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Description
Flashcards by Fern Chipperfield, updated more than 1 year ago
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Created by Fern Chipperfield
over 9 years ago
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| Question | Answer |
| Give an example of a microbiological agent of food borne diseases. | Toxic Algae-can go down food chain to shellfish Protozoa- Group of single celled microscopic animals Parasites- an organism which lives in or on another organism and benefits by deriving nutrients at thier expense. |
| What is a mycotoxin? | Any substance produced by a fungus. |
| What components are in a bacteria cell? | .Cell wall=peptidoglycan .Cytoplasm .Nucleoid (DNA) .Ribosomes .Cytoplasmic membrane |
| Bacteria come in 2 different shapes. What are these 2 different shapes? | .COCCI-spherical bacteria- in chains, grape like clusters, pairs,in cubes of cells .RODS-short or long- singly- in filaments of attached cells Bacteria also come in different sizes |
| Names tell you about the bacteria. What does staphylococcus aureus and streptococcus pneumoniae tell you? | Aureus-Gold Pneumoniae=lungs |
| How are Chromosomes present in a bacteria cell? | Chromosomes are wrapped up but not in histone protiens E.coli chromosome length=1.3mm E.coli cell length=1.7um DNA density in cell=10mg/ml |
| What is an endospore? | .some bacteria produce this reproductive structure .spore has lots of layers around the genetic material=very resistant |
| What are endospores resistant to? | .Heat .UV radiation .Chemical disinfectants .Drying |
| How can endospores be killed? | sterilization removes the layers but takes a very long itme Treatment at 121 degrees for 15 minutes |
| what are the components of an endospore ? | |
| Label a bacteria cell | |
| What are the functions of these components? .Flagellum .Pillus .Cell wall | Flagellum---> movement Pillus----> attaching Cell wall ----> stops the cell from bursting due to osmosis |
| What is the difference between gram negative and gram positive? | Gram postive=Purple Gram Negative= pink Due to differences in cell structure |
| what extra layers does gram negative have than gram positive? | gram negative=has an additional outer membrane containing lipopolysacchardies another layer of polysaccharide or protien making up a capsule or slime layer layers external to the outer membrane referred to as the cell envelope. |
| what do endotoxins cause? | Endotoxins cause a septic shock when introduced into the bloodstream. |
| How do bacteria grow and divide? | Binary Fission 1. Synthesizes new cell consituents 2. Grows in size 3.Replicates its genetic material 4. A new cell wall is formed 5.The cell divides into 2-septum forms |
| What is the name of bacteria that grow in liquid? | Planktonic |
| What is the name of bacteria that grow on surfaces? | Sessile |
| What is the name of bacteria growing on surfaces as an organised community? | Biofilms |
| What do each of the line of the graph represent? What type of growth does this show? | 1. lag phase 2. exponential phase 3. stationary phase Type of growth=exponential growth |
| Define 'Doubling time' | The time taken for the number of cells in a population to double. |
| Define 'Chemoorganotroph'. | Bacteria that use organic chemicals such as glucose and acetate. |
| Define 'Chemolithotrophs'. | Bacteria that use inorganic chemicals e.g H2,H2S. |
| Define 'Phototrophs'. | Organisms that use sunlight as a source of energy. |
| Define 'Heterotrophs'. | Bacteria/fungi that use organic products such as glucose,amino acids etc. |
| Define 'Autotrophs' | Microbes capable of fixing carbon e.g CO2 and then using it to make cellular components. |
| What agar should be used for fastidious pathogenic organisms? | Blood agar |
| What temperatures do each listed prefer? 1.Psychrophiles 2.Psychrotolerant 3.Mesophiles 4.Thermophiles 5.Hyperthermophiles | 1.low temperatures 0-25 2. 25-30 3.Body temperature 15-45 4.30-75 5. very high temperatures >100 |
| Define Aerobes. | Capable of growing in the presence of oxygen. |
| Define anaerobes. | Bacteria that do not require oxygen for growth. |
| Define Facultative Anerobes | prefer oxygen but can grow anaerobically. |
| Define Obligate Anaerobes. | Die in the presence of oxygen. |
| Define Aerotolerant | Anaerobes that ignore the presence of oxygen and grow equally well in its presence or absence. |
| Define Microaerophillic. | Damage by normal atmospheric concentractions of 20% and only survive at much lower concentrations. |
| What pH range does an acidophile live in? | 0-5.5 |
| What pH range does an alkaliphile live in? | 8.5-11.5 |
| Water availablity is important, what conditions do this live in? 1.Halophile 2.Halotolerant 3.Osmophiles 3.Xerophile | 1.Grow at high salt concentration 2.Capable of growing in 3M nacl 4.Likes high osmolarity 3.Able to grow in dry environments |
| How can we stop microbes from growing? | Control temperature Remove water Use extreme pH's Control oxygen availabilty Add substances to prevent growth |
| Define 'Sterilisation'. | Total destruction of all microbes. |
| Define 'Disinfection'. | Removal of microbes using physical or chemical means-does not necessarily involve all microbes. |
| Define 'Antiseptic'. | Use of chemical agents on skin or living tissue. |
| Define 'Bactericidal'. | Kills bacteria |
| Define 'Bacteriastatic'. | Inhibits growth |
| Define 'sporocide'. | Kills endospores |
| Give some examples of foods you can food bourne dieases from. | Chicken=Camplylobacter Jejuni Eggs=salmonella Strawberries= Hepatitis A virus Ready to eat meats= Listeria |
| Which disinfectants and antiseptics kill evrything but endospores and some virses? | Alcohol 70% Phenoilics |
| Which disinfectants and antiseptics kill everything though some spores may survive? | Hydrogen peroxide and chlorine |
| Which disinfectant and antiseptics kills everything? | Formaldehyde |
| What factors influence effectiveness of disinfectants? | .Number of microbes .Type and concentration of disinfectant .Duration of exposure .Temperature of exposure |
| Name a potential target site | .Peptidoglycan .Ribosomes .Nucleic acid synthesis |
| What does MRSA stand for? | Methicillin-resistant staphylococcus aureus |
| Who is at risk of infections? | .Very Young .Old .People that are already ill .Malnourished .Those in poor housing |
| To cause infection bacteria must beable to: | .Spread between hosts .Reach their prefered site in the body .Grow and multiply .Avoid the host immune response .Leave the host |
| How can a host prevent against infection? | 1. Prevent access- skin,mucus 2.Prevent replivation Prevent nutrient acqusition neutralise microbe or its products 3. Get rid of it |
| How can Bacteria reach different places? | The epithial surface Invasion though th mucosal surfaces Direct injection into blood stream Though wounds Canulas |
| What are the defense mechanisms on mucosal surfaces? | .Mechanical barriers-skin,Mucosal membranes-prevents microbial penetration .Flushing-Tears,Urine,Saliva,Coughing .pH-Stomach acidity,fatty acids on skin .Lysozyme=Breaks down peptidoglycan in bacteria |
| What is the role of Commensals? Natural Flora | .Metabolism of food products .Production of essential growth factors .protects against infection .Stimulate the immune response |
| Define 'Virulence factors'. | Features of the bacterium that help it infect and cause disease. Virulence factors help the bacteria get to the prefered site and survive on the way there. evade host defense mechanisms-cell surface feactures,stay there and multiply,cause damage-toxins and enzymes etc |
| Name some virulence factors. | .Flagella-movement .Mucinases and proteases-enzyme that breaks down protiens and peptides- hydrolyses Mucins (a component in Saliva) .Ciliostatic protiens-inhibition of cilial movement |
| Name the virulence factors in cholera. | Flagella-motility and chemotaxis-penetrate mucus pili and haemagglutinins-adherence to gut mucinase and protease-degrade mucus Enterotoxin-stimulates adenyl cyclase resulting in the secreation of fluid into the gut. |
| How does typhoid get in? | .Penetrate gut mucosa .reach lymph nodes .survive and multiply in macrophages .Transported in macrophages to bloodsteam .Reach spleen,liver,bone marrow,Peyers Patches |
| What are some symptoms of gut infections? | .Diarrhoea leading to dehydration .Bloody diarrhoea .weight loss .Sudden onset of nausa,vomiting,diarrhoea .Fever |
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