MICR 3330 Final exam examples questions and answers solved

Staphylococcus is gram positive or negative - Correct Answers positive Corynebacterium is gram positive or negative - Correct Answers positive Burkholderia is gram positive or negative - Correct Answers negative Yersinia is gram positive or negative - Correct Answers negative Neisseria is gram positive or negative - Correct Answers negative Streptococcus is gram positive or negative - Correct Answers positive Pseudomonas is gram positive or negative - Correct Answers negative Vibrio is gram positive or negative - Correct Answersnegative 3 Sources of iron - Correct Answerstransferrin (liver), lactoferrin (mucus), haemoglobin (RBC) 3 mechanisms of iron uptake( + iron source) by bacteria - Correct AnswersHemolysin (iron source heme), Siderophores (iron source transferrin and lactoferrin), direct contact (transferrin and lactoferrin) Hemolysin is used by - Correct Answerssystemic E. coli produces alpha haemolysin Siderophores used by - Correct AnswersE. coli, Pseudomonas, Yersinia How is iron siderophore complex taken into cell - Correct AnswersEnergy coupled OM transporter TonB What are 2 main types of siderophores in E.coli - Correct Answersenterobactin (a catechol) , aerobactin (a hydroxamates) What bacteria use direct contact iron uptake - Correct AnswersNeisseria and Haemophilus Motility is a virulence factor for 4 bacteria - Correct AnswersHeliobacter pylori, Vibrio cholera, Salmonella, Campylobacter Define bacterial virulence factors - Correct Answersmolecules produced by bacteria, or strategies used by bacteria that cause disease A pathogen in general must be able to 6 - Correct AnswersColonise (attach to hosts cells) Evade and persist (the hosts immune system) Obtain nutrients (iron) Invade and disseminate (within the host) Produce disease symptoms Be transmissible List 2 bacterial virulence factors - Correct AnswersIron acquisition, motility Why do nearly all bacteria require iron - Correct Answerstrace element in respiration and co-factor in many enzymes For bacteria the result of iron deprivation or extreme iron deficiency is - Correct Answersdeprivation - bacteriostatic Extreme deficiency - bactericidal Bacteria genus that doesn't need iron for growth (disease it causes) - Correct AnswersBorrelia burgdorferi (Lymes disease) Mammalian iron binding proteins - Correct AnswersTransferrin - made in liver the serum protein responsible for iron transport in blood and tissue Lactoferrin - secreted at mucosal surfaces, found in milk, saliva, tears Haemoglobin (containing heme)- most of the bodies iron, in RBC 3 main mechanisms of iron uptake in bacteria and their iron source - Correct AnswersHemolysins - heme Sidophores - transferrin and lactoferrin Direct contact - transferrin and lactoferrin How do haemolysins work, give example bacterium - Correct Answershaemolysin lyses RBCs, haemoglobin digested and heme assimilated , systemic E.coli produce a-haemolysin (non-invasive E. coli do not) What is pneumolysin, what bacterium has it - Correct Answersbinds and disrupts cholesterol in host cell membranes, Streptococcus pneumonia Define siderophores, what are the 2 main chemical groups, and example for each chemical group - Correct AnswersLow molecular weight compounds that chelate (bind) iron with very high affinity Catechols - eg E. coli -enterobactin siderophore Hydroxamates - E.coli - aerobactin siderophore Describe the process of siderophores (secretion to regulation) - Correct AnswersSecreted via T1SS Complexes with FE3+ removing it from host protein (siderophores higher affinity for iron) Iron-siderophore transported into bacterial cell Iron release from complex as FE2+ via ferric reductase Siderophore degraded by protease Siderophore and transport proteins regulated by iron levels Describe the siderophore transport, What type of transporter, where does the energy for FeEnt (ferric enterobactin) to cross from the IM to OM come from - Correct AnswersEnergy coupled OM transporter Transmission of energy from IM to OM is done via TonB protein - TonB rotates, powered by PMF, that promotes conformational change of the IM transporter so the FeEnt can pass through the ABC transporter in the PM Is siderophore production a bacterial virulence factor - Correct AnswersYes for E. coli, Pseudomonas, Yersinia No for Vibrio cholerae- can diffuse ferrous iron across OM via porin channels What are the differences between E.coli enterobactin and aerobactin siderophores - Correct Answersenterobactin- slowly induced, higher affinity, not re-usable aerobactin_ rabidly induced, lower affinity, re-usable What does direct contact iron uptake require - Correct Answersspecific receptors on the membrane for transferrin or lactoferrin 2 bacteria genera that have direct contact iron uptake mechanism - Correct AnswersNeisseria and Haemophilus Explain the function the iron uptake proteins TbpA - Correct AnswersTbpA- binds ferrated and non-ferrated transferrin with equal affinity and is the pore through which iron enters the cell Explain the function the iron uptake proteins TbpB - Correct AnswersTbpB - bind only to ferrated transferrin increasing the efficacy of iron uptake by TpbA. It's a fishing rod that grabs iron loaded transferrin and brings it close to TbpA Explain the function the iron uptake proteins FbpA - Correct AnswersFbpA - ferric binding protein, for periplasmic transport of iron Explain the function the iron uptake proteins FbpB - Correct AnswersFbpB - a permease, plasma membrane transport of iron, an ABC transporter Give 4 examples of bacteria where motility is a virulence factor - Correct AnswersHeliobacter pylori, Vibro cholerae, Salmonella, Campylobacter What rotation direction leads to run and tumble - Correct AnswersCounterclockwise - run, Clockwise tumble What is chemotaxis - Correct Answersdirected movement towards an attractant or away from a chemical repellent What is random walk - Correct Answersrun followed by a tumble, random direction, no nutrient gradient What is a biased random walk, what is it also known as - Correct Answersfewer tumbles, longer runs when moving up gradient towards nutrients, also known as positive chemotaxis Describe Heliobacter pylori motility and its role in virulence, how does it colonise the gut - Correct AnswersCauses inflammation in stomach lining Cells are spiral, move in corkscrew motion using flagella Flagellum negative mutants are unable to colonise stomach Uses urease to protect it from stomach acid Are attracted to epithelial layer swim via positive chemotaxis Adheres to gastric mucosa Bacteria that penetrate mucous layer via motility - Correct AnswersVibrio cholera, Heliobacter pylori Bacteria that penetrate mucous layer via mucinase - Correct AnswersVibrio cholera, Shigella flexneri Bacterial adhesions adhere to 2 - Correct Answerssugar moiety receptor of epithelial cells - glycoproteins, glycolipids What is Pap, what is it associated with - Correct Answerspyelonephritis associated pili - associated with UPEC uropathogenic E.coli - UTIs Composition of a pili 2 - Correct Answerspilins and adhesive subunits