Microbiology Final Exam Study Guide Notes

Microbiology Final Exam Study Guide Notes

Antibiotic Resistance Mechanisms

  • Antibodies vs. Antibiotics
    • Antibodies are produced by multicellular organisms and not by bacteria.
    • Bacteria utilize molecular strategies to resist antibiotics, not antibody production.

Mutation and Their Effects

  • Mutations
    • Many mutations are neutral, silent, or beneficial; thus, only some are harmful.
    • Certain mutations can enhance cellular functions under specific conditions.

Disinfectants vs Antiseptics

  • Chemical Agents
    • Disinfectants: Stronger substances used on surfaces.
    • Antiseptics: Milder agents deemed safe for skin/mucous membranes.

Antibiotics

  • Sources of Antibiotics
    • Naturally produced by bacteria (e.g., Streptomyces produces streptomycin).
    • Naturally produced by fungi (e.g., Penicillium produces penicillin).
    • Synthetically created in labs (e.g., fluoroquinolones).

Selectively Toxic Antivirals

  • Targeting Viral Components
    • Antivirals must focus on viral components/processes without harming the host.

Antifungal Drug Targets

  • Challenges in Targeting Fungi
    • Targeting DNA replication is not effective for fungi due to conservation with human DNA.
    • Better approaches include targeting fungal-specific pathways like ergosterol synthesis.

Antibiotics and Prokaryotes

  • Specific Mechanisms Targeted
    • Antibiotics target processes specific to prokaryotes such as cell wall synthesis, protein synthesis, and DNA replication.
    • Note: Viruses are not prokaryotes and lack a cell wall and independent metabolism.

Resistance Mechanism of Biofilms

  • Biofilm Protection
    • Biofilms shield bacteria from antibiotics and immune responses, making them less susceptible.

Innate Immunity

  • General Mechanisms
    • Utilizes broad, nonspecific defenses such as skin, mucous membranes, phagocytes, NK cells, and inflammatory responses.

Phagocytosis Steps

  • Sequential Process
    1. Move towards and attach to particle
    2. Ingestion
    3. Form phagolysosome
    4. Digestion
    5. Exocytosis (release waste)

Tryptophan Regulation

  • Operon Mechanism
    • When tryptophan levels are high:
    • Activates TrpI (the repressor).
    • Repressor binds to the operator, blocking RNA polymerase, thereby turning the operon off.

Bacteriostatic vs Bactericidal

  • Efficacy of Antibiotics
    • Bacteriostatic: Inhibits bacterial growth and reproduction without killing bacteria.
    • Sterilization: Destroys all microbes, including spores, viruses, and fungi.

Gene Expression Process

  • Two Key Steps
    • Transcription: Converts DNA to mRNA.
    • Translation: Converts mRNA to protein.

Horizontal Gene Transfer Mechanisms

  • Types of Gene Transfer
    • Conjugation: Direct transfer of DNA via pilus.
    • Transduction: Transfer of bacterial DNA via bacteriophage (virus).

Mechanical Barriers in Immunity

  • Physical Defense Mechanisms
    • Liquid flow (e.g., urination) serves as a barrier against microbes by flushing pathogens from the urinary tract.

Role of Soaps and Detergents

  • Mechanism of Action
    • Disrupt cell membranes and emulsify oils/dirt.
    • Scrubbing and rinsing ensure physical removal of microbes.

Promoter Functionality

  • Gene Expression Control
    • Promoters are DNA sequences where RNA polymerase binds to initiate transcription, thus regulating gene expression.

Antimicrobials Target Bacteria

  • Reasons for Targeting Bacteria
    • Bacteria have distinct cellular processes that can be targeted, differing from human cells.
    • Rapid growth rates make testing for susceptibility straightforward.