Exam 2 Study Guide Flashcards: Chapters 6 to 10

Comprehensive vocabulary flashcards covering microbial nutrition, growth, metabolism, genetics, physical and chemical microbial control, and antimicrobial drugs from Chapters 6 through 10.

Macronutrients

Nutrients required by an organism in relatively large quantities that play principal roles in cell structure and metabolism.

Micronutrients

Nutrients required in smaller amounts that are involved in enzyme function and the maintenance of protein structure (also known as trace elements).

Saprobe

A free-living microbe that feeds primarily on organic detritus from dead organisms.

Parasite

An organism that lives on or within another organism (the host), obtaining nutrients while causing some degree of harm to the host.

Osmosis

The diffusion of water across a selectively permeable membrane.

Isotonic

An environmental condition in which the external solute concentration equals that of the cell interior, resulting in no net water movement.

Hypotonic

An environmental condition where the solute concentration outside the cell is lower than inside, causing water to diffuse into the cell.

Hypertonic

An environmental condition where the solute concentration outside the cell is higher than inside, causing water to exit the cell and shrink the protoplast.

Doubling Time

The period of time required for a complete fission cycle from one parent cell to two daughter cells, driving exponential growth.

Biofilm

A structured community of microorganisms adhering to a surface and to each other, displaying characteristics distinct from free-floating planktonic bacteria.

Metabolism

The totality of all chemical reactions and physical workings that occur inside a living cell.

Catabolism

The phase of metabolism that breaks down complex organic compounds into simpler molecules, releasing energy.

Anabolism

The phase of metabolism that synthesizes complex cellular molecules from simpler components, requiring an input of energy.

Constitutive Enzymes

Enzymes that are always present in relatively constant amounts in the cell, regardless of substrate concentration.

Regulated Enzymes

Enzymes whose production is turned on (induced) or turned off (repressed) in response to variations in substrate concentration.

Redox Reaction

A coupled chemical reaction in which electrons are transferred, with one compound losing electrons (oxidation) and another compound gaining them (reduction).

Glycolysis

A catabolic pathway that breaks down glucose into pyruvic acid, serving as the common initial step for aerobic respiration, anaerobic respiration, and fermentation.

Fermentation

The incomplete oxidation of glucose or other carbohydrates without oxygen, using an organic compound as the final electron acceptor.

Genome

The complete sum of genetic material carried within a cell or organism.

Gene

A distinct chromosomal segment or sequence of nucleotides in DNA that codes for a specific functional product, such as a protein or RNA molecule.

Genotype

The precise genetic makeup of an organism, representing its total collection of genes.

Phenotype

The observable physical and physiological traits expressed by an organism as a result of its genotype.

Semiconservative Replication

A mode of DNA replication wherein each newly formed double helix contains one preserved parental strand and one newly synthesized daughter strand.

Transformation

A mode of horizontal gene transfer in bacteria where a competent recipient cell acquires free, naked soluble DNA from the surrounding environment.

Transfection

The process of introducing naked or foreign genetic material deliberately into eukaryotic cells.

Transduction

The transfer of bacterial DNA from a donor cell to a recipient cell mediated by a bacteriophage vector.

Silent Mutation

A base-pair alteration in DNA that alters a codon but does not change the amino acid inserted into the polypeptide chain.

Missense Mutation

A base substitution that results in a codon specifying a different amino acid than the original sequence.

Nonsense Mutation

A base-pair substitution that alters a normal amino acid codon into a premature stop codon, terminating protein synthesis early.

Frameshift Mutation

A mutation resulting from the insertion or deletion of bases not in multiples of three, shifting the reading frame of the mRNA message.

Sterilization

A physical or chemical process that completely destroys or eliminates all viable forms of microbial life, including bacterial endospores and viruses.

Disinfection

The destruction or removal of vegetative pathogenic microorganisms on inanimate surfaces, which typically spares bacterial endospores.

Antisepsis

The application of chemical agents to exposed body surfaces, wounds, and surgical incisions to destroy or inhibit vegetative pathogens.

Sanitization

A mechanical cleansing process that removes debris and reduces microbial counts on inanimate objects to levels considered safe by public health standards.

Degermation

The mechanical reduction of the microbial population on living tissue, typically through scrubbing or the application of alcohol swabs.

Thermal Death Time (TDT)

The minimum length of time required to kill all test microorganisms at a specified temperature.

Thermal Death Point (TDP)

The lowest temperature required to kill all microorganisms in a liquid suspension within 10 minutes.

Lyophilization

A preservation technique involving rapid freezing and simultaneous desiccation under vacuum to preserve viable microbes in a dried state.

Therapeutic Index

The ratio comparing the toxic dose of a drug to its minimum effective therapeutic dose, where a higher ratio reflects greater drug safety.

Selective Toxicity

The property of an antimicrobial agent to kill or inhibit microbial pathogens without causing significant injury to host cells.

Superinfection

A secondary infection that develops when antimicrobial treatment eradicates the host's normal microbiota, allowing opportunistic or drug-resistant pathogens to proliferate.