Microbial Diversity, Metabolism, and Immunology

Comprehensive vocabulary flashcards covering microbial diversity, cellular metabolism, antibiotic mechanisms/resistance, fungal biology, and the basics of innate immunity based on lecture materials.

Prokaryotes

Microbes belonging to Domain Bacteria and Domain Archaea that share common traits but exhibit great diversity, colonizing every habitat on Earth.

Cyanobacteria

Oxygenic photoautotrophic prokaryotes that produce oxygen and contain chlorophyll; they are the ancestors of plant chloroplasts.

Chemolithotrophs

Also known as chemoautotrophs, these organisms obtain energy from the oxidation of inorganic compounds (litho = rocks).

Chemoorganotrophs

Also known as chemoheterotrophs, these organisms obtain energy and carbon from organic compounds.

Thylakoids

Specialized systems of extensively folded lamellae packed with chlorophyll and photosynthetic proteins found in certain Gram-negative bacteria like cyanobacteria.

Carboxysomes

Protein microcompartments that encapsulate the enzyme RuBisCO to concentrate $CO_2$ and improve the efficiency of carbon fixation.

Gas vesicles

Structures that collect metabolic gases like $H_2$ and $CO_2$ to help aquatic microbes maintain buoyancy for optimal light access.

Heterocysts

Specialized cells in many cyanobacteria used specifically for the process of fixing $N_2$ (nitrogen fixation).

Adenosine triphosphate (ATP)

The most common energy molecule in cells used for safe energy storage and release during catabolism.

Substrate-level phosphorylation

A mechanism of ATP generation where a hydrolysis reaction releases enough energy to drive the phosphorylation of ADP to ATP directly.

Oxidative phosphorylation

The synthesis of ATP powered by an electrochemical gradient of protons (Proton Motive Force) generated by the Electron Transport System.

Proton Motive Force (PMF)

An electrochemical gradient of protons that drives ATP synthesis at the ATP synthase and powers functions like flagella rotation.

Fermentation

A non-respiration-based mechanism to generate ATP via glycolysis in the absence of oxygen, using organic molecules as terminal electron acceptors.

Biofilms

Complex assemblies of microbial communities attached to surfaces and encased in a sticky extracellular polysaccharide (EPS) matrix.

Quorum sensing

A communication system where bacteria produce and detect chemical signals called autoinducers to coordinate group behavior based on population density.

Selective toxicity

The principle of using a drug to harm or kill a target pathogen without causing significant harm to the host organism.

Bactericidal

A characteristic of antibiotics that indicates they actively kill the target bacteria.

Bacteriostatic

A characteristic of antibiotics that indicates they inhibit the growth of bacteria rather than killing them outright.

Minimum Inhibitory Concentration (MIC)

The lowest concentration of an antibiotic that prevents the visible growth of a target microorganism in vitro.

Synergistic effect

A combined effect of two drugs that is greater than the sum of their individual effects, effectively boosting each other's power.

Beta-lactamase

A secreted degradative enzyme produced by bacteria that destroys beta-lactam antibiotics, serving as a primary resistance strategy.

Virions

Inanimate viral particles as they exist outside of a host cell.

Lytic cycle

A bacteriophage life cycle characterized by rapid replication within the host followed by host cell lysis/rupture.

Lysogenic cycle

A bacteriophage life cycle where the phage inserts its DNA into the host chromosome as a prophage, remaining dormant until triggered.

CRISPR

Clustered regularly interspaced short palindromic repeats that function as a bacterial 'immune system' by keeping copies of viral DNA for future recognition.

Toxoid vaccines

Vaccines that utilize an inactivated toxin made by a germ to create immunity to the pathogenic parts of the microbe rather than the microbe itself.

Saprotrophs

Organisms, primarily fungi, that act as principal decomposers by secreting enzymes to degrade and absorb dead organic matter.

Chitin

A unique and defining component of the fungal cell wall that provides structural integrity.

Ergosterol

A sterol unique to the fungal cell membrane, similar to cholesterol in animals, that maintains membrane fluidity.

Mycelium

A mass of branching, multinucleate cellular filaments (hyphae) that forms the body of a fungus.

Mutualism

A symbiotic relationship where both partner species benefit and may fail to grow independently if separated.

Commensalism

A symbiotic association where one partner benefits while the other is neither helped nor harmed.

Oligotrophic

An organism that is capable of living in environments that offer very low levels of nutrients, common among ocean microbes.

Gnotobiotic animals

Animals in which all associated microorganisms are known and defined, including 'germ-free' animals used for research.

Innate immunity

The body's first line of defense, providing immediate and non-specific protection against a wide range of invaders from birth.

NETosis

An unusual form of neutrophil cell death where the cell releases a web-like trap of DNA and antimicrobial proteins to catch and kill pathogens.

Opsonin

A substance, such as the complement protein $C3b$, that coats a bacterium to make it easier for phagocytes to ingest.

Interferon

A cytokine 'intruder alert' molecule secreted by virus-infected cells to help neighboring cells defend against the virus.

Defensins

Small antimicrobial peptides that can lyse most microbial cells and some enveloped viruses, forming a chemical barrier in the gut.