Communicable diseases part 3 Flashcards Preview

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Flashcards in Communicable diseases part 3 Deck (37):

How does aggulitinis work?

each antibody has two identical binding sites so is able to cross link by binding an antigen on one pathogen with one binding site and another pathogen with the other binding site this clumps them together then a phagocyte can engulf them at once


Whate are the advantages of aggulitinins

physically impedes them from carrying out some fuctions such as invading host cells
can easily be destroyed and recongnised
very effective against viruses


Why does the primary immune response take time

when first infected the immune system takes time to
- clonally expand
-clonal selection
- differentiation
- Lack of memory cells


why doesn't the secondary immune response take time

there are T and B memory cells so they regonise them more quickly and produce an immune response they are quicker and there is a higher concentration therefore no symptoms are felt


draw the graph on immune response times

see revision guide


What makes plants attractive to pathogens

plants have a wide range of sugars in photosynthesis these convert those sugars to many compounds such as proteins and oils which make the plant attractive to organisms


what are passive defences

passive defences are defences are defences that are present before an infection, they prevent entry and spread of pathogen by the chemical and physical ways


what are the physical defences of plants

cellulose cell wall
lignin thickening of cell walls
waxy cuticles
stomatal closure
formation of tylose


describe what role cellulose in the cell wall plays (plant passive physical defences)

it acts as a physical barrier but most plant cell walls contain a variety of chemical defences that are induced when a pathogen is detected


Describe what role the lignin thickening of the cell wall plays (plant passive physical defences)

waterproof and almost completely indigestible


Describe what role waxy cuticles play (plant passive physical defences)

prevent water collecting on cell surfaces therefore waterborne pathogens cannot survive


describe what role bark plays (plant passive physical defences)

bark contains a variety of chemical defences that work against pathogenic organisms


Describe what role stomatal closure plays (plant passive physical defences)

stomata are points of entry therefore when pathogens are detected in a part of the plant the guard cells close the stomata and trap the pathogen preventing it from spreading


Describe what role callose plays (plant passive physical defences)

large polysaccharide polymers are deposited in sieve tube elements at the end of the growing system in the sieve tube elements around sieve tube plates this blocks the flow in the sieve tube and can prevent a pathogen from spreading around the plant


Describe what role tylose plays (plant passive physical defences)

a tylose is a balloon like swelling that fills the xylem vessel, the vessel can no longer carry water and this prevents the spread of pathogens, tylose contains a high concentration of terpenes that are toxic to the pathogen


Name some chemical passive defences

some chemicals are passive such as terpenes but a lot of chemicals are active as it requires a lot of energy to make them


What are active defences

when pathogens attack specific chemicals in pathogenic cell walls, for example proteins and glycolipids, are detected by the plant cell. this increases the passive defences and secretes chemicals


Describe some active defences

- cell wall are stronger and more thickened with more cellulose
- oxidative bursts that produce highly reactive oxygen molecules are capable of damaging the cells of invading organisms
- callose between the plant cell wall and membrane near the invading pathogen, they deposit polysacchiraride polymers which impede cell wall penetration at the site of infection as well as strengthening the cell wall and blocking the plasmodesmata
- terepenoids, phenols, alkaloids, defensive proteins, and hydrolytic enzymes
- necrosis - deliberate cell suicide, this is activated by intracellular enzymes that are activated by injury they turn the leaves brown. this is when a few cells are sacrificed for the rest of the plant to survive (around the infected area), this traps the pathogen and stops it from getting nutrients and water therefore stops it from spreading
- canker - this is a sunken necrotic lesion in the woody tissue, it causes the death of cambium tissue in the bark and prevents spreading and entry


What do terepenoids do (active chemical defence)

these are essential oils that have antibacterial and antifungal properties


what do defensive proteins do (active chemical defence)

small cysteine rich proteins that have broad antimicrobial activity that act on molecules in plasma membranes of pathogens inhibiting action of ion transport channels


What do phenols do? (active chemical defences)

have antibiotic and antifungal properties, tannins found in bark inhibit attack by insects
the tannins bind to the salivary proteins and digestive enzymes such as trypsin and chymotrypsin and deactivate them.
If insects digest a high concentration of these then it stops growth and the insect eventually dies


What do alkaloids do? ( active chemical defences)

Nitrogen containing compounds such as caffeine give a bitter after taste this stops herbivores from feeding on them
also acts on metabolic reactions inhibiting or activating enzyme action this inhibits protein synthesis


What do hydrolytic enzymes do? (active chemical defences)

found in spaces between cells, they include chitinases this breaks down the chitin in fungal walls, glycanases which hydrolyse the glyosidic bonds in glycan and lysozymes which are capable of degrading bacterial cell walls


Why are new drugs needed

- new diseases are emerging
- still many diseases with no treatments
- some antibiotics treatments are becoming less effective


who accidently discovered penicillin

Alexander Flemming


who developed penicillin

Florey and Chain


what are some of the traditional remedies that were used

Morphine - sap from an unripe poopy seed head
opium - from poppies, these were both used as anaesthetics as they reduced nervous action in the central nervous system so the person could not feel pain
- willow bark used to relieve pain and fever, the active ingredient was found in 1897 and was used to reduce the side effect of stomach bleeding by adding an acetyl group this lead to the making of aspirin and ibuprofen


Name ways in which animals use medicine

- monkeys and bears and other animals rub citrus oil onto their coats as insecticides and antiseptics in order to prevent insect bites and infection


How did plants help aspirin

research into plants allowed scientists to isolate the active ingredient, they analysed the molecule then manufactured similar molecules


Why are we now using tropical plants

great diversity therefore they contain molecules that could form medicinal drugs


what does screening do

enables scientists to screen chemicals more effectively for their potential use


what do pharmaceutical companies do

they conduct research into the way microorganisms cause disease


How do drugs stop disease from spreading

if binding site between pathogens and receptor can be blocked then disease causing pathogen cannot gain access to the cell,
the glycoprotein receptor molecule can be isolated and sequenced once the amino acid sequence is known molecular modelling can be used to determine the shape of a receptor and could be used to bind to the virus itself this blocking the virus from entering T-helper cells, it also can inhibit the action of certain enzymes


How does personalised medicine work

one day it might be possible to sequence genes from individuals with a particular conditions and develop drugs for that condition


what is synthetic biology used to do

used to construct new devices and systems


Where are most antibiotics derived from

the genus streptomcyes


What can cause antibiotic resistance

misuse can cause bacteria and fungi to develop a resistance and therefore current antibiotics have a limited effect