5-Bacterial Ultrastructure - Cell Wall, Structure and Biosynthesis of Bacterial Cell Wall.
Covers the bacterial cell membrane, its composition and four functions, then peptidoglycan: its sugar-based structure, the four-step biosynthesis from cytoplasmic precursors to transpeptidase cross-linking, and its roles in rigidity, shape, protection and immune activation. It then contrasts Gram-positive walls, with teichoic and lipoteichoic acids, against Gram-negative walls, with the outer membrane, lipopolysaccharide and porins, and closes with surface antigens, adhesins and capsules.
Topic 5 of 113 in the MU Sofia syllabus for Microbiology (Dental Medicine, Year 2). The free AceMed note covers it in 3 sections, about 966 words (7 min of reading), with 14 flashcards.
In this note
Bacterial Ultrastructure - Cell Wall, Structure and Biosynthesis of Bacterial Cell Wall. Bacterial expressions in the Cell Wall structure
Peptidoglycan:
Gram-Positive vs. Gram-Negative Cell Walls
Bacterial Ultrastructure - Cell Wall, Structure and Biosynthesis of Bacterial Cell Wall. Bacterial expressions in the Cell Wall structure
The Bacterial Cell Membrane:
The bacterial cell membrane, also known as the plasma membrane, is a phospholipid bilayer that plays a crucial role in cell wall synthesis and other essential functions.
Composition: The membrane is composed of phospholipids and proteins, but lacks sterols like cholesterol, which are typically found in eukaryotic cell membranes. (Mycoplasmas are a notable exception).
Functions:
1. Energy Production: The enzymes of the respiratory chain are embedded in the inner layer of the cell membrane. In aerobic bacteria, oxidative phosphorylation occurs here, generating ATP for cellular energy.
2. Transport: The cell membrane acts as a selectively permeable barrier, regulating the passage of nutrients, waste products, and other molecules in and out of the cell. Crucial for maintaining osmotic balance and nutrient uptake.
3. Cell Wall Synthesis: The membrane plays a crucial role in the synthesis and assembly of the peptidoglycan layer, which forms the structural backbone of the cell wall.
4. Cell Division: The cell membrane is involved in chromosome segregation and the formation of the septum during cell division.
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