Microbiology Exam 1 Study Guide: Foundations, Cell Structure, and Disease Survey

Chapter 1: Introduction to Microbiology

Microorganisms and Their Importance

Microbiology is the study of microorganisms (also called microbes), which are organisms too small to be seen with the naked eye. These include bacteria, archaea, fungi, protozoa, algae, and viruses.

• Microorganisms: Living organisms such as bacteria, archaea, fungi, protozoa, and microscopic algae; viruses are considered non-living but are studied in microbiology.

• Pathogens: Microbes that cause disease. True pathogens cause disease in healthy hosts, while opportunistic pathogens cause disease mainly in immunocompromised individuals.

• Abiogenesis vs. Biogenesis: Abiogenesis is the idea that life can arise from non-living matter; biogenesis states that life arises only from pre-existing life.

• Louis Pasteur: Disproved spontaneous generation through experiments showing that microbes come from other microbes, not from non-living material.

• Koch's Postulates: Criteria to establish a causative relationship between a microbe and a disease. Useful for identifying pathogens but have limitations (e.g., not all microbes can be cultured).

Key Concepts in Microbiology

• Etiological Agent: The specific microorganism that causes a disease.

• Pasteurization: The process of heating liquids to kill most bacteria and prevent spoilage.

• Aseptic Technique: Methods to prevent contamination by unwanted microorganisms during laboratory procedures.

• Sterile: Free from all living microorganisms.

• Healthcare-Associated Infections (HAIs): Infections acquired in healthcare settings, often due to lapses in aseptic technique.

• Scientific Method: A systematic approach involving observation, hypothesis formation, experimentation, and analysis.

• Taxonomy: The science of classifying organisms. The taxonomic hierarchy is: Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species.

• Domain vs. Kingdom: Domain is the highest taxonomic rank (Bacteria, Archaea, Eukarya); Kingdom is a lower rank within domains.

• Symbiotic Relationships: Interactions between different species, including commensalism, parasitism, and mutualism.

Chapter 3: Prokaryotic Cell Structure and Function

Prokaryotic Cells: Overview

Prokaryotes include Bacteria and Archaea. They lack a membrane-bound nucleus and organelles.

• Prokaryotic vs. Eukaryotic Cells: Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have both.

• Species: A group of organisms capable of interbreeding and producing fertile offspring. In prokaryotes, species are defined by genetic similarity.

• Domains: Bacteria and Archaea are prokaryotic domains; Eukarya is the eukaryotic domain.

• Cell Morphology: Shapes include bacilli (rods), cocci (spheres), spirilla (spirals), and others. Arrangements include single, diplo-, strepto-, staphylo-.

• Binary Fission: The process by which prokaryotes reproduce asexually by dividing into two identical cells.

Cell Wall and Membrane Structures

• Peptidoglycan: A polymer forming the cell wall of most bacteria, providing structural support.

• Gram-Positive vs. Gram-Negative: Gram-positive bacteria have thick peptidoglycan layers; Gram-negative have thin layers and an outer membrane containing lipopolysaccharides (LPS).

• Acid-Fast Bacteria: Have waxy cell walls with mycolic acids; acid-fast stain is used for identification (e.g., Mycobacterium).

• Plasma Membrane: Controls transport into and out of the cell; composed of a phospholipid bilayer.

• Transport Mechanisms: Include passive (diffusion, facilitated diffusion) and active (requires energy) transport.

• Osmosis: Movement of water across a semipermeable membrane; cells can be affected by hypotonic, hypertonic, or isotonic solutions.

External Structures

• Flagella: Used for motility; arrangement and structure differ between prokaryotes and eukaryotes.

• Fimbriae and Pili: Hair-like structures for attachment and genetic exchange.

• Glycocalyx: A protective layer outside the cell wall; can be a capsule (organized) or slime layer (loose).

• Cytoplasm: Gel-like substance inside the cell containing ribosomes, nucleoid, and inclusions.

• Nucleoid: Region containing the bacterial chromosome (DNA).

• Cytoskeleton: Protein filaments providing structural support.

• Ribosomes: Sites of protein synthesis; prokaryotic ribosomes are 70S.

• Inclusion Bodies: Storage sites for nutrients and other substances.

• Endospores: Highly resistant structures formed by some bacteria for survival in harsh conditions.

Chapter 4: Introduction to Eukaryotic Cells

Eukaryotic Cell Structure and Function

Eukaryotic cells have a true nucleus and membrane-bound organelles. They include animals, plants, fungi, and protists.

• Endosymbiotic Theory: Proposes that mitochondria and chloroplasts originated from free-living bacteria engulfed by ancestral eukaryotic cells.

• Cell Division: Eukaryotes divide by mitosis (asexual) and meiosis (sexual reproduction).

• Transport Mechanisms: Include endocytosis (phagocytosis, pinocytosis, receptor-mediated) and exocytosis.

• Kingdoms: Four main eukaryotic kingdoms: Protista, Fungi, Plantae, Animalia.

• Helminths: Parasitic worms; two main groups are flatworms and roundworms.

• Fungi: Can reproduce sexually or asexually; produce spores; hyphae are filamentous structures.

• Protists: Diverse group; sometimes called a "catchall" kingdom.

• Pseudopods: Extensions of cytoplasm used for movement by some protists.

• Plasma Membrane: Contains phospholipids and sterols; structural and functional features differ from prokaryotes.

• Glycocalyx: Present in some eukaryotes; involved in cell recognition and protection.

• Flagella and Cilia: Used for movement; eukaryotic flagella are structurally different from prokaryotic flagella.

• Ribosomes: Eukaryotic ribosomes are 80S; located in the cytoplasm and on the rough endoplasmic reticulum.

• Cytoskeleton: Includes microtubules, centrioles, and intermediate filaments; provides structural support and aids in movement.

• Nucleus: Contains genetic material; surrounded by a nuclear envelope.

• Endoplasmic Reticulum (ER): Rough ER (with ribosomes) synthesizes proteins; smooth ER synthesizes lipids.

• Chloroplasts: Organelles for photosynthesis in plants and algae.

• Mitochondria: Sites of cellular respiration; share similarities with bacteria (e.g., own DNA, double membrane).

Disease Survey

Major Microbial Diseases

For each disease, know the causative agent, type of microbe, signs/symptoms, and transmission route.

Disease	Causative Agent	Type of Microbe	Transmission Route
Cholera	Vibrio cholerae	Bacterium	Fecal-oral (contaminated water/food)
Bubonic Plague	Yersinia pestis	Bacterium	Flea bites, respiratory droplets
Anthrax	Bacillus anthracis	Bacterium	Contact, inhalation, ingestion
Tuberculosis	Mycobacterium tuberculosis	Bacterium	Airborne (respiratory droplets)
Syphilis	Treponema pallidum	Bacterium	Sexual contact, congenital
Ringworm/Athlete's foot (Tinea)	Dermatophyte fungi	Fungus	Direct contact, fomites
Yeast infection	Candida species	Fungus	Opportunistic, endogenous
Giardia	Giardia lamblia	Protozoan	Fecal-oral (contaminated water)
Trichomonas	Trichomonas vaginalis	Protozoan	Sexual contact
Malaria	Plasmodium species	Protozoan	Vector-borne (mosquito)

Additional info:

• Some details, such as the full taxonomic hierarchy and specific examples of symbiotic relationships, were expanded for academic completeness.

• For the disease survey, causative agents and transmission routes were inferred based on standard microbiology knowledge.