. Calvin Cycle: - Central pathway for carbon fixation in photoautotrophs. - Converts CO₂ → glucose using ATP and NADPH from light reactions. - Key enzymes : RuBisCO, G3P dehydrogenase, etc. - Importance : Foundation of photosynthetic energy storage. Modern Concepts in Energy Acquisition: - Diversity of metabolic strategies: Chemolithotrophy - Phototrophy - Fermentation - Aerobic/anaerobic respiration --- 2. Principles of Medical Microbiology Historical Contributors of Medical Microbiology : - Louis Pasteur : Germ theory, rabies vaccine. - Robert Koch : Koch’s postulates, TB bacterium. - Joseph Lister : Antiseptic surgery. --- 3. Prokaryotic Cell Structures External Structures : - Capsule : Anti-phagocytic; immune evasion. - Cell wall : Gram-positive : Thick peptidoglycan, teichoic acids. - Gram-negative : Thin peptidoglycan + outer membrane with LPS . - Flagella : Motility. - Fimbriae/Pili : Attachment and conjugation. Internal Structures : - Plasmids : Extrachromosomal DNA; often carry resistance genes. - Ribosomes : 70S. - Nucleoid : Circular DNA. --- 4. Antibiotics and Resistance Antibiotics Overview : - Classes: Penicillins, Aminoglycosides, Macrolides, etc. - Targets: Cell wall, protein synthesis, nucleic acid synthesis. Mechanisms of Resistance : - Genetic transfer : Transformation, conjugation, transduction. - Enzymatic inactivation : e.g., β-lactamases. - Target modification . - Efflux pumps . Types of Action : - Bacteriostatic : Inhibit growth (e.g., tetracycline). - Bactericidal : Kill bacteria (e.g., penicillin). --- 5. Viruses and Pathogenesis Viral Pathogenesis : - Types of infection : Productive : Virus replicates and lyses host. - Abortive : Entry occurs, but no replication. - Latent : Virus remains dormant (e.g., HSV). Latency & Immune Evasion : - Latency : Viral genome persists in host without expression. - Immune escape :Hiding in neurons (e.g., HSV) - Downregulating MHC I - Antigenic variation Importance of Viral Spikes : - Spikes = surface glycoproteins (e.g., hemagglutinin in influenza). - Function : Host cell attachment and entry. - Mutations in spikes → antigenic drift/shift (esp. in flu virus). --- 6. Virology - Specific Topics Retroviruses : - RNA viruses that reverse transcribe into DNA (e.g., HIV). - Viral latency : Integration into host genome. - Immune evasion via antigenic variation and hiding. Phages : - Bacteriophages = viruses that infect bacteria. - Can transfer resistance genes. - Used in phage therapy. --- 7. Antiviral & Antiretroviral Drugs Antiviral Drugs : - Target various stages of viral replication: Entry inhibitors - Uncoating inhibitors - Nucleoside analogues (e.g., acyclovir) - Protease inhibitors Antiretroviral Therapy (ART) : - Used in HIV treatment. - Common classes: Reverse transcriptase inhibitors (NRTIs, NNRTIs) - Protease inhibitors - Integrase inhibitors - Entry inhibitors --- ---