cellular pathogens Flashcards
what are cellular pathogens?
cellular pathogens are living organisms that cause disease within a host and are capable of all functions associated with living independently such as: movement, reproduction, sensitivity, respiration, excretion and nutrition
what are the common 4 factors that all living cells share and what to they help the cell do
- genetic material
- cytosol
- ribosome
- plasma membrane
These factors help the cell live independently and not be reliant upon a host to survive
what are the types of cellular pathogens?
- protozoa
- bacteria
- parasites
- fungi
what are bacteria?
prokaryotic, unicellular organelles that lack membrane bound organelles. They are considered to be the first life on earth and can infect almost any part of the body
how do bacteria cause disease?
they cause disease in a variety of ways
- produce toxins that build up and disrupt the normal functioning of cells - such as releasing toxins that damage the cell membrane
- damage host cells directly
- interfere with the immune system
bacteria are capable of dividing rapidly once inside the host cell (every 20 minutes)
what are the shapes of bacteria and their names?
coccus (spherical) bacillus (rod-shaped) vibrio (comma shaped) spirilla (spiral) spirochaete (corkscrew)
how do we recognise allied bacteria from harmful bacteria?
A mothers milk contains some good bacteria that gets passed to the baby. This bacteria then lives in the gut and helps the baby digest food as well as recognise between good and bad bacteria
how to treat bacterial infections?
antibiotics treat bacterial infections
how do antibiotics treat bacterial infections?
antibiotics kill bacteria or slow bacterial growth
- They must be selective for bacteria, making sure that unique mechanisms or components of the harmful bacteria are targeted so that the body’s own cells are not affected
what are superbugs?
the term ‘superbugs’ is used to describe any organism that has developed a resistance to antibiotics due to the overuse and overexposure of antibiotics
usually bacteria are superbugs but fungi and parasites can develop resistance too
what are modes of transmission for types of bacterial pathogens?
bacteria have various modes of transmission including, direct contact, indirect contact, medium transmission and through vectors
what are some bacterial infections and symptoms?
scarlet fever cholera bubonic plague tuberculosis symptoms include: fever, abdominal pain, headaches, irritation in skin, constipation and diarrhoea
what are eukaryotic pathogens (types)
fungi and parasites
what are fungi
they are eukaryotic organisms that can be unicellular or multicellular
where are fungi found?
they are primarily found in terrestrial environments that are high in moisture
where do fungi cause disease
mostly affect external surfaces like the skin and are capable of causing disease in humans however they are far more problematic in plants
structure of fungi
main body of a fungus has a long filament called a hyphae branching off it
functions of hyphae
hyphae contains cytoplasm and nucleus which are responsible for the growth of fungus and secretes digestive enzymes into surroundings to help break down organic matter for nutrient absorption
how do fungi reproduce?
they spread microscopic spores in same manner in which plants produce seeds. Tiny spores formed on hyphae are picked up by wind and transported to new areas where they grow
How do fungi cause disease
- direct contact with fungal spores or digestive enzymes which cause irritation on skin
- inhalation of enzyme or spores can cause disease
- ## the parasitic nature of fungi results in cell death in plants - fungal hyphae of spores enter plants and live off plant resources. Fungi penetrate root hairs and prevent plants taking water
how to treat fungal infections
- exposure to sunlight
- limit exposure to water
- antifungal creams
- fungicides
- quarantine
- oral medication
what are protozoa?
unique unicellular organisms belonging to protist kingdom
What environments to protozoa favour?
- they favour moist environments such as waterways and soil and some species are part of the natural flora
bad thing about protozoa
- there are only a very small amount of protozoa that are considered pathogenic however there are not many vaccines or drugs against protozoa due to their complex reproductive strategy and use of multiple hosts
Protozoa are resistant to adverse conditions
modes of transmission of protozoa
mostly direct ingestion of dormant cysts and bites from insects
structure of protozoa
consist of cillia and flagella which allow the protozoa to be highly mobile
what are non cellular pathogens
they are disease causing agents that lack the cellular structures necessary for independent replication and don’t have ribosomes or cytosol. The onset of symptoms within a host is based on pathogens ability to increase numbers within a host using host cell machinery
what are non-cellular pathogens
non-cellular infectious agents that cause disease by forcing host cells to create multiple copies of the virus which infect other cells and disrupt their function. Cannot independently replicate and don’t possess cytosol or ribosomes
why are viruses called obligates?
because they can’t survive outside the host cell and therefore are obligated to infect more cells to survive
what is a virion?
outside of a cell, a virus is called a virion
what is the structure of a virus
viruses come in a wide range of shapes and sizes
they have genetic material and a protective protein shell known as a capsid
characteristics of viral genetic material
the viral genome contains nucleic acids- either DNA or RNA but not both
the genetic material used by viral DNA is universal in nature ensuring that host cell’s machinery can be used to synthesise and assemble new viral particles
what is a capsid
a protein shell that surrounds the genetic material that provides protection for the genome and houses enzymes that helps virus to enter the host cell
what is a viral envelope?
some viruses contain an external layer known as a viral envelope
- the virus ‘borrows’ a section of the host cells membrane, as it exists the cell, to use as a viral envelope
- glycoproteins embedded in the lipid membrane help virus bind and infect the host cell
how do viruses enter the cell
virus binds to the receptors on cell’s surface and then enters the cell
how are viruses transmitted between individuals
plant viruses function
they use host cell machinery to make copies of themselves
similarity between plant viruses
most plant viruses have RNA genomes and a capsid but no viral evelope
how are viruses transmitted from plant to plant
transmission usually occurs through a vector- insect feeding on one plant and carrying th virus to another plant. Virus can be transmitted into the phloem through sap and will usually move through chanells called plasmodesmata, allowing it to sprea through plants
other methods include:
-spread of infectd pollen or seeds
- agricultural practses that transfer sap from a wounded plant to a healthy one
what are bacteriophages
viruses that infect bacteria and are the most abundant biological agent on the planet
structure of a bacteriophages
they contain viral genome and a capsid and they must enter a host cell before they can replicate
how do bacteriophages work
the inject their genome into the bacterial cell upon attachment
what is epidemiology?
study of disease distribution and control
what are prions
pathogenic protein with a mutant structure that can trigger normal proteins to fold abnormally. The are associated with a range of neuro-degenerative diseases in humans and animals
things to know about prions
- they dont have any form of genetic material so they are unique in their abiliy to cause disease
how do prions cause disease
proteins that prions arise from exist naturally in the membran of neurons. In case of disease, prions are misfolded, giving rise to a mutant shape. When a misfolded protein comes into contact with the normal form, it converts into the mutant form. When enough prions are produced, they come together forming plaques that damage neaural tissue, afecting brain function known as transmissable enthalpy
how do prions spread
prions can arise spontaneously through mutation in genes that code for normal prion protiens- more commonly they are passed on through consumption of infected food
what are exotoxins and endotoxins in bacteria?
exotoxins: toxins released by bacteria into its surrounding environment
endotoxins: toxins present within a bacteria that are released when it disintergrates
what is a virus?
a non cellular pathogen that causes disease by taking over host cell machinery to rapidly produce identical virus copies which further infect host cells, disrupting normal cellular function
what are bacterial spores?
structures that bacteria form that aid in the survival of the organism under adverse environmental conditions.
how are fungal infections transmitted
through direct contact, ingestion and inhalation of spores and digestive enzymes
how do fungi cause disease in animals?
fungi are superficial so they usually infect external surfaces like the skin.
contact with digestive enzymes released from the hyphae can cause irritation and inflammation in the skin
spore inhalation into lungs and implantation of spores onto skin can also cause fungal disease
how do fungi cause disease in plants?
the parasitic nature of fungi in plants results in plant death.
Fungal hyphae or spores make their way into the plant and live on the plant’s resources. Once the fungi grows, it causes the plant’s stress, causing it to die.
what is a virion?
Virus that is outside of the host cell
what is a viroid?
A viroid is a virus that only consists of genetic material and infects plants
what is cillia in protozoan?
short microtubule projections from the cell that move to provide motility or movement of the cell
characteristics of protozoan
they are unicellular and dont contain a cell wall and are opportunistic pathogens meaning they infect host when they are weak
what does it mean when a virus is dormant?
when a virus is present within a host cell but it is inactive and therefore does no currently cause symptoms associated with the disease
