Bacterial Structure & Function & Virulence | Alison Weiss | 01/21/25 Notes Part 1

  • What is a disease? A change from general good health, involving disruption of normal structure or functioning of body causes by not good nutrition, genetic abnormalities, structural or functional disorders, & trauma 

  • What are some examples of infectious diseases? Prions, viruses, bacteria, fungi, (protozoa) 

  • What are prions? Single protein very small 

  • What are viruses? Average about 100 nanometers, have few proteins, must commandeer the machinery of the cells they invade to reproduce

  • How are bacteria sizes compared to one another and what is bacteria? Vary, but at least 10x bigger than viruses & single cell organisms & can reproduce independently 

  • How do single-cell parasites compare to bacteria? At least 10x larger than bacteria

  • How big are multicellular parasites? So large they can often be seen with the naked eye, tapeworms can be 20 feet long 

  • What are the 3 types of life? Archaebacteria, Eukaryotes, and usually Eubacteria too but not here because it is a challenge of selective toxicity 

  • Eukaryotes divide into 2 groups called? Eubacteria & Archaebacteria 

  • What is Eubacteria? Include bacteria of medical importance

  • What is Archaebacteria? A collection of evolutionary distinct organisms; primarily found in extreme terrestrial & aquatic environments 

  • How do eukaryotes groups affect selective toxicity? CHECK w 

  • In therapeutics where do antibiotics work? Cell wall and cytoplasm (internal)

  • Where do antibodies/vaccines work? Cell-surface (external)

  • What does PAMPS stand for? Pathogen-Associated Molecular Patterns

  • What is PAMPS and what does it do? Conserved structure on microorganisms includes cell wall structures of bacteria + genetically encoded to be recognized by innate immune system, PAMPS jump-starts the immune response + induce inflammation, cytokine release, sepsis + can cause symptoms of disease in the absence of living bacteria

  • What are the differences between Prokaryotes (Bacteria) and Eukaryotes? nucleoid or nucleus, circular and/or linear or linear chromosomes, no membrane bound organelles or yes like Goldi+ER+mitochondrion+chloroplast, present in most species w peptidoglycan or present in fungi+plants, usually no sterols/cholesterol or yes sterol.cholesterol, 70s or 80s 

  • What does the bacterial cytosol contain? Contains enzymes that generate ATP, cell wall, RNA, DNA

  • Prokaryotic (70S) ribosomes are found throughout where? Cytoplasm and on membrane

  • Where is the DNA found? Cytoplasm, supercoiled so that it is manageable size

  • What does the cell wall determine? Shape and species property 

  • What are the 3 main shapes & names? sphere=cocus, rod-bacillus, & spiral or curved=spirochete or vibrio

  • What does the cell wall made of peptidoglycan do? Protects from environmental stress, provides strength, maintains shape, & limits penetration of molecules

  • What is the medical importance of cell walls? Protects from some host defenses & role in adherence to host cells

  • What is selective toxicity unique to? Bacteria, target for many antibiotics

  • What is the gram stain procedure used to classify and what is it? Bacteria & it consists of fixation, crystal violet, iodine treatment, decolorization, & counter stain (safranin)

  • What is the primary difference between gram positive and gram negative? Gram positive retain crystal violet so it’s purple & gram-negative only stained by safranin so it’s red

  • What are the characteristics of gram positive? 1 membrane, 40 layers of peptidoglycan (trait that determines retention of gram stain), & lipoteichoic acid

  • What are the characteristics of gram negative? 2 membranes, 1 layer of peptidoglycan, & Lipopolysaccharide 

  • What is Peptidoglycan made of? Highly cross-linked mesh of peptides & polysaccharides 

  • What do antibiotics attack and what are some examples? Cross Linking, such as penicillin, cephalosporin, & vancomycin 

  • What is the structure composed of in gram positive? Multiple peptidoglycan layers & lipoteichoic acid near inside & Teichoic acid near outside (PAMP)

  • What is the structure composed of in gram negative? Porin (entry of small molecules), Lipopolysaccharide (PAMP), outer membrane, periplasmic place, 1 peptidoglycan layer, plasma membrane 

  • What are bacterial capsules? Prevents penetration of dye + usually carbohydrate + located outside of bacterial cell wall

  • What are the functions of a capsule? Protection from harsh environment, permeability barrier, surface attachment (including hot tissues), anti-phagocytic 

  • Capsule is often associated with what? Pathogenicity; encapsulated=virulent & no capsule=avirulent 

  • Capsules are what & what does that mean? Antigenic, can induce protective antibodies that promote engulfment by phagocytes

  • What does the capsule protect the bacterium from? Phagocytosis, antibody to capsule promotes uptake so bacteria eliminated by phagocytosis

  • What is the term for surface appendages and what’s the structure of it? Flagella which are rope-like filaments of coiled protein subunits called flagellin & made of hook & basal body

  • What are flagella involved in? Bacterial movement (motility)

  • What is chemotaxis composed of? Nutrients, sugars (humans)

  • What is the role of motility in pathogenesis? It mediates tissue invasion so it traverses cellular/extracellular barriers, chemotaxis where swimming through intestinal music barrier, access intestinal cells, & breach skin barrier

  • What are Pili-Surface Appendages & what are they involved in? Present over entire surface made of protein (pilin), transformation (uptake of naked DNA) so promotes bacterial movement, serve as phage receptors, & anti-phagocytic

  • What is Pap Pili associated with? E-coli that causes urinary tract infections

  • What is the model of Pilus Assembly composed of? About 200 pili per cell, 100 proteins per pilus, 6 structural genes, & 5 genes for assembly and secretion

  • What is Sporulation? Mechanism to insure survival during adverse conditions triggered by nutrient deprivation, not a reproductive stage, 1 bacterium makes 1 spore

  • What does the free endospore revert back to? Vegetative cell (germination) when it encounters favorable conditions for growth

  • Spores are resistant to killing by what? Heat over 2 hours of boiling, drying, freezing, pH extremes, deleterious chemicals, antibiotics, radiation

  • What are sterilization procedures? Bleach & autoclaving (exposure to high temp + pressure)

  • What influences disease severity as in what's its formula? (virulence*pathogen dose) / (health status*immune response)

  • How would seasonal flu, covid-19, and ebola rate lowest to highest in death rate (virulence)? Flu, covid-19, then ebola

  • What are some underlying conditions that could impact health status? Diabetes, chronic lung disease, cardiac disease, & age equal or over 65 years old

  • Does Immune Response reduce or enhance disease? both

  • What does a high pathogen dose look like? Health care workers are constantly exposed, get very close to highly infectious people

  • What are the 5 steps in the pathogenic process? Infect the host, grow and spread, evade defenses, damage host, & transmission

  • Steps 1-3 of the pathogenic process are called what? Normal microbiome

  • Steps 1-4 of the pathogenic process are called what? Pathogens (virulence factors)