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Biodiversity, Evolution & Disease - Coggle Diagram
Biodiversity, Evolution & Disease
4.1.1 Common Pathogens & Communicable Diseases
A disease is an illness or disorder of the body or mind that leads to poor health
Each disease is associated with a set of signs and symptoms
Communicable/infectious diseases are caused by pathogens and are transmissible (can be spread between individuals within a population)
Both plants and animals can be affected by pathogens
Infectious & Non-infectious Diseases Table
Infectious diseases are caused by pathogens and can spread between organisms by physical contact, through the air, or through vectors such as mosquitoes
pathogens including:
Bacteria: range of prokaryotic organisms, Pathogenic bacteria do not always infect the hosts of cells, they can remain within body cavities or spaces
(TB) in humans
M. tuberculosis causes tuberculosis (TB) in humans
The bacteria infect the lungs, causing a chronic cough and bloody mucus
It is a disease often associated with poor hygiene and sanitation
M. bovine in cows can also transmit to humans to cause TB
N. meningitidis
Very few bacteria can cross the barrier created by the meninges (the tissue that surrounds the brain and spinal cord) however N. meningitidis crosses this barrier to cause acute inflammation
Inflammation of the meninges causes symptoms such as fever, headache, neck stiffness and a characteristic rash
N. meningitidis causes bacterial meningitis in humans
ring rot
Ring rot diseases in potato plants are caused by bacterial pathogens
The bacteria infect the vascular tissue and prevent the transport of water, causing the plant to wilt and die
The infection spreads into the potato tubers where the vascular tissue is arranged in a ring, producing the characteristic black ring of rot
Viruses: do not have a cellular structure
This means they can't respire, produce ATP, replicate genetic material or synthesise protein They infect host cells and hijack their machinery to replicate their own genetic material and proteins
diseases
The first virus ever discovered was the Tobacco Mosaic Virus (TMV) TMV infects several plant species. It causes a distinct yellowing of the leaves which produces a mosaic pattern
influenza viruses
Influenza A, influenza B and influenza C infect the cells that line the airways
They cause a high temperature, body aches and fatigue
Influenza A is the virus that causes the most cases of flu globally
It has a capsid that surrounds 8 single-stranded molecules of RNA
The human immunodeficiency virus (HIV) infects specific cells of the immune system
It is an enveloped retrovirus
The viral enzyme reverse transcriptase produces single-stranded DNA from its viral RNA
DNA polymerase synthesises double-stranded DNA from this single-stranded DNA
The double-stranded DNA is inserted into the host DNA and can remain inactive for many years
Once activated the DNA provirus is used to synthesise new viruses
Fungi:
Cattle ringworm and athletes foot are fungal diseases that exist on the surface of the skin
Black Sigatoka is a fungal disease in bananas, It spreads through the leaves of the plant, reducing its ability to photosynthesise. The lack of photosynthesis causes parts of the leaf to die; producing black streaks. Eventually, the whole leaf dies
Fungi have a similar structure to plants. Their eukaryotic cells have cell walls and large central vacuoles. However, instead of being made of separate cells, their bodies consist of filaments known as hyphae. These hyphae form a network and spread throughout a host/soil
Protoctists
Protists are unicellular eukaryotes, Plasmodium falciparum is a protist that causes severe forms of malaria in humans. This is spread by mosquitos. Infected individuals experience fever, chills and fatigue. P. infestans causes the infamous potato blight
P. infestans causes the infamous potato blight .The pathogen is unusual as it has some fungal characteristics and is transmitted by spores. The first signs of potato blight are small, dark brown marks on the leaves which quickly increase in size and number The protist destroys potato and tomato crops leaving them completely inedible
Non-infectious diseases, such as sickle cell anaemia and lung cancer, are not caused by pathogens and are not spread between organisms.