BIOL120 Microbiology - Chapter 1: The Microbial World

Vocabulary flashcards covering Chapter 1 concepts from the Microbiology lecture notes.

Microorganisms (microbes)

Life forms so small they cannot be seen with the naked eye; most are single-celled; some multicellular; inhabit every environment; live in microbial communities.

Prokaryote

Organisms whose cells lack a true nucleus and membrane-bound organelles (Bacteria and Archaea).

Eukaryote

Organisms whose cells have a true nucleus and membrane-bound organelles (plants, animals, fungi, and protists).

Cytoplasmic membrane (cell membrane)

Phospholipid bilayer that encloses the cytoplasm and regulates what enters and leaves the cell.

Cytoplasm

Aqueous interior of the cell containing macromolecules, ions, metabolites, and ribosomes; site of many metabolic processes.

Ribosomes

RNA–protein complexes that synthesize proteins in cells.

Cell wall

Rigid layer that provides structural strength; present in many microbes (e.g., bacteria, fungi) but not in all organisms.

Genome

A cell’s complete set of genes (its hereditary material).

Nucleoid

Region in prokaryotic cells where the chromosome resides; not bounded by a membrane.

Enrichment culture

Growth conditions designed to favor the growth of specific microbes from a mixed sample.

Pure culture

A culture containing only a single microbial species/strain.

Colony

Visible population arising from a single cell grown on a solid medium.

Aseptic technique

Procedures used to prevent contamination of cultures and their environment.

Medium

Nutrient liquid or solid used to grow microbes.

Pasteurization

Controlled heating to kill pathogens and reduce microbial load in foods and liquids.

Swan-necked flask experiment

Pasteur’s experiment showing that boiled broth remains sterile unless dust enters; disproved spontaneous generation.

Spontaneous generation

Hypothesis that life can arise from nonliving matter; disproved by Pasteur.

Koch’s postulates

Criteria linking a microbe to disease: (1) present in diseased hosts and absent in healthy ones; (2) grown in pure culture; (3) causes disease when introduced into a healthy host; (4) reisolated and identical to the original microbe.

Agar

Gelatinous substance used to solidify growth media for microbial cultures, enabling isolation of colonies.

Tree of Life / Three domains

Classification system based on rRNA showing three domains—Bacteria, Archaea, Eukarya—with Archaea distinct from Bacteria and Eukarya.

LUCA (Last Universal Common Ancestor)

The most ancient cell from which all current life descended.

Genomics

Study of the complete genome sequences of organisms.

Transcriptomics

Study of the complete set of RNA transcripts produced by a cell or organism.

Proteomics

Study of the full set of proteins produced by a cell or organism.

Metabolomics

Study of the complete set of metabolites produced during metabolism.

Fermentation

Metabolic process producing energy without oxygen, yielding products like lactic acid or ethanol; widely used in foods and industry.

Mycorrhiza

Symbiotic association between fungi and plant roots that enhances nutrient uptake.

Nitrogen-fixing bacteria

Microbes that convert atmospheric N2 to ammonia (NH3), vital for the nitrogen cycle (e.g., in root nodules of legumes).

Bioremediation

Use of microorganisms to detoxify or remove pollutants from the environment.

Industrial microbiology

Application of microbes to industry, including fermentation, biotechnology, biofuels, and wastewater treatment.

Pathogens

Microorganisms that cause disease in plants, animals, or humans.

Global distribution/biomass of microbes

Total microbial cells ≈ 2.5 × 10^30; most are in oceans and subsurface; microbial biomass contains about 5 × 10^17 g of carbon.

Five-kingdom classification

Whitaker’s traditional model dividing life into Monera, Protista, Fungi, Plantae, Animalia; later replaced by the three-domain system based on rRNA.

Rumen microorganisms

Microbes living in the rumen of ruminant animals that aid digestion of plant material.

Germ Theory

Idea that infectious diseases are caused by microorganisms; established through work like Koch’s, leading to disease prevention and vaccines.