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144 Cards in this Set
- Front
- Back
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What are the major target sites of antibiotics? (3) |
Cell wall synthesis, protein synthesis and nucleic acid synthesis |
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What is the difference between bacteriostatic and bactericidal antibiotics? |
Bacteriostatic antibiotics inhibit growth, bactericidal antibiotics kill the cell |
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How do antibiotics such as penicillin inhibit cell wall synthesis? |
They contain beta-lactam structures which mimic the D-ala-ala binding site of transpeptidase which forms a cross links between peptidoglycan chains |
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How do some bacteria become resistant to penicillin and how is this combatted? (2) |
- They produce B lactamases that degrade the ring structure of penicillin - strains of penicillin are combined with clavulanic acid which is a beta lactamase inhibitor circumventing the organism's resistant to penicillin |
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How do antibiotics such as kanamycin and tetracycline, inhibit protein synthesis? (2) |
Bind to the 30s ribosomal subunit creating fissures in the of cell membrane leading to cell lysis. only effective against aerobic bacteria |
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How do antibiotics such as fluoroquinolone and erythromycin inhibit nucleic acid synthesis? (2) |
Erythromycin bind to 50s subunit and prevents incoming trnas from binding Fluoroquinolone bind to DNA gyrase prevent in supercoiling of DNA and inhibiting replication |
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What is an anti metabolite? |
Molecules such as sulphonamides that prevent folate synthesis |
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What are the two over all types of antibiotic resistance in bacteria? |
Natural resistance which is a lack of target structure or impermeable to the antibiotic And developed bacterial resistance which is required by the bacteria |
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What are the three mechanisms by which a bacteria develops resistance to an antibiotic? |
Enzymatic inactivation of the antibiotic, modification of the target or development of a pump that removes the antibiotic by efflux mechanism |
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What are the three main reasons why bacteria develop antibiotic resistance? |
Selection pressure of the antibiotics darwinism, transfer of resistance genes and rapid cell division |
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What are the three types of transfer of resistance genes? |
Transduction where DNA is transferred via bacteriophage transformation where naked DNA is taken from the surrounding environment, conjugation where two cells exchange DNA via plasmids |
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What is a resistome? |
A reservoir of resistance genes sometimes present in non pathogenic bacteria |
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Give an example of enzymatic inactivation resistance |
Resistance to beta-lactams in the case of penicillin occurs when beta-lactamases cleave the Beta lactam ring inactivating the antibiotic |
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Give an example of active efflux resistance mechanism |
Tetracycline resistance is an example of this, cytoplasmic membrane protein pumps out the antibiotic immediately |
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Give an example of target modification resistance |
A form of penicillin resistance involves transpeptidase having an altered shapes therefore penicillin can no longer bind and inhibit crosslinks of peptidoglycan chains |
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What are the two categories of fungus to kill insects? |
Entomophthorales = invade and kill via spores and also host specific Nematode trapping fungi (ascomyota) = forms traps when available nitrogen is low, used in biological control for nematodes |
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Describe how necrotrophs penetrate hosts using their appressaria formation (3) |
The end of the germ tube swells and anchors to the leaf surface, there is an increase in turgor pressure and the peg punches through the plant cell wall |
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What are haustoria? (3) |
Vascular like structures produced by fungi, penetrate only the cell wall and used to siphon sugars from a host |
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What are the two types of fungal plant diseases? |
Necrotrophs- invade and kill the plant quickly and then live on the remains biotroph found in living plants do not kill the host and possess Haustoria |
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Name 5 types of damage caused by plant bacterial diseases |
- Soft rots - Wilts = clogged vascular tissue - blights= rapid destruction of plant tissue - canker sores - plant tumours |
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What are 3 factors produced by pathogens to cause damage? |
Toxins = interfere with wholesale mechanisms of metabolism enzymes =used to penetrate the Host that break down molecules for assimilation growth regulators = of the growth of host a favour pathogen invasion |
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What are the seven factors of emergent / re emergence of diseases? |
Demographics news 2 cities more crowded transportation bolt processing economic development international travel microbial adaptation biological warfare and breakdown of public health measures |
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What are the three types of epidemic control measures? |
Eliminate= quarantine and isolate the source Break connection between source and host Raise level of herd immunity vaccinate |
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What is antigenic shift? |
Gene exchange between different strains Leads to major changes in virus protein coat |
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What is antigenic drift? (2) |
- Minor antigenic variation due to mutation - hemagglutinin and Neuraminidase change leading to formation of a new strain |
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What is herd immunity? |
Resistance of a population to an infection due to the immunity of the majority |
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What are the two types of epidemic? |
Common source = surprise to a peak very rapid decline propagated = slow rise and gradual decline |
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What is the difference between morbidity and mortality rate? |
Mobility rate is the number of individuals become an ill and mortality rate is relationship between death and kisses |
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Define endemic epidemic and pandemic diseases |
Endemic low levels at frequent intervals epidemic sudden increase larger than expected pandemic increase simultaneously over wide area |
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What is human papillomavirus (HPV)? (2) |
-Causes warts -sometimes oncogenic such as HPV 16 and 18 that cause cervical cancer |
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What are adenoviruses?(4) |
-Mostly non serious infections -Types 1-7 respiratory in nature -Types 8 and 9 keratoconjunctivitis -Types of 11 and 21 hemorrhagic cystitis (very serious) |
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What are paramyxoviruses? (3) |
-Measles, mumps and rubella -common childhood disease, congenital rubella can lead to blindness and mental retardation - RNA genetic material |
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What are the three types of human herpesvirus? |
Herpes Simplex Virus= HSV1: Cold sores, HSV2: genital herpes Vericella zoster virus= VZV: chickenpox and shingles |
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How do anti flu drugs such as tamiflu and relenza work? |
The block budding of cell membranes and exit of virions |
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How are influenza viruses defined? |
By hemagglutinin and Neuraminidase antigens E.g H1N1 : swine flu |
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Name the 4 main viral genuses with examples |
Enterovirus= polio hepatovirus=hepatitis A rhinovirus=common cold aphthovirus = foot and mouth |
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What are the four main methods of viral transmission? |
Inhalation ingestion inoculation: through skin or mucous membrane congenital:mother to the foetus |
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What are endotoxins? (3) |
- Cause toxic shock - lipopolysaccharide in outer leaflet of gram negative bacteria - toxin blebs off |
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How does botulinum toxin work? (2) |
- Bind glycoprotein on neurones - inhibits acetylcholine release, preventing contraction leading to paralysis |
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How do phospholipase enzymes act as cytotoxins? (2) |
-Removes the charged head group from phospholipids -destabilize the membrane and cell dies |
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What are the three types of Exotoxins? |
Enterotoxins= cholera toxin cytotoxins = phospholipase enzymes and neurotoxins= botox |
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Name the 3 stages of host Invasion for bacteria |
-Colonisation of epithelial surfaces -penetration of epithelial cells and -penetration of deeper itssues |
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What are the two ways bacteria adhere to host surfaces? |
Using peritrichous fimbrae with adhesins Or non-fimbrial adhesins on bacteria surface |
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What are the two determinants of virulence of bacteria? |
- Capsule = inhibits phagocytosis - Toxins = cause damage |
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What is virulence and how is it measured?(2) |
Degree of pathogenicity LD50 - lethal dose to kill 50% of the population Most virulent = lowest LD50 |
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What are 3 problems encountered w/ Kochs Postulates? |
- Some bacteria cannot be grown in laboratory media - Ethical issues (AIDs, Ebola) - No suitable animal model ( gonorrhea) |
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How is cause and effect of microbial infections (KOCHS POSTULATES) proven? (4) |
- organisms extracted from lesions - Grown/ cultured in lab - Organism tested to see if disease reproduced in animal - organism is then reisolated to confirm |
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Describe the stages of infection for a highly virulent pathogen e.g syphilis (3) |
- Primary lesions - secondary stage = spread to other tissues - latent phase (years) tertiary symptoms develop ( insanity and death) |
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How do termites solve the problem of low nitrogen in wood? |
They have Nitrgoen fixing spirochetes in their intestines that provide 60% of their nitrogen |
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What are tremorgens in relation to ruminants? (3) |
- Chemicals produced by fungi - Excite/inhibit smooth muscle, reducing rumen function - Can also effect skeletal muscle ( "ryegrass staggers") |
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What is lichen? (2) |
- Association of fungus + algae/cyanobacteria - Algae provides sugars, fungus protects against dessication |
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What is the difference between hind gut fermenter + rumen fermenters? |
Hind gut = Extension of lower small intestine, After stomach, first mech to evolve, poor efficient Rumen = 4 Chambered stomach, Before stomach, More efficient |
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Describe how biofilm forms on catheters (3)
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- S. epidermidis cells attach to catheter - Plasma proteins coat catheter ( Conditional film) - bacteria replicate forming antibiotic resistant biofilm |
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What are opportunistic pathogens? |
Pathogens/bacteria that do not usually cause disease and are naturally commensal |
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What are the 3 benefits of microbiota? |
- Synthesise and excrete vitamins ( K+ B12) - prevent colonisation by pathogens ( compete w/ them) - Antagonise other harmful bacteria |
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How is T-DNA exploited for genetic engineering? (2) |
- Both hormone genes and opine gene removed - replaced w/ desired gene between left and right border will be transferred |
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What is the purpose of agrobacteria integrating its T-DNA into the host plant cell? (2) |
- T-DNA containing genes for auxin, cytokynin, + opines ( AA for bacteria) - These encourage proliferation ( tumour formation) to develop disease |
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Describe the plant defence mechanism in response to agrobacterium infection ( 3) |
- Detects flagella - Causes production of Vip1, prevents T-DAN import - Bacterial VirF is used to degrade Vip1 |
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What happens during initiation of agrobacterium infection? (2) |
- Vir A/G detects acetosygringone from wound site - Branch structure forms between host and bacteria to exchange molecules |
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Name the 4 steps of agrobacterium infection |
- Chemotaxis to wound - Initiation - Integration of T-DNA - Post- integration tumour formation |
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What is crown gall disease?(2) |
- Cause by naturally occuring soil bacteria - affects near base of shoot |
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What are the pros (3) + cons (2) with anaerobic digestion? |
Pros = Biogas, Free fertiliser, low odour and pathogen free Cons = Methanogens ( long doubling time), Cause increase in hydrogen gas, acetogens formed |
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What are anaerobic digesters? (3) |
- Used treat sludge - Reduces organic matter by 50% Broken down to CH3, CO2, and H2O |
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How does the activated sludge process differ from percalating filtration? (4) |
- Microbes not attracted to surface - 10x faster - Higher running costs - More sensitive to composition of incoming water |
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How does percalating filtration treatment work? (3) |
- Microbes for biofilm on surface - Microbes in top 0.5 M oxidise organic compounds - below 0.5 oxidise NH4 -> NO3 |
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How is waste concentration measured? by law must not exceed? |
Biological Oxygen Demand (BOD) Amount of oxygen consumed by bacteria in the dark over a set time Must not exceed 20mgL^(-1) |
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What are the 3 objectives of waster water treatment? |
- Reduce suspended solids - Reduce pathogenic microbes - RemoveNH4 ( Converted to NO3) |
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What problems arise from untreated waste/sewage? (4) |
- Reduction in dissolved Oxygen -> death of aquatic life - Solids cause silting ( blockage) in rivers - Toxic - Spread of pathogens |
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What are the problems of agricultural monoculture? |
Mainly group susceptibility to the same disease |
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How is Bt toxin expressed in plants?(3 ) and why is this method of delivery used? |
- Bacterial gene placed in front of promoter - Transform the plant - Larvae feed and ingest - This method of delivery is most efficient |
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4 Advantages and 4 Disadvantages of trangenic soybeans? |
Advantages = Pre or psot emergence, 1 Spray, 3x less toxic that others, COST Disadvantages = Resistance transferred, some toxicity, reliance on herbicide, premium to monsanto |
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Describe the dual strategy for glycophosate resistance (2) |
- Glycophosate oxidase breaks down glycophosate to glycine - Resistance gene (CP4) allows shikimate pathway to work |
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How are plants made resistant to glycophosate? (3) |
- Mutant AroA gene infront of strong promoter - Plant version of gene still inhibited but not mutant - Resistant crop grows, all weeds killed |
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What are the advantages of glycophosate? (4) |
- Broad based - Resistance is rare - Does not persist in environment - No toxicity to humans or animals ( no shikimate pathway) |
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What is Glycophosate and how does it work? |
- powerful herbicide - Shikimate pathway ( inhibits EPSP synthase) |
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What are the problems w/ convenional herbicides? (3) |
- Hard to distinguish, similar plant species - Poor environmental properties = persistence, non target toxicity - Resistance |
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What are the advantages of Bt corn? (3) |
- More effective pest control - Low ratees of disease ( no wounds for infection) - higher yields |
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What is ergot poisoning? (3) |
- Toxins in ergot - Joint pain, hallucenations, seizures, gangrene - Salem witch trials |
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What are myotoxins? ( example, aflatoxins) (3) |
- Toxic fungal metabolites - Highly toxic and carcinogenic - Affects man and livestock "turkey X disease2 |
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What is listeriosis? (2) |
- Affects fresh, raw veg, unpasteurised milk, cheese and raw meat - Grows at 4 degrees |
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Name the 4 high risk groups for foodborne disease (listeria) |
- Pregnant women - Infants - Elderly - immunosuppressed |
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What are the major reasons for foodborne disease? (4) |
- mass production of food - mass processing - New strains/ antibiotic resistance - mass transport |
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What is phyate and phytase? (3) |
- In animal feed, inorganic phosphate in phytate - cannot be degraded by monogastric animals - Microbial phytase added to feed to release phosphate |
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What is the problem with non-starch polysaccharides in the animal feed industry? (2) |
- High arabinoglucans, increased viscosity reducing absorption - combatted by including beta glucanase in feed |
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What 2 types of molecules contribute to flavour in alcoholic drinks and how? |
Esters = Fruity character Fusels alcohols = strong alcoholic flavours |
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What is similar about how camembert and roquefort cheese is made and what's the difference? |
Both produced using mould (fungi) Camembert = fungi grows on surface Roquefort = fungi grows throughout cheese |
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What is rennet? (Cheese production) (3) |
- Works best under acidic conditions - Extracted from calf stomachs - 90% of all cheese produced using Rennet |
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Describe an example of animal-bacteria symbiosis (2) |
- vibriofisheri (bioluminescent bacterium) - used as a lure or a disguise ( hawaiian squid) |
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What is dutch elm disease? (2) |
- Caused by fungus - Plant attempts to prevent fungus spreading ultimately ends up blocking its own xylem and pant dies |
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Describe dependent relationship between leafcutting ants, fungus and streptomycetes (3) |
- Ants tend the fungal garden - Hyphae sell and are eaten by ants - Streptomycetes produce antibiotics |
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What are the adaptations of psychrophiles? (3) |
- semi-fluid membranes ( unsat. fatty acids) - Antifreeze molecules ( only eukaryotes) - Altered proteins, more alpha helices and increase flexibility |
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What are the adaptations of hyperthermophiles? (2) |
- no fatty acids in membranes - Lipid monolayer NOT bilayer made of 2 phytane molecules (C40) |
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What are the adaptations of thermophiles? (2) |
- Semi-fluid membranes (sat. fatty acids) - Altered proteins= heat resistant conformations |
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Describe the method of autoclaving (3) |
- 121 degrees Celsius - 20 mins -138kPa kills all known microbes |
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3 General Properties of viruses |
- Extracellular state (virions) - Surrounded by protein - metabolically inert |
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3 processes that occur once a virus has entered a cell? |
- viral replication - Virus redirects host machinery - Virions produced ( late infection ) |
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Describe the structure of a virion (2) |
- Nucleic acid surrounded by protein coat ( capsid) -Capsid made of capsomers ( made of 1 protein or several) |
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Describe helical symmetry in viruses (2) |
- length determined by length of RNA - Width determined by packing subunits |
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Described icosahedral symmetry in viruses (3) |
- 20 faces - 12 pentons - 5-3-2 rotational symmetry |
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Describe the steps of the virus replication cycle (6) |
1) attaches to receptors 2) pentration ( endocytosis into cell) 3) uncoating (nucleic acid exposure) 4) NA synthesis and protein synthesis 5) assembly of subunits/packaging 6) released of mature virions |
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How do virions exit the host cell? |
Budding from the membrane |
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name the 3 basic cell structures of fungi |
- Unicellular - Dimorphic - Filamentous |
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What is Ascomycota fungi? (3) |
- Airborne spores ( asexual spores) "Conidiospores" - 8 sexual spores ( ascospores) in an ascus - Plant pathogen ( food spoilage) |
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What is Chytridomycota fungi? (3) |
-Aquatic fungi - Asexual + sexual flagellated spores - Most primitive fungi |
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What is zygomycota fungi? (2) |
- terrestrial - Asexual, non-motile spore ( Zygospore) |
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What is basidomycota fungi? (4) |
- Mushrooms and toadstools - 4 sexual basidospores -gills/ores of mushroom - form mycorrhizal associations w/ trees |
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Characteristics of the right chronometer concerning phylogeny? (3) |
- Molecule should be universally distributed - DNA sequences of molecule should evolve slowly ( to reflect evolutionary distance) - ribosomal DNA |
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Where do hetertrophs and autotrophs get their carbon? |
Autotrophs = CO2 fixation heterotrophs = organic molecules |
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What are methanogens? (2) |
- Archaea = strict anaerobes - CO2 as electron acceptor producing CH4 |
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Where do; Chemoorganotrophs, chemolithotrophs, phototrophs obtain their energy? |
Chemoorganotrophs = organic chemicals Chemolithotrophs = Inorganic chemicals Phototrophs = light |
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Describe a bacteria that oxidises iron (2) |
- Thiobacillus ferroxidans - large amounts of iron needed |
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Describe anoxygenic photosynthesis (3) |
- H2/ H2S as electron donor - for oxidative phosphorylation - Sulphur formed |
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Name the 4 temperature classifications and associated temperatures |
psychophiles = <15 degrees Celsius mesophiles = 15-45 degrees Thermophiles = 45- 80 degrees Hyperthermophiles = 80-100 degrees |
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Why does a lag phase occur during bacterial growth? (4) |
- Cells may be old - Depleted ATP/ Ribosomes - Injured cells - Adjusting to new medium |
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What is the FesZ ring concerning bacteria? |
Protein filament ring that contracts to break the cell walls allowing binary fission |
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Define mean doubling time |
Time for a population of bacteria to double |
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3 Features needed for bacteria growth? |
- carbon source - nitrogen source - growth factors ( Vitamins, nucleotides etc.) |
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4 Properties of flagella |
- helical and rigid - 20 nm diameter - Subunit ( flagellin) - biological rotary motor at base |
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4 properties of fimbriae |
- pertrichous - Straight or flexible - Carry adhesins to attach to receptors - Function = Protect against force, adhere to surfaces, obtain nutrients |
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name the 2 type of flagella |
Polar = single (spins helically) Peritrichous = several flagella |
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Name the 4 essential structures and 3 optimal structures of bacteria |
Essential = membrane, wall, nuceloid, ribosomes Optional = Flagella, fimbriae (pili), capsule |
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What is the difference between gram positive and gram negative bacteria? |
Positive = thick cell wall, No outer membrane, homogenous ( single layer) Negative = Thin cell wall, present outer membrane, Heterogenous cell wall ( multiple layers) |
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Describe process of gram stain (4 ) |
- Stain w/ crystal violet - Stain w/ iodine - Acetone - Safranin |
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What colour do gram positive and negative bacteria stain? |
Positive = PURPLE Negative = PINK/RED |
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Name the 7 shapes of bacteria |
1) Coccus ( cone ) 2) Rods 3) SPiral 4) Spirochetes 5) square 6) Star 7) huge |
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Degradation of lignin by fungi leaves wood what shade? |
PALE ( only cellulose left) |
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What is denitrification? |
Inorganic nitrogen is converted to N2 gas under anaerobic conditions |
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Degradation of cellulose by fungi leaves wood what colour/shade? |
BROWN ( only lignin left) |
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2 Most common food industry uses for microbes |
Cheese = Rennet ( Chymosin) Ale/lager = S. Cerevisiae/ s.carlsbergenesis |
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What is ammonification? (2) |
- Decomp of N to release NH3 - Anaerobically/aerobically by bacteria and aerobically by fungi |
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What is nitrification? (4) |
- nitrobacter + nitrosommonas - Conversion of NH3 -> NO3 - Aerobic soils - Can lead to eutrophication (Combatted with inhibitors) |
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What are bacteroids? (2) |
- Nitrogen fixing cells that diffrentiate from rhizobia - Occur inside nodules |
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What are the 2 main typea of mycorrhizal associations? |
Ectomycorrhiza = mainly basidomycetes Endomycorrhiza = manily zygomycetes and grasses |
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What is the difference between endomycorrhiza and ectomycorrhiza? |
in ecto the hyphae grow between plant cells and in endo hyphae penetrate the cells |
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Unstable infection by mycorrhizal fungi can have what 3 outcomes? |
- Germination and mycorrhiza formation - Parasitisation = plant dies - Rejection of fungi = Plant dies |
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What are pelatons in relation to mycorrhizal associations of fungi with species of orchids? (3) |
- Coils of hyphae - increases the SA between the two - Short life span ( ultimately digested by orchid) |
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What is syntrophy? |
Process by which a second organism lives off the products of another organism |
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Name 3 members of Enterobacteriaceae |
E.coli Shigella Salmonella |
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How many species of leguminous plants that symbiontically associate with rhizobia are there? |
15,000 |
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Describe the anoxygenic photosynthesis by purple/green sulphur bacteria? (2) |
- Cyclic electron transfer forms ATP - Non cyclic forms NADH |
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Name a feature shared by eubacteria and archaea? |
Linear Chromosomes |
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Where in the human body is the largest amount of bacteria? |
The colon ( large intestine) |
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Under what conditions is bt toxin soluble? |
high pH; above 9.5 ( insoluble in normal conditions) |
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What type of microorganisms are present in the stomach of ruminant animals? (4) |
Fungi, Archaea,bacteria and protozoa |
