inquiry question 1 module 7 Flashcards
How are diseases transmitted?
definition of disease
abnormal condition which affects the bodily functions of an organism
definition of non-infectious disease
Cannot be transmitted from one person to another except from inheritance eg. cancer
definition of infectious disease
diseases that can be transmitted from one person to another not by inheritance
- caused by pathogens and are contagious
eg. covid, flu
communicable disease
animal-animal plant-plant
microbes
microorganisms that cause disease
microorganisms
anything that is small that you can’t see with an unaided eye
define pathogen
disease causing organism that are spread through vectors such as mosquitoes
- can be microscopic or macroscopic
virulence factors
enable the pathogen to inhabit its host more effectively and may even be able to evade destruction by antibiotics
types of pathogens
non-cellular: viruses, prions
unicellular: bacteria, protozoa, fungi
multicellular: fungi
infection
invasion and reproduction of a pathogen that elicits a response from the body
name pathogens
bacteria, fungi, protozoan, prion, viruses, macroparasites
bacteria
living single-celled prokaryotes
- reproduce asexually through binary fission but can also horizontally transfer genes
- Produce toxins which kill or significantly damage cells and tissues and damage cells
cell wall, cell membrane, cytoplasm, ribosomes, nucleoid, flagellum
eg. H.Pylori, tonsilitis
how are bacteria classified
by shape
cocci (spherical) - tonsilitis
bacilli (rods) - anthrax
spirilla (spiral) - syphilis
vibrio (curved) - cholera
microflora
ecosystem of bacteria and other microbes that live in or on humans
antibiotics
medications that target bacteria and kill them preventing them from multiplying
fungi
unicellular or multicellular eukaryotes
- reproduce asexually and sexually
- heterotrophic
- eg. yeasts, mould, mushrooms
- cell walls made of chitin
- Essential for the decomposition and nutrient cycling in ecosystems
- Used to produce antibiotics → makes antibacterial chemicals that are in competition with bacteria for nutrients creating an antibacterial compound
eg. ringworm, thrush
protozoa
unicellular eukaryotes
- heterotrophic organism
- Reproduce asexually through binary/multiple fission or sexually
- usually found in soil and water
- lack cell walls
survival:
become dormant cysts that can survive adverse conditions such as high temperatures, harsh chemicals and long periods without water, nutrients or oxygen
eg. giardia, malaria
heterotrophic
feed on others and do not make tier own food
protozoa classification
by locomotion
- flagella
- cilia
- pseudopods
infected animals of protozoa
carrier animals and sources of infection for susceptibel animals
eg. plasmodium lives in both human and mosquito where the first host the mosquito acts as a vector
prions
non-living non-cellular abnormally structured proteins that cause other proteins to also become abnormally structured
- Altered proteins build up and cause tissue damage and death
- cannot be easily destroyed, incurable
- long incubation period in the body
eg. scrapie, bovine spongiform encephalopathy
viruses
non-cellular non-living infectious agents
Consists of a single or double stranded RNA or DNA enclosed in a protein coat which enable it to recognise suitable host cells
- inserts their DNA or RNA into host cell
- host cell starts producing more DNA/RNA and viral proteins
-Once parts have been assembled into new viruses → burst out of cell and start infecting more cells
eg. aids, influenza, polio
macro-parasites
multicellular eukaryotic parasites that can be seen with the naked eye
endoparasites (inside) ectoparasites (outside)
eg. tapeworm, guineaworm, ticks
adaptations to pathogens
as skin usually prevents entry of pathogens -> vectors (penetrate the skin barrier eg. mosquitoes)
eg. black death vector borne disease
- use symptoms such as coughing to exit the host to transmit to a new host eg. cholera
- changes behaviour of the host, eg. horsehair worms infect crickets cause them to seek light and worm crawls out and swims away
bacterial adaptations to pathogens
- live within a biofilm that offers protection from host immune system responses
- flagellum: Allows bacteria to move around the host or burrow into mucus layer of tissues
- Fimbraie ( long sticky threads which attach to the wall and prevent it from being washed away Allows bacteria to move around the host and prevents it from being dislodged from the urinary tract
) UTI by attaching to the wall
- produces enzymes: help spread
H.Pylori uses its spiral shape to burrow into the mucous of the stomach, flagella also aids the movement, also produces enzyme UREASE hat catalyses conversion of urea to ammonia
viral adaptations to pathogens
antigenic drift: Random mutations change the structure of antigens on the surface of the virus, so it is no longer reconciled by the immune system
antigenic shift: change in HA and NA due to recombinant events between two strains of viruses
to battle this vaccines are developed
chain of infection
- if chain is broken disease can be prevented
reservoir
portal of exit
mods of transmission
portals of entry
susceptible host
reservoir:
place where the pathogen can live grow and reproduce within people, food or water
portal of exit:
in order to be infectious → pathogens must have a way of leaving the reservoir → Blood, bodily fluid, skin eg. tapeworm
modes of transmission
the way that the pathogen spreads from the reservoir to the next susceptible host eg. physical droplets
portals of entry
ways that the infectious agent can gain entry into susceptible host , mucous membranes
susceptible host
organism usually has traits to be vulnerable to disease eg. immune deficiency
modes of transmission
direct contact
indirect contact
vector transmission
direct contact transmission
Physical contact between infected person and susceptible person
eg. sexually transmitted infections, coughing/sneezing
indirect contact transmission
No direct human-to-human contact
eg. Airborne transmission → measles virus hangs in the air after infected person walks past , contaminated objects, contaminated food and water
vector transmission
involves bite from animal or insect
eg. lyme disease from tic, heart worm
example of epidemic tranission
EBOLA
mortality rate of 50%
- Transmitted through people with close or direct contact with bodily fluids → blood, faeces, vomit
- prevention: cleaning and disinfection of surfaces and objects, avoiding contact with infected persons or their bodily fluids, wearing protective gear when interacting with infected persons
- factors contributing to spread: Poor public health infrastructure
High population mobility
CORONAVIRUS
epidemic
sudden increase in the occurrence of a particular disease within a certain area
endemic level
Normal base level of disease occurence
pandemic
If expands to a wider area such as multiple countries and effects a high percentage of the population
microbiological culture method
method used to multiply microbes under controlled conditions
Smear sources of microbes such as contaminated water onto nutrient-filled agar plates
Quickly replace lid on petri dish and seal with sticky tape
Warm plates in incubator for several days
Count number of colonies that form and distinguish different species or strains by their size, shape, texture and colour
IV: type of water being used
DV: number/type of colonies on agar plate after inoculation
CV: type of agar, amount of agar, days incubated, temperature, volume of water sample
safety: Petri dishes should not be opened, samples autoclaved, protective gear, wipe down surfaces
robert koch
determined that each disease is caused by a specific micro-organism
proved that bacteria was the cause of anthrax
- proved diseases could be transmitted by blood: Inoculated mice with blood from infected blood and they died, Inoculated mice with healthy animal blood and they remained healthy
- invented methods for cultivating pure cultures of bacteria
4 postulates
1. The microorganism must be found in excess numbers in all diseases organisms and must be absent from healthy organisms
The microorganisms must be isolated from the diseased organism and grown in pure culture
The cultured microorganisms must be capable of reproducing the same disease and a healthy organism upon inoculation
The microorganism must finally be re-isolated and re-cultured from the inoculated and diseased organism → this cultured microorganism must be identical to the original microorganisms from 1
both koch and pasteur
Laid down the foundations for the Germ Theory of Disease: idea that germs (microorganisms) cause disease when they invade or live inside the body
louis pasteur
founded pasteurisation Suggested that preventing entry of microorganisms into body is a good way to reduce infection through his swan neck experiment
spontaneous generation
organisms come from inanimate objects
germ theory of disease
idea that germs of microorganisms cause disease when they invade or live inside the body
pasteurs methodology
Two swan-neck flasks with the same volume of nutrient broth
Boiled broth inside the flasks to kill any microbes that were already present in the broth and in the flask/on the glass with a bunsen burner
Broke off the wan-neck off one flask and left flasks in a warm area
Results:
resulst:
- Flask with snapped neck changed colour and started to smell bad other one was fine
- It was exposed to microbes that could fall from the air into the broth that began growing which changed the colour and smell. The one without the broken neck also allowed air to enter but trapped any microbes in the S-shaped tube.
proved: presence of microbes in the air caused growth, disproved theory of the spontaneous generation and postulated the germ theory
two types of disease
endemic: diseases consistently present within a country or region
exotic: introduced
factors contributing to risk of disease
- mobility
- antimicrobial resistance
- loss of genetic diversity (eg irish potato plight) (transgenic organisms)
- esticide resistance
ways pathogens attack plants
biotrophs: pathogens that live and feed on living tissue
nectotrophs: produce toxins and enzymes that quickly overwhelm the plants defences and kills the cells they feed on
australia and plant diseases
Australia has strict regulations about the introduction and movement of plant material across international borders
- Banned or diseased material can be discarded and destroyed
types of plant pathogens
- plant fungi
- plant bacteria
- plant viruses
- plant macroparasites
plant fungi
- secretes enzymes that break down plant structures → cuticle or cell wall
- eukaryotic, heterotrophic, chitinous wall
- hyphae: long thread like filaments that spread though the plant tissue and absorb nutrients
- sporangia: reproductive parts of fungus that produce spores
eg. powdery mildew, down mildew
symptoms of plant fungi
- powder blotches white
- furry white growth
inhibits photosynthesis
plant bacteria
These include humid, warm weather, overcrowding of plants, inappropriate soil conditions (water, nutrients, pH and salinity) and poor air circulation
- used for transgenic organisms
black rot
plant viruses
- Replicate themselves through hijacking the transcription and translation process of the host cells
eg. cucumber mosaic virus
plant virus symptoms
puckered leaves
plant macro-parasites
aphids: insects that feed on the phloem of plants
- vectors of disease eg. aphids: cucumber mosaic disease
prevention: insecticides
school examples of plant diseases
panama banana disease
- fungus
- yellowing of leaf
- farming operations have been used for prevention
- quarantine rules in queensland
- effects its life as the stem splits
citrus canker
- bacterium
- small spots
- quarantine methods
