Flashcards
Microorganisms
Flashcards do conjunto (47)
- 1What is microbiology?A branch of biology that concerns living things too small to be seen without the aid of a microscope.
- 2What are the beneficial properties of microorganisms?Decomposition
Recycling of nutrients
Absorption of gases
Basis of the food chain
For use in experimental procedures - 3What 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 - 4How are microorganisms classified?Prokaryotic: bacteria
Eukaryotic: all other living organisms - 5How are bacteria classified?Size: average 0.5-2.0um
Structure: arrangement and shape
Shapes: coccus, bacillus, coccobacillus, vibrio, spirillum, spirochete - 6What is gram positive bacteria?Thicker, peptidoglycan wall
Teichoic acids - 7What is the structure and function of flagella?Movement
- 8What is the structure and function of pilliShort protein appendages on gram negative
Smaller than flagella - 9What is the structure and function of the capsule?Protects bacteria from drying out
- 10What 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 - 11What 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 - 12What are technoic acids?Found in gram positive bacteria only
Provide rigidity
Give bacteria antigenic specificity - 13What 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 - 14What are acid fast bacteria?Have cell wall like gram positive
Also covered with thick waxy layer - 15What 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. - 16What is gram negative bacteria?Endotoxin
Extra outer membrane - 17Is gram positive or negative more sensitive to penicillin?Positive
- 18Does alcohol affect gram positive or negative more?Negative
- 19What 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 - 20What are fungi?Can grow in environments where bacteria may struggle
Grow in acidic (low pH) and cold envrionments - 21What are yeasts?Unicellular organisms
Ability to grow in two different forms
This ability affects ability to invade host tissues - 22What are protozoa?Single celled organisms (still eukaryotes)
Classified according to their abillity to move
Sarcondinia - amoebae
Mastigophora - flagellates
Ciliophora - ciliates
Sporozoa - non motile - 23What 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 - 24What 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 - 25What 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 - 26What are the effects of temperature on bacteria?Pathogenic bacteria prefer 37 degrees
Too low and they don't grow
Too high and they die - 27What 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 - 28What 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 - 29What is conjugation?Transfer of genetic material from one bacterium to another by means of a sex pill.
- 30What is the structure and replication of an endospore?Form in unfavourable conditions
Only in gram positive bacillus
Resistant structure
Survive for years - 31What is pathogenicity?The capacity to produce disease
- 32What is virulence?The degree of pathogenicity. Depends on organism
- 33What is an infectious disease?A harmful alteration of physiology or metabolism caused by a microorganism or its products.
Caused by a pathogen. - 34What is a pathogen?A microorganism that can cause disease.
- 35How can bacteria cause disease?Bacteria become established
Penetrate defenses
Invade tissues
Multiply
Produce clinical symptoms - 36What 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 - 37What 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% - 38What 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 - 39What 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 - 40What are slime layers?Secrete sticky stuff and can form multiple layers
Sticks the layer of bacteria to the surface - 41What 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. - 42What 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 - 43What 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 - 44What is bacterial haemolysis?Red blood cells damaged by toxins
- 45What 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 - 46What are toxoids?Toxins modified by heart of chemicals to remove their toxicity but retain ability to elicit an immune response.
- 47What 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
Informações
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- University Microbiology (Semester 1) FlashCards sobre Microorganisms, criado por Hannah Waters em 07-06-2016.
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- Hannah Waters
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