Microbiology Lecture: Chapter 5 - Microscopic Eukaryotes

Introduction

• Focus on microscopic eukaryotes.
• Complex and diverse group.
• Importance of understanding similarities, differences, beneficial aspects, and disease-causing potential.

Protozoa

Characteristics

• Eukaryotic and unicellular.
• Can be free-living or parasitic.
• Possess complex membrane-bound organelles.

Life Cycle

• Trophozoite Stage: Active feeding, metabolic activities.
• Cyst Formation: Allows survival in harsh conditions.

Reproduction

• Binary fission (similar to mitosis).
• Schizogony (multiple nuclear replications, cell bursts into many cells).

Structure

• Plasma membrane (plasma lemma).
• Pelicle: Extra protective protein coating.
• Ectoplasm: Jelly-like, movement structures.
• Endoplasm: Fluid-like, contains organelles.
• Movement structures: Flagella, cilia, pseudopods.

Disease-Causing Protozoa

Amoebozoa

• Entamoeba histolytica: Causes illness through contaminated food/water. Life cycle involves cyst ingestion, trophozoite activity in intestines, potential bloodstream spread.
• Naegleria fowleri: Brain-eating amoeba, infects via contaminated water entering nasal passage.

Apicomplexa

• Plasmodium: Causes malaria, transmitted via mosquito bites, infects liver and red blood cells.
• Toxoplasma gondii: Causes toxoplasmosis, common in cats, dangerous for pregnant women and young children.

Flagellates

• Trypanosoma: Causes African sleeping sickness and Chagas disease, transmitted by tsetse fly or kissing bug.

Parasitic Helminths

Nematodes (Roundworms)

• Ascaris lumbricoides: Large worms, infect through contaminated food.
• Enterobius vermicularis: Pinworms, common in children, eggs laid around anus.

Platyhelminths (Flatworms)

• Trematodes (Flukes): Feed on tissues, example: schistosoma.
• Cestodes (Tapeworms): Live in intestines, absorb food across the surface. Can migrate to other organs like the brain.

Fungi

Characteristics

• Saprobes: Consume decaying matter.
• Can be opportunistic pathogens.

Types

• Molds: Grow through hyphae.
• Yeasts: Unicellular, e.g., Candida albicans.

Dimorphic Fungi

• Histoplasma capsulatum: Grows in bat/bird feces-exposed soil, can cause chronic lung infections.

Algae

Types

• Brown Algae: Kelp, non-microscopic.
• Red Algae: Source of agar used in microbiology media.
• Green Algae: Photosynthetic, produce oxygen.

Microscopic Algae

• Diatoms: Produce oil.
• Dinoflagellates: Cause red tide, dangerous for marine life.

Study Recommendations

• Organize groups into outlines to aid in memorization and understanding.

Note: The lecture includes several video references to illustrate diseases and processes but watching them is optional.