Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
241 Cards in this Set
- Front
- Back
|
What is meant by "membranes are ubiquitous" and why are they? |
Membranes are essential for life - ALL organisms have them |
|
|
What are membranes essential |
Compartmentalise internal and external environments |
|
|
What are the functions of membranes |
1. Separate and isolate internal environments 2. Energy production 3. Signalling 4. Intelligent barrier (transport) |
|
|
What are membranes made from? |
Phospholipid bilayer |
|
|
How do membranes self form? |
1.Phospholipids are polar - hydrophobic and hydrophilic ends 2. Hydrophobic ends form inside bilayer 3. Hydrophilic ends form outside bilayer 4. Most energetically stable way to reduce contact of hydrophobic ends to aqueous environment. |
|
|
What role do membranes play in energy generation |
They provide a semi-permeable barrier Create a concentration gradient of ions As ions diffuse through channels drives synthesis of ATP from ADP |
|
|
What is the lipid transition temperature |
The temperature a particular lipid changes state from liquid to solid. |
|
|
What can affect the lipid transition temperature? |
Fatty acid tail length Saturation |
|
|
What role does saturation play in lipid transition temperature? |
Unsat fats = C-C double bond Creates kinks in tails Cannot pack as tightly Weaker interactions Liquid at lower temperatures |
|
|
What role does fatty acid tail length play in lipid transition temperature? |
The longer the fatty acid tail the more van der Waals interactions between each lipid. Greater temperature is required to separate Solid at higher temperatures |
|
|
What implications does habitat have on the likely lipid type found in the organism that resides there? |
In cold environments organisms are likely to have membranes which are short tailed and unsaturated.
|
|
|
What is the only species of bacteria not to have a cell wall? |
Mycoplasma |
|
|
What is the function of a cell wall? |
To prevent cells lysing from their own internal pressure Mechanical support |
|
|
Is creating an antibiotic to target a cell wall good or bad. Why? |
Good, as animal cells don't have cell walls will not harm host. |
|
|
What is characteristic of a gram positive bacteria? |
1. Thick peptidoglycan cell wall 2. Teichoic and Lipoteichoic acids throughout wall 3. Cell membrane beneath |
|
|
What is characteristic of gram negative bacteria? |
1. Thin peptidoglycan cell wall 2. Lipopolysaccharides 3. Outer and inner membranes |
|
|
Once stained with gram stain, what colour are gram positive bacteria? |
Purple |
|
|
Once stained with gram stain, what colour are gram negative bacteria? |
Pink/Red |
|
|
What is the gram staining process? |
1. Crystal violet dye - penetrates cell wall of both bacteria 2. Iodine wash - forms large complexes with crystal violet 3. Alcohol decolourising wash - washes CV complex from beneath thin peptidoglycan wall in gram negative 4. Counterstain - safranin turns decolourised cells pink |
|
|
What is the basic structure of peptidoglycan |
Alternating Nag-Nam pattern linked by beta(1,4)glycocidic bonds Cross linked by peptide bridges |
|
|
Who discovered both lysozyme and penicillin |
Fleming |
|
|
What bond does lysozyme target? |
Beta (1,4) glycocidic bond |
|
|
What does Nag stand for? |
N-acetylglucosamine |
|
|
What does Nam stand for? |
N-acetylmuramic acid |
|
|
Do the peptide cross links in peptidoglycan run Nag>Nag, Nam>Nam or Nag>Nam |
Nam>Nam |
|
|
Why do both penicillin and lysozyme have a greater effect on gram positive bacteria? |
Greater amount of peptidoglycan in gram +ve |
|
|
Which enzyme does penicillin target? |
Transpeptidases |
|
|
What is the function of the enzyme that penicillin targets |
Transpeptidases build the interpeptide bridge in peptidoglycan |
|
|
What is an endotoxin? Give an example |
Endotoxin is released by bacteria and elicits a strong immunological response. Eg. Lipopolysaccharide |
|
|
What syndrome is the release of LPS associated with? |
Septicemic shock and Toxic Shock Syndrome |
|
|
What is an S layer? |
A mono-molecular surface layer in bacteria formed from proteins |
|
|
What are capsules composed of |
polysaccharides |
|
|
Are capsules more common in gram +ve or gram -ve bacteria? |
Gram negative |
|
|
Name 2 differences between archaea and bacteria? |
1. Archaea cell walls do not contain peptidoglycan 2. Archaea membranes have a different composition |
|
|
What are 4 differences between the cell membranes of bacteria and archaea? |
1. Chirality of glycerol 2. Ether linkage 3. Branched fatty acid chains 4. Continuous tails |
|
|
What is different between the chirality of the glycerol in archaic membranes? |
In EuK and bacteria D-glycerol In Archaea L-Glycerol
|
|
|
Do archaea or bacteria have Ester linked phospholipids? |
Ester = EuK and bacteria Ether = Archaea |
|
|
What is the name of the branching of the side chains in the archaic fatty acids within the membrane? |
Isoprenoid chains |
|
|
Why is it said that archaic membranes are monolayers? |
The fatty acid tails join and are continuous between the two layers. |
|
|
What is a fungi membrane made of? |
Ergosterol |
|
|
What is a fungal cell wall made of? |
Chitin |
|
|
What is chitin made of? |
Nag repeating units bonded beta(1,4)glycocidic bond |
|
|
Imidazoles and triazoles are antifungal drugs which target what? |
ergosterol synthesis |
|
|
Polyenes are antifungal drugs that target what? |
ergosterol directly, causing leaks |
|
|
Why is it very difficult to treat unicellular parasites such as protozoan parasites? |
Eukaryotic, so have same external cell features as host. Drugs that harm parasite will usually also harm host. |
|
|
What is the term for a round shaped bacteria?
|
Cocci |
|
|
What is the term for a elongated oval/oblong shaped bacteria?
|
rod or bacili
|
|
|
What is the term for a chain of round bacteria?
|
streptococci |
|
|
What is the term for a chain of rod shaped bacteria? |
streptobacili |
|
|
What is the term for spiral shaped bacteria? |
Spirochete |
|
|
What is the term for clusters of round shaped bacteria? |
Staphylococcus |
|
|
What is the term for a pair of round bacteria?
|
Diplococci |
|
|
What is the term for a pair of rod shaped bacteria? |
Diplobacili
|
|
|
What is the term for a chain of rod shaped bacteria, with long ends touching? |
Pallisades |
|
|
What is the term for four round bacteria in a square configuration? |
tetrad |
|
|
What is the term for 8 round bacteria in a cube formation? |
sarcina |
|
|
What is the term for curved bacteria? |
Vibrios |
|
|
What are the different forms of bacterial colonies?
|
circular, irregular, filamentous and rhizoid |
|
|
What are the different forms of elevations of bacterial colonies?
|
raised convex flat umbonate crateriform |
|
|
{ Which type of bacterial colony elevation looks like this symbol (with a bobble in the middle)?
|
umbonate
|
|
|
What are the 5 forms of margins of bacterial colony?
|
undulate filiform curled lobate |
|
|
What are 3 other factors of diversity within bacterial populations |
odd shapes complex life cycles |
|
|
Which bacteria has the most complicated life cycle studied? |
Gliding Myxobacteria
|
|
|
What is the name for filaments on the surface of bacteria that aid attachment or adhesion to each other or other surfaces? |
Fimbriae or common pili |
|
|
What is the name for filaments on the surface of bacteria that enables horizontal gene transfer |
F Pili |
|
|
What is the name for filaments on the surface of bacteria that enables motility in many bacteria?? |
Flagellum
|
|
|
What is the name of the type of bacteria that has a single flagellum on one end of the cell? |
monotrichous polar |
|
|
What is the name of the type of bacteria that has many flagella at one end of the cell? |
lophotrichous polar |
|
|
What is the name of the type of bacteria that has one flagellum at either end of the cell? |
Amphitrichous polar |
|
|
What is the name of the type of bacteria that has many flagella all over the surface of the cell? |
peritrichous |
|
|
Flagella are linked to the sensory system to enable bacteria to do what? |
Phototaxis and chemotaxis. |
|
|
What is the name of the structure that enables bacteria to transfer electrons relatively long distances to other cells or an external substrate? |
Nanowires |
|
|
What is the process of creating bacterial endospores?
|
2. Asymetric cell division 3. Septum formation to separate prespore and mother cell 4. Engulfment of prespore by mother cell 5. Cortex of spore forms 6. Coat synthesis 7. Maturation and lysis |
|
|
What is the cortex of the spore made of? |
Layers of peptidoglycan |
|
|
What does the core of a spore contain and what is the function of these chemicals?
|
Dehydrates spore stabilizes DNA |
|
|
What is the spore coat made of
|
Spore proteins |
|
|
What are SASPs |
small acid soluble proteins
|
|
|
What is the purpose of SASPs
|
bind to DNA to protect from UV and heat |
|
|
Why do some bacteria produce endospores? |
To ensure survival of a bacterium through environmental stress |
|
|
What is filamentation
|
cell elongation but no division many chromosomes per cell response to stresses |
|
|
What are the 4 types of protozoan morphology |
Sporozoa Flagellates Amoebae Ciliates |
|
|
What differentiates sporozoa from other protozoans?
|
intracellular |
|
|
What differentiates flagellates from other protozoans?
|
movements by flagella
|
|
|
What differentiates amoebae from other protozoans?
|
Movement through extending pseudopodia No fixed shape |
|
|
What differentiates ciliates from other protozoans?
|
move by beating cilia
|
|
|
Are EuK more closely related to ProK or Archaea?
|
Archaea |
|
|
What are similarities between archaea and EuK
|
-membrane remodelling -ubiquitin modification -endocytosis + phagocytosis genes and several metabolic pathways that closely related the EuK |
|
|
What are the only groups of eukaryotes that have evolved embryogenesis |
animalia |
|
|
Roughly how many phyla in EuK
|
30-40 |
|
|
What are the selective advantages of eukaryotic cells |
compartmentalization by internal membranes results in - raised metabolic concentration - creation of different environments - assist with metabolic control - accommodation of pH and Potential gradients |
|
|
What is a raise in metabolic concentration beneficial for a eukaryotic cell?
|
- lower substrate affinities required |
|
|
Why is the accommodation of a gradient, either potential or pH, within a Eukaryotic cell a benefit? |
essential for oxidative phosphorylation - respiration |
|
|
What is the proof that mitochondria are endosymbionts, evolved from bacteria? |
2. circular DNA 3. encoding genes in nucleus from bacterial origin |
|
|
What is the different between mitochondrial ribosomes, eukaryotic ribosomes and prokaryotic ribosomes? |
ProK + mitochondria = 70S (50S and 30S subunits) |
|
|
How do mitochondria split within a cell? |
Endoplasmic reticulum |
|
|
How does a zygote only have maternal mtDNA in?
|
1. inner membrane disrupted causing a disruption to the inner membrane potential 2. mtDNA exposed and degraded 3. lysosome fuses and clears up debris |
|
|
Name 2 further endosymbionts, excluding the mitochondria |
hydrogenosome |
|
|
Is the internal structure of the chloroplast within plant cells identical to it's bacterial counterpart?
|
|
|
|
What is a feature of chloroplasts that is characteristic of a prokaryotic feature
|
lipid bilayer similar to prokaryotic membrane. |
|
|
What does a hydrogenosome do and where is it found?
|
found in some anaerobic ciliates, trichomonads and fungi. |
|
|
What is a drug that targets hydrogenosomes?
|
metronidazole |
|
|
What are the possible origins of hydrogenosomes? |
or mitochondria which have lost mitochondrial features (notably it's genome) |
|
|
What are the 3 types of protest cell motility |
flagellate cilliate |
|
|
Name two types of amoeboid protest and the diseases that they cause. |
Entamoeba gingivalis - gum disease |
|
|
What is the structure of a flagella in protists? |
9 outer pairs of microtubules central pair called axoneme tubulin protein |
|
|
What is the associated protein of flagella in protists? What is it's function |
ATP-ase |
|
|
What is the structure of bacterial flagella
? |
helical array of flagellin
|
|
|
How does the evolutionary history of proctist and bacterial flagella differ?
|
proctist flagella originates from cytoskeleton bacterial flagella originates from secretory system |
|
|
Name the group of flagellate proctists that include the cause for African sleeping sickness. Name the particular organism in this example. |
Trypanosoma bruceii |
|
|
What kinetoplastids cause kissing bug or Chagas disease?
|
trypanosome cruzi |
|
|
What is important biologically about the gut symbionts of termites
|
essential for wood digestion have own symbiont methanogenic nitrogen fixers allow to get nutrients from wood |
|
|
Name a type of protist cilliate |
Paramecium
|
|
|
What are ruminants? |
hydrolyse cellulose |
|
|
What are the rumants equivalents in horses and rabbits? |
Caecants |
|
|
What are apicomplexa |
infect cell without entering, but by using special organelle called Rhoptry out of their apical end. Include the malarias |
|
|
What is the name of the parasite that only can come from cats. IgM presence for this disease indicates fetal harm but what other antibody will mean that the fetus is safe. Why is this? |
IgM means recent infection IgG means old infection, and mother's immune system has surpressed it. |
|
|
toxoplasma gondii can cause what ailment in new borns?
|
hydroencephalus |
|
|
What are slime moulds
|
amoebozoa protists
|
|
|
What are the two types of slime mould
|
cellular slime mould |
|
|
What is the difference between the two types of slime mould |
Cellular = most of the time unicellular but assemble into a cluster to act as one large organism upon secretion of cAMP |
|
|
What characteristic do cells of slime moulds exhibit to ensure that their genetic material becomes part of spore? What genes are involved? |
tgrC1 and tgrB1 |
|
|
According to Herodotus, Foraminifera form the rock of which famous structure today?
|
Pyramids |
|
|
What keeps plankton populations in check? Give an example
|
Viruses - coccolithovirus |
|
|
What does a coccolithovirus produce to keep the cell that it's infected from dying. This enables to virus to replicate for a prolonged period/
|
prevents apoptosis |
|
|
What are diatoms |
major group of eukaryotic algae encased in cell wall called frustules or tests |
|
|
Why are diatoms called diatoms
|
|
|
|
What makes a frustule?
|
polymerized silicic acid monomers |
|
|
What makes dynamite? |
nitroglycerine and diatomaceous earth |
|
|
What are dinoflagellates? |
symbiont of reef building coral |
|
|
What interesting intracellular structure has been found in dinoflagellates?
|
lens |
|
|
What two organisms make up a lichen? |
fungi + photosynthetic partner (either cyanobacteria or green algae) |
|
|
How do lichens feed? |
+ extract minerals from rocks, dust + animal excreta |
|
|
What compound protects lichens from sunlight and grazing animals?
|
Usnic acid
|
|
|
What are the 4 types of fungi
|
mould mushrooms lichens |
|
|
How do fungi feed?
|
degrade proteins and polysaccharides reabsorb micronutrients |
|
|
What can be a replacement for chitin in a fungal cell wall |
galactosans chitosans |
|
|
What are small individual structures of fungi called?
|
hyphae |
|
|
What are masses of filamentous fungal cells called? |
mycelium |
|
|
What is the fruiting body of a fungi called? |
conidia |
|
|
What are mycorrhizae
|
mutualistic association with plant roots |
|
|
What are the two types of mycorrhizae and how do they differ? |
endomycorrhizae - mycelium embedded within root |
|
|
What are the benefits for each party of a mycorrhizae |
allows more efficient nutrient uptake fungi = carbon from root secretions and inorganic materials from the soil |
|
|
What is the largest organism on earth
|
honey fungus = 9km squared. |
|
|
What are the arguments for viruses being alive or not?
|
- nucleic acid genetic material - can replicate NO - host cell required for replication - need to exploit host cells metabolic processes |
|
|
In comparison to bacteria, roughly how small are viruses
|
10 x smaller |
|
|
In terms of numbers of genes, how small is a virus? |
can be as small as 5 genes |
|
|
What are the three main components of a virus
|
protein subunits envelope ( plasma membrane - not essential) |
|
|
All viruses (or their nucleocapsids at least) are symmetrical - True or False and explain? |
helical or icosahedral symmetry |
|
|
What are the two main shapes of virus? What are their underlying symmetry
|
Rod (helical) |
|
|
Give an example of a rod virus
|
tobacco mosaic virus |
|
|
Give an example of a spherical virus |
human papilloma virus |
|
|
What is a complex virus, give an example and describe it's structure |
i.e. bacteriophage T4 icosahedral head collar helical tail end plate many tail fibres |
|
|
How are viruses classified? What is the name of the system
|
double stranded DNA single stranded DNA double stranded RNA single stranded RNA RNA -> DNA changing called Baltimore classification |
|
|
What is the most common virus type |
double or single stranded RNA |
|
|
How is the viral envelope acquired? |
as budding from the surface of cells, the lipid bilayer envelopes the virus |
|
|
Give 2 examples of different enzymes present on the virion of 2 viruses/.
|
neuraminidase on influenza - required for release from infected cell |
|
|
What is a virion
|
the extracellular form of the virus |
|
|
What enzymes are always carried by RNA viruses? |
replicases |
|
|
What enzyme in particular is always carried by retroviruses?
|
reverse transcriptase - change RNA to DNA |
|
|
What is the one cellular process that ALL viruses need from their host |
protein translation on ribosomes. |
|
|
WHat are the 5 stages of virus replication |
2 penetration 3 synthesis 4 assembly 5 release or egress |
|
|
How do viruses attach to animal cells and how does this allow them to gain entry? |
signals cell to endocytose or for their membranes to fuse |
|
|
What about the attachment stage of viral replication promotes target cell specificity? |
viruses only bind to specific receptors on cells |
|
|
What is the penetration stage of viral replication |
after the membrane of the virus and cell are fused the RNA contents of the virus are released in to the cytoplasm of the cell. |
|
|
What is the order of events in the synthesis stage of viral replication |
THEN genome is replication |
|
|
What is the assembly stage of viral replication
|
Virus capsids self assemble |
|
|
What are the three methods of egress for a virus after it has been replication within a cell |
2. release following lysis 3. release following cell death |
|
|
Name three types of subviral entities |
2. viroids 3. prions |
|
|
Give an example of a helper or defective virus |
phage P4 of E. Coli doesn't encode capsid protein, requires P2 to also infect cell and provide a capsid. |
|
|
What is a viroid?
|
cause disease no protein coat no protein encoding genes small circular RNA molecule stable in+outside of cells due to structure |
|
|
What is a prion
|
no nucleic acid material cause mad cow disease and CJD |
|
|
Define pathogen |
microorganism capable of causing disease |
|
|
Define opportunistic pathogen |
initiates disease in compromised hosts |
|
|
Give an example of an opportunistic pathogen |
Candida albicans (thrush) |
|
|
Define primary pathogen |
Pathogens that cause disease in healthy individuals |
|
|
Define Virulence |
quantitative term used to indicate the degree of pathogenicity |
|
|
Define Virulence Factor |
Properties of a microorganism that determines it's virulence |
|
|
What is virulence measured in? |
LD50 Median lethal dose dose required to kill half of a population over a given duration |
|
|
What is more toxic, a smaller or larger LD |
Smaller LD = more toxic |
|
|
A larger virulence will be associated with a smaller or larger LD |
smaller LD |
|
|
What 4 things must a pathogen do to cause disease? |
enter host metabolise + multiply in tissue resist defenses cause damage |
|
|
What are the key virulence factors of Salmonella |
Type 1 fimbriae Flagellum Vi Capsule antigen Cytotoxin Enterotoxin Injectosome Endotoxin Antiphagocytic proteins |
|
|
Why is Type 1 fimbriae a virulence factor? |
aids in attachment/adhesion |
|
|
Why is a Flagellum a virulence factor? |
aids in adherence motility reduction in ability to be phagocytosed |
|
|
Why is a Vi capsule antigen a virulence factor? |
inhibits complement binding |
|
|
Why is a cytotoxin a virulence factor? |
inhibit host cell protein synthesis can cause calcium influx into host leads to adherence |
|
|
Why is enterotoxin a virulence factor? |
causes diarrhea |
|
|
Where does most infection begin in the body? |
mucus membranes |
|
|
Adhesion of a bacteria to host is tissue specific, but not host specific, TRUE OR FALSE. |
FALSE adherence is both tissue and host specific |
|
|
What are bacterial adhesins? |
bacterial subunit proteins located on fimbriae tip interact with host receptor for adherence. |
|
|
What type of receptors do adhesins usually bind to? |
glycoproteins or glycolipid receptors |
|
|
What structure of N Gonorrhoeae plays a key role in attachment to the urogenital tract? |
Pili |
|
|
What types of receptors are in the bladder and kidneys and are targeted in a urogenital infection |
specific sugar motifs |
|
|
What types of pili are usually involved in urogenital tract infections in the kidney and bladder respectively? |
Kidney = P Pili Bladder = type 1 pili |
|
|
Aside from fimbriae, what is the other main method of attachment for a pathogen and the host. |
non-covalent attachement through secreted polysaccharide, proteins or protein carbohydrate mixture. |
|
|
What are the two types of polymer coats that allow non-covalent attachment of pathogens |
slime layers = loose network capsule coats = well defined layers |
|
|
Name 7 types of enzymes that are used by pathogens to aid establishment of disease |
Hyaluronidase Collagenase Lecithenase Streptokinase Coagulase Haemolysins Leucocidins |
|
|
What does hyaluronidase do? |
- hydrolyses hyaluronic acid (tissue cement) |
|
|
What does collagenase do? |
break down collagen network supporting the tissues |
|
|
What does lecithenase do? |
lyses cells, especially RBC/erythrocytes |
|
|
What does coagulase do? |
promotes fibrin clotting |
|
|
What does streptokinase do? |
fibrinolytic - breaks down fibrin clots |
|
|
What do haemolysins do? |
lyse erythrocytes alpha and beta |
|
|
What do leucocidins do? |
lyse leukocytes |
|
|
What are the two main families of toxin? |
Endotoxin and Exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "proteins excreted by gram + or gram - bacterial" |
exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "Specific mode of action" |
Exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "toxoid remains immunogenic" |
exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "Causes general symptoms" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "pyrogenic" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "heat labile" |
exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin?
|
exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "Relatively poor immunogen" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "treatment with formaldehyde destroys toxicity but leaves toxoid" |
exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "Neurotoxins and enterotoxins belong to this family" |
exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "stimulates the production of antitoxins (neutralising antibodies)" |
exotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "lipopolysaccharide complexes" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "produced by the lysing of the bacteria" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "from gram negative bacteria" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "extremely heat stable" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "Fever, diarrhoea and vomiting are key symptoms" |
endotoxin |
|
|
Is the following a description of an endotoxin or an exotoxin? "Immune response generated not sufficient to neutralise toxin" |
endotoxin |
|
|
What are the 3 categories of exotoxin? |
Cytolytic AB toxins Superantigens |
|
|
What are cytolytic exotoxins |
use enzymes to attack host cell constituents |
|
|
What are AB exotoxins |
A and B are two covalently attached subunit proteins B binds to surface receptor A then allowed transfer into cell to cause damage |
|
|
What are superantigens |
stimulate extremely large immune response - excessive inflammatory reaction |
|
|
Give 3 examples of AB toxins? |
Diptheria Botulinum Tetanus |
|
|
Give an example of a cytotoxin |
Cholera |
|
|
What bacteria produces diptheria |
corynebacterium diptheriae |
|
|
What bacteria produces botulinum |
clostidium botulinum |
|
|
what bacteria produces tetanus |
clostidium tetani |
|
|
What bacteria produces cholera |
vibrio cholera |
|
|
Which enzyme does cholera use for host cell damage |
pneumolysin |
|
|
How does diptheria cause illness? |
B subunit of diptheria toxin binds to cell receptor A subunit cleaved and internalised A catalyses ADP-ribosylation of EF-2 (elongation factor 2) Modified EF-2 cannot aid transfer of amino acids to growing peptide Protein synthesis halts |
|
|
How does botulinum toxin cause illness |
Prevents acetylcholine leaving synapse at motor end plate Muscles cannot be innervated for contraction Flaccid paralysis |
|
|
What is the LD50 of Botox in mice. What is the implication of this? |
25 pictograms Very tiny amount (25 millionths of a gram) Very large toxicity |
|
|
How does tetanus toxin cause illness? |
Tetanus toxin blocks glycine from inhibitory interneurone Glycine can not prevent the release of acetylcholine from motor end plate Muscles constantly stimulated to contract Paralysis + asphyxiation |
|
|
How does cholera cause illness |
Internalised A subunit activates adenylate cyclase disrupts natural sodium ion influx causes mass loss of water from blood into lumen of small intestine cause excessive diarrhoea |
|
|
How can endotoxins lead to death? |
haemorrhagic shock induced by large inflammatory response |
|
|
What is the test required to confirm that any gram negative based product does not contain endotoxins? |
LAL assay Limulus amebocyte lysate can detect as little as 10 pg/ml or more |
|
|
What is pneumolysin and what does it cause? |
virulence factor for gram + streptococcus pneumoniae pore forming toxin lyse cells interfer with cell function interfer with soluble part of immune system |
