BIO411 Exam 3 & Final Exam Review PDF

Microbial Mechanisms of Pathogenicity (Part 1) continue 1. ​ What is A-B toxin? (is it endotoxin or exotoxin, which subunit bind to cell/cell receptor) The intracellular targeting toxins comprise two components: ​ ​ A for activity ○​ Once toxin is inside the vacuole, the...

Microbial Mechanisms of Pathogenicity (Part 1) continue 1. ​ What is A-B toxin? (is it endotoxin or exotoxin, which subunit bind to cell/cell receptor) The intracellular targeting toxins comprise two components: ​ ​ A for activity ○​ Once toxin is inside the vacuole, the A component separates from the B component and gains access to the cytoplasm ​ B for binding ○​ The B component binds to the host cell through its interactions with specific cell surface receptors. ​ Toxin is brought in through endocytosis. These types of toxins are known as A-B exotoxins. Example: Diphtheria (A-B toxin) ​ Caused by Corynebacterium diphtheria (gram-positive rod; pleomorphic). ​ Forms a tough grayish membrane in the throat ○​ Fibrin and dead tissue ○​ Blocks passage of air to the lungs. ​ Prevented by DTaP vaccine (diphtheria, tetanus, and whooping cough (pertussis)). 2. ​ How Tetanus (Clostridium tetani) and Botulism (Clostridium botulinum) cause disease, where you can see the Spastic paralysis and where Flaccid paralysis. Tetanus - Clostridium tetani Tetanus is another neurotoxin that has a light A subunit and heavy protein chain B subunit. ​ Toxin binds to inhibitory interneurons, which are responsible for release of inhibitory neurotransmitters glycine and gamma-aminobutyric acid (GABA). ○​ Neurotransmitters bind to neurons - result in release of acetylcholine. ​ Toxin inhibits the release of glycine and GABA from the interneuron, resulting in permanent muscle contraction.  ○​ 1st symptom: stiffness of the jaw (lockjaw); violent muscle spasms in other body parts follow, culminating with respiratory failure and death. Botulinum (botox) - Clostridium botulinum Botulinum is the most acutely toxic substance known to date, which is composed of a light subunit A and heavy protein chain B subunit. ​ Subunit B binds to neurons to allow botulinum toxin to enter the neurons at the neuromuscular junction. ​ A subunit acts as a protease, cleaving proteins involved in the neuron’s release acetylcholine to induce muscle fiber contractions. ​ Toxin’s ability to block acetylcholine release results in the inhibition of muscle contractions, leading to muscle relaxation. ​ Has the potential to stop breathing and cause death. 3. ​ Know about other exotoxins (big picture) how they cause disease Exfoliative Toxin (ETs) - Staphylococcus aureus: protein toxins that cause skin blistering and exfoliation by attacking the epidermis of a host cell. -​ Hair folliculitis/boil (furnacles) -​ Impetigo -​ Cellulitis: Staphylococcal scalded skin syndrome Exotoxin A (ETA): a potent bacterial toxin produced by the bacterium Pseudomonas aeruginosa that can be lethal to humans and animals. -​ Inhibits protein synthesis -​ Causes direct cytopathic effects -​ Interferes with the host’s cellular immune functions Leukocidin: 4. ​ Does Strep throat or Scarlet fever are related to each other? Microbial Mechanisms of Pathogenicity (Part 2: Viruses) 1. ​ Know broad understanding regarding how Virus cause disease. 2. ​ Know which two cells HIV virus infect. 3. ​ Know how HIV virus changes CD4/ CD8 cell ratio. 4. ​ Know that polio virus is transmitted by the ingestion and cause the disease by direct damage to the neuronal cell (replicate in the cell) 5. ​ Rabies virus is transmitted by bite (bite with infected animal): virus cause inflammation in nerve cells (encephalitis) and change is activity. 6. ​ Know how a virus cause immunosuppression? (big picture) 7. ​ Know how a virus can cause cancer? (big picture) Chapter 9: The Control of Microbial Growth · ​ Know the definitions of Sterilization, Disinfection, Antisepsis, Sanitization, pasteurization, Biocide, Bacteriostasis. · ​ Know different methods of bacterial control: (how they kill the bacteria, denature protein, denature plasma membrane, etc? ( as Moist Heat/dry heat, filtration, Chemicals: Phenol, halogens, alcohols, Quaternary ammonium compounds, Aldehydes, Ethylene oxide) · ​ Know the condition of the autoclave? Chapter 10. Antimicrobial Drugs · ​ What should be the quality of a good antibiotic? (less toxic to host, more toxic to bacteria) · ​ What is Chemotherapeutic index? · ​ Know the antibiotics and their target in bacteria (where they act) For example: Cell wall: Penicillin, ü Cell membrane: polymyxin ü Bacterial Metabolites (e.g. Folic acid): sulfonamide, ü Protein synthesis (30S ribosomal protein): Gentamycin, ü Protein synthesis (50S ribosomal protein): chloramphenicol ü Bacterial DNA: Quinilones ü Bacterial RNA: Rifamycins Good Luck with your final (December 10, 2024, 12.20- 2.10 pm)