In class notes Microbio 10/21/25

Planktonic algae, including dinoflagellates, produce most of the molecular oxygen in Earth's atmosphere.
- Importance: Fundamental for maintaining oxygen levels and supporting life on Earth.
- Utilization: Upon death, they transform into petroleum or fossil fuels.
- Implication: Their growth can be exploited for energy resources.

Protozoa are a group of organisms characterized by:
- Eukaryotic: Contain a nucleus and organelles.
- Unicellular: Comprised of a single cell.
- Heterotrophic: They do not produce their own food; instead, they obtain nutrients through feeding.

Found in various environments, notably:
- Water: Commonly observed in lake water (microscopic observation).
- Soil: Many species also inhabit soils.
- Animal microbiota: They exist within the microbiomes of numerous animals.

Cellularity: Unicellular organisms.
Eukaryotic nature: Distinguished from prokaryotes (bacteria).
Nutritional strategy: Heterotrophic, must consume other organisms for energy.
Reproductive strategies:
- Asexual reproduction:
- Fission: One cell grows and divides into two (binary fission similar to bacteria).
- Budding: Involves unequal division where a smaller cell (bud) detaches from the parent cell.
- Schizogony: Multiple nuclei form within one cell before subdividing into individual cells resembling multiple personalities/brains.
- Sexual reproduction: Involves conjugation, where:
- Two nuclei (macronucleus and micronucleus) exchange micronuclei.
- This leads to genetic variability and creation of genetically distinct offspring.
- Result: Two haploid nuclei merge to form a zygote.

Some protozoa can form cysts, allowing them to survive adverse conditions for extended periods.
- Example: Giardia, a pathogen responsible for cruise ship diarrheal infections, can withstand sanitation efforts due to its cyst form.
- Implication: Cysts require special consideration in sanitation to prevent transmission.

Pellicle: A hard outer covering that provides protection and structure.
Cytosol: Refers to the cell's cytoplasm, involved in metabolic processes.
Anal pore: Facilitates waste expulsion post-digestion.
Vacuoles: Specialized structures for digestion, playing a significant role in nutrient absorption and waste removal.

Helminths commonly known as worms:
- They are multicellular organisms and can be easily observed with the naked eye.
- Example: Seen in dogs and cats (like spaghetti appearance in feces).

Phyla:
- Platyhelminthes: Flatworms, remembered as "flat" (like platypus).
- Nematoda: Roundworms, distinguished by being round.

Cellular makeup: They are animals, sharing similarities with human cells, complicating treatment options due to potential side effects on humans.
Most helminths are parasitic, needing hosts to complete their life cycles.
- Lifespan includes specific larval stages occurring within particular hosts.

Historical misconception: Eating tapeworms was once considered a weight-loss strategy, as they would absorb nutrients from food consumed by the host.
Awareness: Highlighted as an ineffective and dangerous method of weight control.

Monoecious helminths: Can function as both male and female based on reproductive needs (hermaphroditic characteristics).
Dioecious helminths: Have distinct male and female individuals, requiring both for reproduction.
- Example: If male worms are present in abundance, some can change to female for reproductive needs.

Understanding these diverse groups is crucial for microbiology and ecology, reflecting their roles in ecosystems, human health, and environmental interactions. The knowledge underscores the importance of careful handling and treatment of contaminated water and food sources to prevent parasitic infections from protozoa and helminths.