Microbial Genetics, Viruses, and Antimicrobial Control Review

Vocabulary flashcards covering microbial genetics, viral biology, microbial control methods, and principles of antimicrobial chemotherapy based on the Exam 2 Review Guide.

DNA Polymerases

Enzymes that synthesize a single strand of DNA in the $5'$ to $3'$ direction by base pairing to a single-strand template during DNA replication.

Origin

The specific start site on a chromosome where DNA replication is initiated.

Semiconservative Replication

The mode of DNA replication where each newly formed daughter chromosome contains one parental strand and one newly synthesized daughter strand.

Promoter

The start site sequence on a DNA gene where RNA polymerase binds to begin transcription.

Terminator

The stop site sequence on a DNA gene that signals RNA polymerase to halt transcription.

Operator

A regulatory DNA sequence within a gene that interacts with repressors or inducers to control transcription.

Repression

The regulatory mechanism that turns off gene transcription when a repressor protein interacts with the operator.

Induction

The regulatory mechanism that turns on gene transcription when an inducer molecule interacts with the operator.

Codon

A sequence of three nucleotides on messenger RNA that codes for a specific amino acid during translation.

Anticodon

A three-nucleotide sequence on transfer RNA that binds to a complementary mRNA codon to deliver an amino acid to the ribosome.

Genetic Code

The universal set of rules dictating which specific amino acid is delivered by a tRNA to the ribosome for a given mRNA codon.

Native State

The functional, properly folded three-dimensional structure of a protein determined by its amino acid sequence.

Spontaneous Mutation

A genetic alteration arising from errors made by DNA polymerases during DNA replication, resulting in sequence changes that can be neutral, harmful, or beneficial.

Transformation

The process of a bacterial cell acquiring free foreign DNA released by a dead donor cell.

Conjugation

The horizontal gene transfer process involving direct transfer of DNA from a living donor cell to a recipient cell.

Transposons

Small, linear segments of mobile DNA that carry genes and must reside within a plasmid or a chromosome.

Plasmids

Small, circular extrachromosomal DNA molecules that can transfer genes between bacterial cells.

Capsid

The protective outer protein coat of a virus that encloses its genetic material.

Spikes (Attachment Proteins)

Viral surface proteins that bind specifically to host cell receptors to mediate attachment.

Viral Envelope

A host-derived outer phospholipid bilayer present in some viruses that mediates host entry and exit.

Endocytosis

A cellular uptake mechanism utilized by all types of viruses to enter a host cell during penetration.

Membrane Fusion

A penetration mechanism exclusive to enveloped viruses where the viral envelope merges directly with the host cell membrane.

Lysis

A release mechanism used by naked and complex viruses that breaks the host cell membrane, immediately killing the host.

Budding

A release mechanism used by enveloped viruses where the viral nucleocapsid pushes through and acquires the host cell membrane, gradually killing the host cell.

Reverse Transcriptase

A viral matrix enzyme found in retroviruses that synthesizes a DNA copy from the viral RNA genome.

Provirus

A double-stranded DNA copy of a viral genome that is permanently integrated into the host cell's chromosome.

Latent Infection

A type of persistent viral infection characterized by sporadic symptoms, alternating between active viral replication and inactive phases.

Chronic Infection

A persistent infection where viral multiplication progresses slowly and symptoms gradually appear over an extended period.

Signs

Objective, observable indications of an infection or disease, such as a fever, cough, or rash.

Symptoms

Subjective characteristics of a disease experienced and reported solely by the patient, such as pain, headache, or fatigue.

Sterilization

The complete destruction or removal of all viable microbial life, including bacterial endospores.

Disinfection

The destruction or removal of vegetative pathogens on inanimate surfaces, but not necessarily endospores.

Antisepsis

The application of chemical agents to exposed body surfaces and living tissues to destroy or inhibit vegetative pathogens.

Biocidal Agent

An antimicrobial agent that kills microorganisms by damaging cell walls, cell membranes, proteins, or DNA.

Biostatic Agent

An agent that inhibits the growth and metabolic multiplication of microbes without directly killing them.

Prophylaxis

The administration of an antimicrobial drug to prevent an anticipated infection in a healthy individual.

Selective Toxicity

The ability of an antimicrobial drug to injure or destroy target microbes without causing harm to host cells.

Therapeutic Index

A numerical ratio comparing the toxic dose of a drug to its effective therapeutic dose, assessing selective toxicity.

Superinfection

A secondary infection that develops when broad-spectrum antimicrobial therapy eliminates protective resident microbiota, enabling resistant microbes to overgrow.

Drug Synergism

An enhanced antimicrobial effect achieved by combining two or more drugs that is significantly greater than the additive effect of either drug alone.

Selective Pressure

Environmental influences—such as the clinical overuse and misuse of antibiotics—that kill susceptible microbes and drive the proliferation of drug-resistant strains.