Microbiology Level 1 Quiz

Study Notes

Microbiology is the study of microorganisms too small to be seen with the naked eye, including bacteria, fungi, algae, and viruses.
Microorganisms are categorized into fields of study, such as bacteriology, virology, mycology, protozoology, and parasitology.
A microorganism is a very small organism that cannot be seen with the naked eye.

Bacteria are prokaryotic organisms—one-celled organisms without a true nucleus.
Bacterial naming follows nomenclature rules: genus (capitalized) and species (lowercase). Both are italicized.
Examples include Staphylococcus aureus, Bacillus anthracis, and Escherichia coli.
Bacterial cells have several key components: capsule, cell wall, cell membrane, cytoplasm, ribosomes, chromosomal DNA (in the nucleoid), and flagella (not present in all).

Capsule: Composed of polysaccharides, protecting bacteria from immune system attack and antibiotics.
Cell Wall: A rigid, porous layer composed of peptidoglycan, providing shape and protection from mechanical damage/lysis. Peptidoglycan is composed of alternating subunits: N-acetylmuramic acid (NAM) and N-acetylglucosamine (NAG).
Cell Membrane: A lipid bilayer that encloses the cytoplasm, controlling the passage of substances like ions, proteins, and nutrients.
Cytoplasm: The fluid inside the cell, containing various organelles, and composed of water and salts.
Ribosomes: Sites of protein synthesis.
DNA: (Chromosome) Contains the bacterial cell's genetic information, located in the nucleoid region.
Plasmids: Circular, supercoiled, double-stranded DNA molecules that carry extra genes, such as antibiotic resistance traits.
Flagella: Structures for bacterial movement, not always present.
Pilus: Structures that facilitate attachment to surfaces and transfer of genetic material between cells, not always present.

Shapes: Cocci (spherical), bacilli (rod-shaped), coccobacilli (elongated bacilli), vibrio (comma-shaped), spirillum (spiral).
Arrangements: Depends on how cells divide and separate: diplococci (pairs), streptococci (chains), staphylococci (clusters), tetrads (groups of four), sarcina (cuboidal packets) in cocci; scattered, diplobacilli (pairs), streptobacilli (chains) in bacilli.

Gram staining differentiates bacteria based on cell wall structure.
Gram-positive bacteria have a thick peptidoglycan layer, staining violet. Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane, staining red-purple.

Classified by cell wall composition (Gram-positive or Gram-negative).
Based on their pathogenicity, including pathogenic and non-pathogenic species (ability to cause disease).
Based on spore-forming ability (endospore-forming or not).

Nutritional Requirements: Bacteria need macronutrients, micronutrients (trace elements), and growth factors.
Environmental Requirements: Bacteria have different optimal temperature ranges—psychrophiles, mesophiles, thermophiles, and extreme thermophiles. Optimal pH, atmospheric oxygen, osmotic pressure.

Binary Fission: The primary method of bacterial reproduction.
Growth Curve phases: Lag phase, log phase, stationary phase, and death phase.

Culture Media: Nutrient materials that support microbial growth, classified as complex or synthetic (chemically defined).
Types of Media: Complex, enriched, selective, differential media