4.1.1 - communicable diseases🦠 Flashcards
structure of bacteria
prokaryote, no membrane bound nucleus or organelles
how bacteria can be classified
- by their basic shapes (rod, spherical, spiral, corkscrew, comma shapes etc)
- by their cell walls
virus structure
non living, very small, some genetic material surrounded by protein
how viruses cause disease
viruses invade living cells, where the genetic material takes over the biochemistry of the host cell to make more viruses. reproduce rapidly and evolve.
bacteriophages
viruses that infect bacteria
protoctista
a group of eukaryotic single celled microorganisms that may cause disease. they digest cells and use the cell contents to reproduce
fungi
an organism that absorbs nutrients from the environment
saphophytes
feed on dead and decaying matter
spores
form when fungi reproduce
can spready huge distances meaning they can spread diseases rapidly
pathogens that attack the host tissue directlyv
viruses - take over cell metabolism
some protocista - take over cells and break them open
fungi - digest living cells and destroy them
pathogens which produce toxins
most bacteria produce toxins to damage the host cell in some way, causing disease
some fungi may also produce toxins
ring rot
a bacterial disease in tomatoes, potatoes, and aubergines that result in the damage to the leaves.
damages the whole yield
TMV
virus that affects plants only
damages leaves, stunting growth and reducing yields
potato blight
caused by protoctista
hyphae penetrate host cells, destroying leaves
black sigatoka
fungal disease
affects banana plants by attacking and destroying leaves
hyphae penetrate and digest the leaves, reducing yield
TB
bacterial disease that damages lung tissue and suppresses the immune system so that the body cannot fight off other diseases
cureable with antibiotics and preventable by using vaccination
bacterial meningitis
bacterial infectuon of the meninges of the brain which can spread to the rest of the body causing scepticaemia and rapid death
blotchy permeable rash
antibiotics and/or vaccinations
HIV/AIDS
virus which targets T helper cells in the immune system, destroying it.
adjusts the DNA which interacts with genetic material in the body
passed by bodily fluifs
anti-retrovial drugs can slow process
influenza
viral infection of ciliated epithelial cells
kills them so airway is open to infection
mutate regularly
no cure but prevented through vaccines
malaria
caused by protoctista and spread by bites of infected mosquitos
no vaccine but preventative measures like mosquito nets
ring worm
fungal disease causing grey white crusty infectious areas of skin
anti fungal creams
methods of direct transmission
direct contact, inoculation, ingestion
direct contact
bodily fluids, skin to skin contact, faeces on hands
inoculation
through break in skin, animal bite, puncture wound
ingestion
contaminated food or drink
indirect methods of transmission
fomites, droplet infection, vectors
fomites
inanimate objects like bedding socks or cosmetics can transfer pathogens
droplet infection
minute droplets of saliva and mucus are expelled from your mouth when you talk cough or sneeze
vectors
a vector transmits communicable pathogens from one host to another,
water can also be a vector
factors affecting transmission of communicable diseases in animals
living conditions
poor nutrition
compromised immune systen
climate change
cultire and infrastructure
socioeconomic factors
indirect transmission methods in plants
soil contamination and vectors
direct transmission in plants
direct contact of a healthy plant with any part of a diseased plant
soil contamination in plants
infected plants leave spores or pathogens in the soil whuch infect the next crop
some survive the composting process so infection cycle continued
vectors in plants
wind - spores can be carried in wind
water - spores swim on the surface of water
animals - insects and birds can carry spores
humans - hands, fomites etc
factors affecting transmission of communicable diseases in plant
- planting crops that are susceptible to disease
- overcrowding
- poor mineral nutrition
- damp warm conditions
- climate change
how plants recognise an attack
receptors in the cell respond to pathogens, stimulating the release of signalling molecules that switcg on the genes in the nucleus
physical defences of plants
callose
- deposited between cell walls, acting as barriers
-lignin added
- blocks sieve plates in the phloem
chemical defences of plants
insect repellents
insecticides
antibacterial compounds including antibiotics
antifungal compounds
anti-oomycetes
general toxins
barriers to entry of pathogens in mammals
the skin - microbial substances
body tracts - mucous membranes
- lysozymes in tears urine
- Hcl in stomach
expulsive reflexes
coughing ans sneezing
occur automatically
vomiting and diarrheoa expel contents of the gut
clotting cascade
1 - platelet finds damage
2 - releases platelet plug
3 - releases thromboplastin
4 - thromboplastin and calcium and vit K converts inactive prothrobin into thrombin
5 - thrombin converts fibrogen into fibrin
6 - fibrin threads coat damaged area and trap blood cells to form clot
inflammatory response
mast cells are activated , releasing histamines/ cytokines
histamines make the blood vessels dilate causing heat so the pathogens do not replicate
cytokines - attract WBC to site
fevers
cytokines stimulate the hypothalamus to reset the thermostat and temp goes up
- inhibits pathogen reproduction
- specific immune system works faster
phagocytosis stages
- phagocytes attracted to pathogens chemicals
- recognise antigens
- engulfs the pathogen and encloses it into a phagosome
- phagosome combines with lysosome
- hydrolytic enzymes called lysosymes digest and destroy the pathogen
opsonins
chemicals that bind to pathogens and tag them so they are more easily recognisable
antibodies
Y shaped glycoproteins which bind to specidic antigens on pathogen
structure of an antibody
two identical polypeptide chains called heavy chains and two shorter chains called light chains
held together by disulfide bridges
bindinh site - known as the variable region
how do antibodies defend the body
1 - antibody acts as an opsinin so can be engulfed by pathogen
2 - no longer invade the host cells
3 - act as agglutins, making pathogens clump together
4 - act as anti toxins, making them harmless
t helper cells
have receptors that bind to antigens. produce interleukins stimulating the activity of B cells.
T killer cells
destroy the pathogen, producing perforin making holes in the cell membrane
T memory cells
live for a long time and are part of immunological memory
T regulator cells
supress immune system acting to control and regulate it
plasma cells
produce antibodies
B effector cells
divide to form plasma cell clones
B memory cells
live for a long time and provide immunological memory
describe the role of antigen presenting cells play in the immune response
- t helper cells bind to antigen presenting cells
- t helper cells produce interleukins (trigger B cells)
- t helper cells attracr macrophages, phagocytosing additional pathogens
explain the importance of the secondary immune response
reduces the risk of secondary infection
able to respond more quickly to recognised antigens
b memory cells - remember antigens and produce antibodies more quickly
t memory cells - divide rapily and produce clones of killer t cells
how is a biological advance allowing defences against pathogens to be engineered?
DNA profiling/sequencing
to identify protein signature, and aid in diagnosis/ design vaccines
