycan, RNA polymerase with 13 subunits, and initiation of translation with methionine.

Eukarya

The domain of life comprising single-celled protists and multicellular lineages (animals, plants, fungi) defined by membrane-bound nuclei enveloping DNA and the presence of mitochondria (or ancestors that possessed them).

Peptidoglycan

A carbohydrate-protein polymer found in the cell walls of Bacteria that is absent in the cell walls of Archaea and Eukarya.

Formylmethionine

The specific amino acid used by Bacteria to initiate translation, contrasting with methionine used by Archaea and Eukarya.

Histones

Proteins associated with chromosomal DNA packaging found in Archaea and Eukarya, but absent in Bacteria.

Human Microbiome

The community of microbes that naturally inhabits particular areas of the human body.

Extremophiles

Prokaryotes that thrive in extreme habitats, such as hydrothermal vents, highly acidic or alkaline conditions, subglacial waters, and hypersaline environments.

Germ Theory

The principle stating that many diseases are caused by the presence and actions of specific microorganisms (bacteria, archaea, viruses) within the body.

Koch's Postulates

A set of four criteria established by Robert Koch to confirm the causative agent of a specific infectious disease.

Virulence

The heritable, variable ability of a pathogen to cause disease in a host organism.

Endospores

Tough, thick-walled, dormant bacterial structures containing copies of DNA, RNA, ribosomes, and enzymes that form under environmental stress and resist high temperatures, UV radiation, and antibiotics.

Antibiotics

Molecules produced naturally by certain soil bacteria and fungi that kill bacteria or stop them from growing.

Bioremediation

The use of bacteria and archaea to clean up environments polluted with organic solvents by fertilizing or seeding contaminated sites.

Lateral Gene Transfer

The transmission of genetic information between distinct organisms, enabling the acquisition of new genetic diversity outside of binary fission.

Transformation

A mode of lateral gene transfer in which bacteria or archaea naturally take up environmental DNA that has been released by cell lysis or secretion.

Transduction

A process of gene transfer in which viruses (bacteriophages) package host prokaryotic DNA and inject it into a new recipient cell.

Conjugation

A process of horizontal gene transfer involving direct cell-to-cell contact and the transfer of plasmids or chromosomal pieces through a conjugation tube.

Gram-Positive Bacteria

Bacteria that stain purple in the Gram stain procedure due to a thick cell wall composed extensively of peptidoglycan.

Gram-Negative Bacteria

Bacteria that stain pink in the Gram stain procedure due to a cell wall composed of a thin peptidoglycan layer surrounded by an outer phospholipid bilayer.

Phototrophs

Organisms that utilize light from the sun as their primary source of energy to produce ATP.

Chemoorganotrophs

Organisms that generate ATP by oxidizing organic molecules that possess high potential energy.

Chemolithotrophs

Organisms that synthesize ATP by extracting energy from the oxidation of inorganic molecules.

Autotrophs

Organisms capable of synthesizing carbon-carbon building-block compounds from simple inorganic molecules such as $CO_2$ or $CH_4$.

Heterotrophs

Organisms that acquire complex organic compounds by consuming or absorbing materials synthesized by other organisms.

Fermentation

A metabolic pathway producing ATP without an electron transport chain or external electron acceptor, which is less efficient than cellular respiration.

Bacteriorhodopsin

A light-activated protein used by certain bacteria and archaea to generate a proton gradient across the plasma membrane that drives ATP synthesis via chemiosmosis.

Methanotrophs

Bacteria that utilize methane ($CH_4$) as their primary carbon and energy source.

Methanogens

Archaea that produce methane ($CH_4$) as a by-product of cellular respiration.

Cyanobacteria

A photosynthetic bacterial lineage that was the first to perform oxygenic photosynthesis, releasing molecular oxygen into Earth's oceans and atmosphere.

Oxygen Revolution

The rapid global accumulation of molecular oxygen ($O_2$) in the atmosphere and oceans, driven by cyanobacteria splitting water in oxygenic photosynthesis.

Nitrogen Fixation

The process, performed exclusively by certain bacteria and archaea, of converting inert atmospheric molecular nitrogen ($N_2$) into usable ammonia ($NH_3$).

Anoxic Dead Zone

An aquatic environment severely depleted of oxygen caused when high nitrate runoff triggers massive algal and cyanobacterial blooms, followed by rapid oxygen consumption by aerobic decomposers.