Microorganisms

Hannah Waters
Flashcards by Hannah Waters, updated more than 1 year ago
Hannah Waters
Created by Hannah Waters over 4 years ago
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University Microbiology (Semester 1) Flashcards on Microorganisms, created by Hannah Waters on 06/07/2016.

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Question Answer
What is microbiology? A branch of biology that concerns living things too small to be seen without the aid of a microscope.
What are the beneficial properties of microorganisms? Decomposition Recycling of nutrients Absorption of gases Basis of the food chain For use in experimental procedures
What is the difference between microbiology, immunology and infection control? Microbiology: study of microorganisms Immunology: study of the immune system Infection control: the interventions to reduce the harm caused by pathogens
How are microorganisms classified? Prokaryotic: bacteria Eukaryotic: all other living organisms
How are bacteria classified? Size: average 0.5-2.0um Structure: arrangement and shape Shapes: coccus, bacillus, coccobacillus, vibrio, spirillum, spirochete
What is gram positive bacteria? Thicker, peptidoglycan wall Teichoic acids
What is the structure and function of flagella? Movement
What is the structure and function of pilli Short protein appendages on gram negative Smaller than flagella
What is the structure and function of the capsule? Protects bacteria from drying out
What is the structure and function of bacterial cytoplasm? 80% water, 20% salts-proteins Circular DNA, haploid (grows quicker) Plasmids (extra circular DNA that can replicate independently) No organelles
What is the structure and function of the cell wall? Unique to almost all bacteria Semi rigid structure Gives shape, staining properties and support Peptidoglycan Polymer in cell walls Gram negative, positive or acid fast
What are technoic acids? Found in gram positive bacteria only Provide rigidity Give bacteria antigenic specificity
What are lipopolysaccharides? In gram negative bacteria only Endotoxin or pyrogen (fever causing) Structure- Lipid A, Polysaccharide Toxic: kills mise, pigs, humans Adjuvant: stimulates immunity Heat resistant: hard to remove
What are acid fast bacteria? Have cell wall like gram positive Also covered with thick waxy layer
What is gram staining? Basic classification based on cell wall structure. Gram positive or gram negative. Staining technique that provides easy differentiation into one of two groups.
What is gram negative bacteria? Endotoxin Extra outer membrane
Is gram positive or negative more sensitive to penicillin? Positive
Does alcohol affect gram positive or negative more? Negative
What is the structure and function of the cell membrane? Just below cell wall Phosphlipid bilayer Water can penetrate Flexible Weak, rupture easily -osmotic pressure created by cytoplasm
What are fungi? Can grow in environments where bacteria may struggle Grow in acidic (low pH) and cold envrionments
What are yeasts? Unicellular organisms Ability to grow in two different forms This ability affects ability to invade host tissues
What are protozoa? Single celled organisms (still eukaryotes) Classified according to their abillity to move Sarcondinia - amoebae Mastigophora - flagellates Ciliophora - ciliates Sporozoa - non motile
What are parasites? Derives nutrients from its host Parasitic diseases caused by: protozoa, helminths and arthropods Host will be slightly harmed/killed Most successful maintain life without killing host
What is a virus? Cannot be seen under a light microscope Need living cell to replicate inside (usually causing cell lysis/death) Genetic data of each type is carried as either single or double strands of RNA or DNA Do not respond to antibiotics
What are the requirements for bacterial growth? Physical factors: temperature, pH, osmotic pressure, oxygen Chemical factors: water, carbon source, nitrogen, phosphorous, sulfur, trace elements and minerals Most bacteria are free living however some need to live in a host cell e.g. chlamydia
What are the effects of temperature on bacteria? Pathogenic bacteria prefer 37 degrees Too low and they don't grow Too high and they die
What are the effects of water and osmotic pressure on bacteria? Grow best in wet conidctions Can survive dry but need water to reproduce Best if solution is isotonic (normal) Hypotonic: swell and burts Hypertonic: shrink
What are the effects of oxygen on bacteria? Aerobes need oxygen Anaerobes can't live with oxygen Facultative anerobes can switch between When collecting samples - need to know oxygen status
What is conjugation? Transfer of genetic material from one bacterium to another by means of a sex pill.
What is the structure and replication of an endospore? Form in unfavourable conditions Only in gram positive bacillus Resistant structure Survive for years
What is pathogenicity? The capacity to produce disease
What is virulence? The degree of pathogenicity. Depends on organism
What is an infectious disease? A harmful alteration of physiology or metabolism caused by a microorganism or its products. Caused by a pathogen.
What is a pathogen? A microorganism that can cause disease.
How can bacteria cause disease? Bacteria become established Penetrate defenses Invade tissues Multiply Produce clinical symptoms
What is the difference between exogenous and endogenous infections? Exogenous: from the environment e.g. cross infection in hospital Endogenous: source from within the body e.g. normal flora displaced where they don't normally exist
What is the infective dose? A virulence factor Number of cells required to enter the body to cause disease e.g. 1 tab might lower bp by 10%
What is adherence? The way that bacteria stick to you Particularly those that invade via mucous membranes Body attempts to rid by sneezing or coughing e.g. streptococcus pyogenes attaches to a protein on the surfaces of many human cells
What are pili? A strain of Escherichia coli that attached to surfaces in the bladder and kidneys to cause UTI. The tip of each pilus attaches to single molecules. Some strains of E coli don't have pili and are flushed out with urine
What are slime layers? Secrete sticky stuff and can form multiple layers Sticks the layer of bacteria to the surface
What is biofilm? Multiple layers of slime Also forms on medical decides e.g. catheters Difficult to remove Protected from host defences because glycoclayx forms physical barrier that human defences can't penetrate.
What are toxins? Produced by some microorganisms Interfere with normal functioning of host cells or tissues Directly damage or alter normal cellular processes Not all microorganisms produce toxins Viruses do not produce toxins
What are the two types of toxins? Exotoxins: secreted into the environment in which the bacteria are growing. e.g. food Endotoxins: form part of the outer membrane of gram-negative bacteria. released when bacterial cell is damaged or dies
What is bacterial haemolysis? Red blood cells damaged by toxins
What happens when toxins act as super antigens? Large numbers of T cells are activated Massive release of cytokines Cause injury to host tissues and septic shock Suppress normal immune response -toxic shock
What are toxoids? Toxins modified by heart of chemicals to remove their toxicity but retain ability to elicit an immune response.
What are antitoxins? A specific antibody produced against a toxin Binds to the toxin and neutralises it, preventing it from binding to its target cell Can also treat exotocin diseases with antitoxins that neutralise the toxin already in body With antitoxin patients may die because their immunge system doesn't have time to make required antibodies
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