Lecture Notes: Eukaryotic and Prokaryotic Diversity – Vocabulary

Vocabulary flashcards covering key concepts from eukaryotic cell structure to prokaryotic diversity and the tuberculosis clinical focus.

Eukaryotic cell

A cell with a true nucleus and membrane-bound organelles; highly diverse in structure and function.

Microfilament

A cytoskeletal filament composed of actin that supports cell shape and movement.

Actin filament

A polymerized chain of actin monomers forming microfilaments involved in cell movement and structure.

Polymerization

Process of joining monomers to form polymers; in actin, it builds microfilaments.

Depolymerization

Disassembly of polymers into monomers; enables cytoskeletal remodeling.

Myosin

Motor protein that interacts with actin to generate force for movement.

Microtubule

A hollow filament of tubulin used for organelle movement and as tracks for motor proteins.

Tubulin dimer

The building block of microtubules (an alpha and a beta tubulin dimer).

9+2 array

Arrangement of microtubules in eukaryotic flagella/cilia: nine outer doublets and two central microtubules.

Flagellum

Long, whip-like organelle used for locomotion in many cells; in eukaryotes, built from microtubules in a 9+2 arrangement.

Cilium

Short, hair-like projection used for movement and feeding; numerous in some protozoa.

Trichomonas vaginalis

Flagellated protozoan parasite that causes vaginitis.

Paramecium

Ciliated, ovoid protozoan commonly used as a model eukaryotic cell.

What is the secret of prokaryotic survival?

They are extremely resilient and adaptable. They are metabolically flexible.

What is the name of the gram negative proteobacteria that can live in low nutrient environments e.g. ocean, glacial ice?

Alphaproteobacteria oligotrophs

Chlamydia elementary bodies

Metabolically inactive form that enters host cells.

Chlamydia reticulate bodies

Active, replicating form inside host cells.

Chlamydia life cycle

Lifecycle alternating between elementary bodies and reticulate bodies, with infection, replication, and exit.

Halophile

Organism that thrives in high-salt environments.

Halobacterium salinarum

Halophilic archaeon living in the Dead Sea.

Carbon fixation

Conversion of CO2 to organic carbon by autotrophs and some prokaryotes.

Nitrogen fixation

Reduction of atmospheric N2 to ammonia (NH3) by nitrogenase; makes nitrogen bioavailable.

Diazotroph

Microorganism capable of fixing atmospheric nitrogen.

Nitrogenase

Enzyme complex that catalyzes nitrogen fixation. Changing nitrogen to ammonia. Called Biological Nitrogen Fixation (BNF)

Rhizobium

Nitrogen-fixing genus that forms root nodules on legumes.

Root nodules

Plant structures housing bacteroids for nitrogen fixation.

What is the name of the gram negative proteobacteria that need a lot of organic nutrients?

Eutrophs- class betaproteobacteria

Where does betaproteobacteria grow?

Between aerobic and anaerobic areas e.g. mammalian intestines. There are some species that are human pathogens and can be life threatening.

What is the name of the gram negative proteobacteria that need a lot of organic nutrients?

Bacteroids

Bacterium-like cells within plant root nodules involved in nitrogen fixation.

Bergey’s Manual

Standard reference for bacterial taxonomy and systematics.

Prokaryote

Unicellular organism lacking a membrane-bound nucleus (bacteria and archaea).

Microbiome

Community of microorganisms living in a specific environment (e.g., the human body).

Symbiotic relationships

Close biological interactions between different species (mutualism, commensalism, parasitism).

Commensal/resident microbiota

Stable, resident microorganisms that typically do not harm the host.

Transient microbiota

Microorganisms that are present temporarily and do not establish long-term colonization.

Paracoccus denitrificans

Bacterium noted for survival outside native soil conditions under extreme gravity experiments.

10:1 bacteria to human cells

Approximate NIH estimate that bacteria outnumber human cells by about ten to one in the human body.

Rickettsia rickettsii

Causative agent of Rocky Mountain spotted fever; obligate intracellular parasite; requires special staining.

Alphaproteobacteria

Class of Proteobacteria known for oligotrophic (low-nutrient) lifestyles.

Pseudomonas aeruginosa

Gammaproteobacterium; aerobic, nonfermenting; causes infections and forms biofilms; often antibiotic resistant.

Why is Pseudomonas aeruginosa so difficult to treat?

It’s resistant to many antibiotics and can easily form biofilms.

Vibrio cholerae

Aquatic bacterium; produces cholera toxin leading to profuse watery diarrhea; thrives in alkaline environments. Causes hyper section of electrolytes and water in L intestines = watery diarrhea.

Escherichia coli

Common gut bacterium; model organism; diverse roles including pathogenesis in some strains.

Legionella pneumophila

Causative agent of Legionnaires disease; thrives in warm water systems and outbreaks via AC units.

Spirochetes

Phylum of bacteria with axial filaments and corkscrew-like motion.

Endoflagellum

Flagellum located between inner and outer membranes in spirochetes.

Bacteroides

Genus abundant in the human gut; usually mutualistic and helps prevent pathogen colonization.

Gardnerella vaginalis

Bacterium associated with bacterial vaginosis in women.

Mycobacterium

Genus with mycolic acids in the cell wall; acid-fast; includes M. tuberculosis and M. leprae.

M. tuberculosis

Causative agent of tuberculosis; acid-fast, high-G+C bacterium; grows slowly on culture.

M. leprae

Causative agent of Hansen’s disease (leprosy).

Corynebacterium diphtheriae

Causative agent of diphtheria; produces a pseudomembrane in the throat.

Diphtheria

Disease caused by C. diphtheriae; can be fatal if untreated.

Acid-fast staining

Staining method for Mycobacteria due to their mycolic acid-rich cell walls.

Mycolic acid

Long-chain fatty acids in Mycobacteria that contribute to acid-fastness and virulence.

Low G+C gram-positive

Group of Gram-positive bacteria with DNA G+C content below 50%.

Bacilli

Class of Gram-positive bacteria; morphologically diverse; includes Bacillus and Streptococcus among others.

Streptococcus pyogenes

Causative agent of strep throat and various skin infections.

Staphylococcus aureus

Gram-positive cocci in grape-like clusters; causes many infections; can produce enterotoxins and cause toxic shock; MRSA/VRSA strains are antibiotic resistant.

MRSA

Methicillin-resistant Staphylococcus aureus; difficult-to-treat, hospital-associated pathogen.

VRSA

Vancomycin-resistant Staphylococcus aureus; highly antibiotic resistant.

Clostridium difficile

Gram-positive rod causing severe colitis after antibiotic disruption of gut flora.

Lactobacillales

Order including Lactobacillus, Leuconostoc, Enterococcus, Streptococcus; low G+C Gram-positive bacteria.

Bacillus anthracis

Pathogen that causes anthrax in animals and humans.

Bacillus cereus

Bacillus species associated with food poisoning.

Lowenstein–Jensen agar

Specialized culture medium used to grow Mycobacterium tuberculosis.

Acid-fast bacteria (AFB)

Bacteria that retain carbol fuchsin stain due to high mycolic acid in their walls (e.g., Mycobacteria).