JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD Pharm. D II Year PHARMACEUTICAL MICROBIOLOGY Previous Question Paper (November/December - 2021 - R08)

Fungi are eukaryotic, heterotrophic organisms that exist in two primary morphological forms: unicellular yeasts and multicellular filamentous molds. The basic structural unit of filamentous fungi is the hypha, a tubular, branching filament. A mass of intertwined hyphae is collectively termed the mycelium.

Hyphae are categorized based on their structure:

• Septate hyphae: Divided into distinct cells by cross-walls called septa, which contain pores allowing for the movement of cytoplasm and organelles.
• Coenocytic (aseptate) hyphae: Continuous, multinucleated tubes lacking cross-walls.

The mycelium is further differentiated into vegetative mycelium, which penetrates the substrate to absorb nutrients, and aerial (reproductive) mycelium, which projects above the surface and bears reproductive structures like conidia or sporangiospores. Yeasts, by contrast, are non-filamentous, unicellular fungi that typically reproduce by budding or fission. Some fungi are dimorphic, existing as molds at room temperature and as yeasts at body temperature (37°C).

Diagram description: The diagram should illustrate a mycelial network consisting of branched, septate hyphae with visible nuclei and septal pores. A section of the aerial mycelium should show a conidiophore bearing chains of conidiospores, while a separate section depicts a budding yeast cell with a visible bud scar.

The microbial world is primarily divided into three domains based on ribosomal RNA sequence analysis: Bacteria, Archaea, and Eukarya.

• Bacteria and Archaea: Both are prokaryotic, lacking a membrane-bound nucleus and organelles. Bacteria possess peptidoglycan in their cell walls, whereas Archaea lack peptidoglycan and often inhabit extreme environments.
• Eukarya: Includes fungi, protozoa, and algae. These organisms possess a true nucleus and membrane-bound organelles.

The relationship among these domains is represented by a phylogenetic tree, where Bacteria and Archaea are evolutionarily distinct from each other, but Archaea share a more recent common ancestor with Eukarya than with Bacteria. Viruses are considered acellular entities that exist outside this three-domain system, as they require host cellular machinery for replication.