Microbiology Week 1

What is the difference between microorganisms, pathogens, and disease-causing agents?

• Microorganisms: tiny living organisms (bacteria, fungi, protozoa, viruses).

• Pathogens: microorganisms that cause disease.

• Disease-causing agents: can include biological (bacteria, viruses), chemical, or physical factors.

What are the attributes of living organisms?

Growth, reproduction, metabolism, response to environment, homeostasis, and cellular organization

What’s the difference between eukaryotes and prokaryotes?

Eukaryotes have a nucleus and membrane-bound organelles; prokaryotes lack both

What is taxonomy?

The scientific system for classifying and naming organisms based on shared traits.

What is the binomial naming system for microbes?

Each species has a two-part Latin name: Genus (capitalized) and species (lowercase), both italicized.

What’s the purpose of classifying microbes?

To identify relationships between organisms and predict characteristics or disease potential.

What’s the difference between resident flora and opportunistic infection?

Resident flora are normal microbes living in or on the body; opportunistic infections occur when those microbes cause disease under weakened conditions.

The shape and arrangement of bacterial cells.

cocci (spherical), bacilli (rod-shaped), and spiral (corkscrew)

What are common bacterial shapes?

Cocci (spherical), bacilli (rod-shaped), spirilla/spirochete (spiral), vibrio (comma-shaped).

What do cocci arrangements include?

Single rods, diplobacilli (pairs), streptobacilli (chains)

How can morphology help identify bacteria?

Shape and arrangement help narrow down bacterial types and possible diseases

Give an example of morphology and related disease.

Streptococcus pyogenes (streptococci) → strep throat.

Protects bacteria from drying out and from immune system attacks.

A bacterial capsule,

What’s the role of the cell wall?

Maintains shape and prevents cell rupture; differs between Gram + and Gram – bacteria.

What does a cell membrane do?

Controls transport of materials in and out of the cell.

What is DNA loop or nucleoid region?

Contains the bacterial genetic material (no true nucleus).

What is the function of plasmids?

Small circular DNA molecules carrying extra genes, often for antibiotic resistance

What’s the role of ribosomes?

Site of protein synthesis.

What are endospores?

Dormant, tough structures that allow bacteria to survive harsh conditions.

What is the function of flagella?

Provides motility (movement)

What do pili or fimbriae do?

Help bacteria attach to surfaces or other cells.

What enzyme helps in DNA replication

Gyrase enzyme — prevents DNA from supercoiling during replication.

What’s the difference between Gram-positive and Gram-negative cell walls?

Gram+ have thick peptidoglycan and stain purple; Gram– have thin peptidoglycan and an outer membrane, staining pink/red.

Why is the Gram stain important?

Helps identify bacterial type, structure, and antibiotic susceptibility.