Chapter 4: Functional Anatomy of Prokaryotic and Eukaryotic Cells

Functional Anatomy of Prokaryotic and Eukaryotic Cells begins by outlining the basic characteristics of prokaryotes (bacteria and archaea) and eukaryotes (protozoa, fungi, algae, plants, and animals), emphasizing key differences in complexity, size, and organelle presence. The chapter explores the three basic shapes of bacteria—coccus, bacillus, and spiral—and their various arrangements such as streptococci and staphylococci. It details bacterial cell structures, including the glycocalyx (capsules and slime layers), which aids in adhesion and evasion of the immune system. Flagella, axial filaments, fimbriae, and pili are introduced as motility and attachment structures, with flagellar arrangement and function described in depth. The bacterial cell wall is emphasized as a crucial feature distinguishing Gram-positive from Gram-negative bacteria, with peptidoglycan as the primary structural component. The Gram stain technique and acid-fast staining are revisited to illustrate cell wall differences and their clinical implications. Plasma membranes are discussed in terms of selective permeability and the role of passive and active transport mechanisms, including group translocation. Cytoplasmic components such as ribosomes (70S in prokaryotes vs. 80S in eukaryotes), inclusions, and endospores are explained in relation to storage, survival, and protein synthesis. Eukaryotic cells are described with a focus on membrane-bound organelles: the nucleus, endoplasmic reticulum, Golgi complex, mitochondria, chloroplasts, lysosomes, and peroxisomes, along with the cytoskeleton and processes like phagocytosis. The chapter closes with a synthesis of the structural and functional differences between prokaryotes and eukaryotes and how these differences influence microbial classification, physiology, and response to treatment. This foundational knowledge prepares students to understand cellular targets of antibiotics, microbial evolution, and pathogenesis.