Communicable diseases, disease prevention and the immune system Flashcards
Name different types of bacterial diseases
- Tuberculosis
- Bacterial meningitis
- ring rot (in potatoes and tomatoes )
Name the different types of viral disease
- HIV
- AIDS
- Influenza
- tobacco mosaic virus
Name the different types of protoctista disease
- Malaria
- potato/tomatoe late blight
Name the different types of fungal disease
- Black sigatoka (bananas)
- ringworm (cattle)
- Athletes foot (humans)
What is a disease?
an illness or disorder of the body or mind that leads to poor health
What are communicable diseases?
Diseases that are caused by pathogens and that can be spread between organisms
What are non-communicable diseases?
Long term degenerative diseases that aren’t caused by pathogens.
Which microorganisms are pathogens?
Bacteria, viruses, fungi, protoctists
What pathogen causes tuberculosis?
A bacteria called M. tuberculosis
What does tuberculosis do?
It infects the lungs , causing a chronic cough and bloody mucus
What pathogen causes bacterial meningitis?
A bacteria called N. meningitidis
What does bacterial meningitis do?
It causes acute inflammation in the tissue that surrounds the brain and spinal cord
What are the symptoms of bacterial meningitis ?
Fever, headache, neck stiffness, rash
What pathogen causes ring rot?
Bacteria
What is ring rot?
A disease in potato plants, where the bacteria infects the vascular tissue and prevents the transport of water, causing the plant to wilt and die
What are the symptoms of ring rot?
A characteristic black ring rot
Do viruses have standard organelles?
No
Can viruses respire?
No
How do viruses spread?
They infect host cells and hijack their machinery to replicate their own genetic material and proteins
What was the first virus ever discovered?
Tobacco mosaic virus
What are the symptoms of a plant infected by tobacco mosaic virus?
Yellowing of the leaves, mosaic pattern
What are the 3 different influenza viruses that can infect humans and cause the flu?
Influenza A, Influenza B, Influenza C
What do the Influenza viruses do?
They infect the cells that line the airways
What are the symptoms of Influenza?
High temperature, body aches, fatigue
What does HIV stand for?
human immunodeficiency virus
What does HIV do?
HIV infects the cells of the immune system and weakens the body’s immune response , so a person with HIV is more likely to get sick
What are protists/ Protoctista?
Unicellular eukaryotes
What protist causes malaria?
Plasmodium falciparum
What are the symptoms of malaria?
fever, chills and fatigue
What vector spreads plasmodium falciparum?
Mosquitoes
What pathogen causes potato blight?
Protist P.infestans
What does potato blight do to potato and tomato plants?
Destroys them and leaves them inedible
Why is the pathogen of potato blight unusual?
Because despite being a protoctist, it has fungal characteristics. E.g. the pathogen is transmitted via spores
What are the symptoms of potato blight?
small, dark brown marks on the leaves which quickly increase in size and number
Are fungi eukaryotes or prokaryotic?
They’re eukaryotes that have a similar structure to plants
What is cattle ringworm?
A fungal disease that exists on the surface of the skin
What is athletes foot?
A fungal disease that exists on the surface of the skin
What is black sigatoka?
A fungal disease in bananas that spreads through the leaves of the plant, reducing its ability to photosynthesise
What are the symptoms of Black sigatoka?
Black streaks on the leaf ( caused by the leaf dying due to lack of photosynthesis )
What is disease transmission?
the transfer of pathogens from an infected host to an uninfected host
What are the 2 types of disease transmission?
Direct transmission and indirect transmission
What is direct transmission?
The transfer of pathogens from host to host
What is indirect transmission?
When a vector transfers the pathogen to a new host
Name the forms of direct transmission
-Physical contact
- Air droplets
- Fungal spores
- Exchange of bodily fluids
-
Is it true that the form of TB caused byMycobacterium bovisoccurs incattlebut is spread to humans through contaminatedmeat andunpasteurisedmilk?
Yes
Name the forms of indirect transmission
- ## Vectors
What is an endemic?
A disease that is always present in a population - even if in very low numbers
What is an epidemic?
Where there is a large increase in the number of cases in a population (an outbreak)
What is a pandemic?
Where an epidemic occurs on a large scale and crosses international boundaries
What are the different defense mechanisms in plants?
Active and passive
What are active defense mechanisms in plants?
Active defence mechanisms in plants are activated when pathogens invade
What are passive defense mechanisms in plants?
Passive defense mechanisms are mechanisms that are always present I.e bark
What do passive defense mechanisms include?
Physical barriers and chemicals
What Physical barriers (passive defense mechanisms) does a plant have?
- Waxy cuticle
- Cellulose cell wall
- Closed stomata
- Bark
- Casparian strip
What do Physical barriers in plants do?
They make it harder for pathogens to gain entry into plants
How does the Waxy cuticle defend the plant?
Prevents viruses and bacteria from entering the leaf
How does the casparian strip defend the plant?
Pathogens can’t penetrate the casparian strip and so can’t enter the plant
What do chemical defences in plants do?
They prevent pathogens from growing on the surface of the plant by creating acidic conditions
What are some examples of chemical defences?
- Toxic compounds
- Sticky resin found in bark, this traps the pathogens so that they can’t spread
- Compounds that encourage the growth of competing microorganisms
- Enzyme inhibitors
- Receptor molecules, which detect the presence of pathogens and trigger other defence mechanisms
Name some active defence mechanisms in plants
- Cell signalling
- Hypersensitivity
-Cell walls reinforced with callose and lignin - Narrowing of the plasmodemata
- Ingrowth into the xylem vessels (tylose)
- Blockage of the phloem
What is hypersensitivity?
The rapid death of tissue surrounding the site infected by a pathogen. This deprives the pathogen of nutrients and energy from the host tissues
Where is callose deposited?
Between the cell surface membrane and the cell wall
How does the narrowing of the plasmodesmata help defend a plant against pathogens?
Callose helps to reduce the size of the channels that connect neighbouring plant cells. This means that pathogens aren’t transmitted to neighbouring plants
What is the blockage of the phloem?
Where the sieve pores are filled with callose which prevents phloem sap from being transported
What does cell signalling allow to happen?
- Allows for pathogen metabolism to be disrupted
- Delays pathogen reproduction
- Disrupts bacterial cell surface membranes
- Stimulates the release of chitinases (enzymes that break down the chitin cell walls in fungi)
What does the first line of defence do?
It prevents the entry of pathogens into the body
What makes up the fist line of defence in humans?
- Skin
- Mucous membranes
- Expulsive reflexes
- Chemical secretions
What type of barrier is the skin to pathogens?
A physical barrier
What does the skin secrete?
Sebum, which has antimicrobial properties
How is the skin an inhospitable environment for pathogens?
Because when sweat evaporates from the skin, a salty residue is left behind. This lack of moisture combined with a high salt concentration creates an inhospitable environment for pathogens to live
What do mucous membranes line?
the gut, airways and reproductive system
What do the mucous membranes consist of ?
Epithelial cells and goblet cells
What do goblet cells do?
They secrete mucous, which traps pathogens
What do the cillia do?
They move mucus and pathogens along the airway and towards the back of the throat, where the mucus is swallowed and digested by the enzymes in the stomach
What happens when a pathogen irritates the lining of an airway
It triggers an expulsive reflex; a cough or sneeze. This sudden expulsion in air expels pathogens from the respiratory tact
What are lysosomes?
antimicrobial enzymes that breakdown the cell wall of bacteria
When does the second line of defence respond?
When a pathogen manages to evade the first line of defence
What does the second line of defence include?
- Blood clotting
- Inflammation
- Wound repair
- Phagocytosis
How does blood clotting defend the body?
Because blood clotting prevents the entry of pathogens and provides a scab ( a wound) for wound healing to occur
What is inflammation?
When the surrounding area of a wound becomes swollen, warm and painful to touch