MicrobiologyIntroduction to Microbiology1. What are the 4 basic groups of pathogens?12. What is the purpose of a ﬂagella and which basic sub group has them? 23. What is the purpose of pilli?34. Why is penicillin effective only against foreign organisms (not host cells)? 45. What are the rough diameters/lengths of: an erythrocyte, E.coli, staphylococcus, viruses, parasites56. What is a nucleocapsid?67. What are rods and cocci?78. What do gram positive and gram negative signify?9. What other differences are there between gram negative and gram positive? 810.TB bacteria do not have a positive or negative gram stain, so how are they identiﬁed?91 Bacteria, Fungi, Viruses, Parasites2 Movement or sensitivity (to temperature and chemical changes), some bacterial have ﬂagella3Pilli are hair like organelles found on many bacteria, they are used to attach to host cells (in the case ofpathogenic bacteria) and are also the targets for B cells to latch onto during immune response4 Because it attacks the bacterial cell wall which host cells donʼt have5Erythrocytes (Red blood cells) are 8 micro metres, E coli 2-3 micrometres, Staphylococcus Aureus 1 micrometre, Viruses 20-300nano metres, parasites can be metres long in the case of worms6A nucleocapsid is the basic unit of a virus, it is the capsule within which the viral DNA is carried and manycan be released from a host cell to replicate the virus.7 These are used to signify whether a bacteria is long and thin (rod) or round like an ʻeyeʼ (cocci).8Gram positive survive drying, some produce spores and have teichoic acid in their cell walls. Gramnegative do not survive drying and have endotoxin in their cell walls, they do not produce spores.9 ZN stain
11.What causes peritonitis?1012.List the primary and secondary lymphoid organs1113.Roughly how many are there of the following cell types in the body per ml of blood: white blood cells overall, neutrophils, lymphocytes, monocytes12Collagen Synthesis and Disorders1. What deﬁnes something as a collagen? 132. What are collagens type 1, type III, type IV and type VIII? Which are ﬁbrillar and which are non-ﬁbrillar? 143. How does the collagen helix differ structurally from the DNA helix?154. What needs to happen to proline for it to support the collagen structure? 165. What chemical structural difference exists between alpha 1 and alpha 2 chains?176. What causes collagen to have tensile strength?187. Is a mutation in collagen more dangerous if it is close to the ribosome, or away from it? and why?1910 A ruptured spleen or appendix allows harmful gut bacteria to get into the organ, causing infection.11 Primary: Bone marrow, thymus (T-lymphocytes must pass through here). Secondary: 50-200 lymph nodesthroughout the body, spleen, Peyerʼs patches in the gut white blood cells overall (4-7 million/ml), neutrophils (2-4 million/ml), lymphocytes (1-2 million/ml),12monocytes (0.2-0.5 million/ml)13Anything with the amino acid sequence glycine-x-y (with x usually being proline and y hydroxyproline),collagens are ﬁbrous and insoluble14Type 1 = most abundant (90%) found in bone, Type 2 = cartilage, Type 3 = found in extensible tissue suchas lung, foetal skin, vascular system, Type 4 = basal lamina of epithelium, structurally kinked so partiallypermeable (Types 1-3 are ﬁbrillar, 4 is non ﬁbrillar)15 Unit of collagen is a loose helix because it has 3 amino acids per turn of the helix whereas DNA has 4, thisis because glycene is the smallest amino acid. The basic unit of collagen is tropocollagen (2 alpha 1 and 1alpha 2 chains). Collagen gets its tensile strength because the helix cannot be undone in a single movement.16 Proline and lysine must be hydrolysed to provide structural support for collagen, doing this requires vitaminC17Alpha 1 contain glycoproteins and disulphide bridges at the outward ends of the structure, Alpha 2 lackthese18Collagen gets its tensile strength because the helix cannot be undone in a single movement. Individualhelixes must be left handed whereas triple helix right handed.19 Mutation nearest the ribosome is most dangerous since the collagen chain is synthesised from theribosome outwards and therefore a mutation here will affect the whole chain from that point onwards
8. Lysyl hydroxylase is also required for the formation and support of collagen, how is it activated?209. What structural modiﬁcation makes the basic unit of tropocollagen into collagen type 1?2110.In which type of collagen are the ends not trimmed? 2211.Give examples of a heritable collagen disease and an environmental one2312.What are the symptoms and cause of osteogenesis imperfecta?2413.What are the types and effects of Ehlers’ Danlos Syndrome? 2514.Which collagen disease is a competitive inhibitor to lysine oxidase?2615.What is Cu2+ needed for in collagen synthesis?2716.What does scurvy do in terms of collagen?2817.Which collagen diseases affect collagen types II, X and XI and therefore cartilage? 29Bacterial Pathology20Lysyl hydroxylase is responsible for the hydroxylation of lysine to lysine hydroxylase and is activated bythe reduction of Fe3+ to Fe2+, which requires vitamin C21The loose ends are trimmed (COO- at the ribosome and +H3N at the outward end) leaving the centralhelical chain22 Collagen type 4 since it needs the ends to provide gaps in its looser structure23 Heritable (genetic): Osteogenesis imperfecta, Environmental (source): Vitamin C/Copper deﬁciency24An autosomal dominant heritable condition (50% chance if parent sufferer) which causes brittle bones,caused by substitution of glycine in collagen with another amino acid25 ED type 4 affects collagen type 3 which is used in extensible smooth muscle, can lead to aortic rupture.ED type 3 affects collagen in joints (type 2) and leads to hyper-mobility of joints and later arthritis.26 Lathyrism27 Needed in activation process of lysine oxidase along with vitamin C28Scurvy is Vitamin C deﬁciency, vitamin C is crucial in the activation of lysyl hydroxylase because it reducesFe3+ to Fe2+, without lysyl hydroxylase collagen cannot be synthesised or stabilized.29 Chondrodystrophies
1. What are the three classes of bacteria in relation to how infective they are and what characterizes them?302. What is the name of the bacteria found commonly on everyone’s skin?313. Which bacteria are the most commonly found in gut ﬂora?324. What is a subclinical infection? 335. What is a localised infection (give examples)?346. What are the most dangerous toxins produced by Staphylococcus Aureus and what do they do?357. What is the toxic mechanism of septicemia?368. What happens in toxic shock syndrome?379. What sort of ‘host responses’ can be signs of infection? 3810.Why would giving antibiotics to a meningitis patient worsen the condition initially before ultimately curing it? 3930 Commensal = normal generally harmless colonies & ﬂora, Opportunist = mostly harmless ﬂora but cancause infection if they get into the wrong places, Pathogenic = primarily cause diseases (e.g. TB), nobody isa ʻnormalʼ carrier31 Staphylococcus Epidermis32 E. Coli33An infection which does not cause severe/noticeable symptoms e.g. being a carrier of the common cold orchickenpox (can have this as a symptomless infection as a child)34An infection which is self limiting and can only affect a particular area of the body, e.g. sore throat,diarrhea, rarely progress to systemic infection35Coagulase enzyme (converts ﬁbrinogen into ﬁbrin and results in the clotting of blood) and PVL (kills whiteblood cells and allows infection to take hold further)36 Produces endotoxin which damages cell walls, toxin invades blood and has 1/3 mortality rate37 Bacterial toxins produced by S. aureus or S. pyogenes called superantigens allows the nonspeciﬁc bindingof MHC with T cell receptors resulting in up to 20% of the bodyʼs T cells being activated against host tissuescausing multiple system failure.38Cytokines produced, antigens presented to T cells, histamine release, neutrophils excreted to area andincreased blood vessel permeability.39They increase the level of ʻbacterial productsʼ in the system. Immune symptoms increase againstantibiotic. Sometimes steroids are given in conjunction with the antibiotic to lessen this effect.
11.What is the biological mechanism of fever?40Viral Infection1. What is ‘tropism’?412. What is the difference between active and passive immunity? 423. What deﬁnes an ‘obligate intracellular parasite’? 434. What is the size range for viruses?445. What are the basic structural features of a virus? 456. How are viruses detected in the lab? 467. What categories might viruses be classiﬁed by? 478. What needs to happen to -ve sense stranded viral RNA to replicate? 489. Give 2 examples of DNA based viruses and say whether they are enveloped or non-enveloped4940Increased cytokine production, effect on hypothalamus (thermoregulation) and prostaglandin E2production in hypothalamus41Tropism refers to what types of cell the virus can get into. In terms of invasiveness, can they break downbarriers/membranes to get into cells.42 Active is developing your own immunity in response to pathogen exposure. Passive is inherited immunityi.e. fetus inheriting maternal antibodies or by antibody transfusion in immunodeﬁciency43 An obligate intracellular parasite is a virus. They can only grow inside ʻhost cellsʼ and invade cells viaeither DNA or RNA based mechanism and express receptor binding proteins for antibodies as well aspotential cells to invade.44 20-300nm45 All viruses contain a DNA or RNA core which is surrounded by a capsule forming a nucleocapsid. Manyviruses also have a virus envelope studded with glycoproteins. The viral envelope usually originates from aninvaded host cell. Non-enveloped viruses are better at surviving in harsh environments such as the GI tract,as the envelope makes them more susceptible to chemical attack a lipid bilayer also means the virus maydry up.46 Either serological techniques (identiﬁcation of virus speciﬁc antibody in the plasma.47Enveloped or non-enveloped, RNA or DNA based, number of strands (one genome or segments), +ve or -ve sense strand.48Needs to be changed to +ve sense stranded. Many -ve stranded DNA contain ssRNA dependent RNApolymerase to make +ve stranded. Double stranded viruses contain double stranded RNA dependent RNApolymerase. Retroviruses (HIV) contain reverse transcriptase.49Parvoviridae (non-enveloped), papovaviridae (non-enveloped), hepandnaviridae (Hepatitis, enveloped),adenanridae ((non-enveloped), herpesviridae (enveloped)
10.Give 2 examples of DNA based viruses and say whether they are enveloped or non-enveloped5011.Which cells/molecules does the Inﬂuenza virus affect? 5112.Which cells/molecules does Rabies affect?5213.Which cells/molecules does HIV invade?5314.Which cells/molecules does Epstein Barr virus invade? 5415.Which cells/molecules does Reovirus (not rhinovirus) attack? 5516.Describe the 6 main stages in a cycle of lytic viral infection/replication5617.What is latent infection?5718.What is the acute phase of infection? 5819.What deﬁnes chronic infection? 5950Picorna viridae (non-enveloped), thomyxoviridae (enveloped), paramyxoviridae (enveloped), retroviridae(enveloped)51 Salic acid on glycoproteins52 Acetylcholine A53 T cells, causing failure of immune response54 B cells, causing failure of immune response55 B-adrenergic hormone receptor56 1/ Replication (synthesis of DNA), 2/Assembly of capsids containing nucleic acid, 3/Release of capsidsfrom cell, 4/Binding of capsids to receptors on new cell, 5/Penetration of new host cell by membrane fusion/phagosome uptake, 6/Uncoating, capsids release RNA/DNA57 Virus persistence after initial clearance at which point the infection may become asymptomatic58The acute phase describes rapid replication of the virus after initial infection when symptoms are mostobvious59Chronic infection is when a virus may stay in the system in large numbers for an extended period withoutcausing a symptom/disease episode