Diseases Flashcards
How do bacteria cause disease symptoms?
Usually produce toxins
How do fungi cause disease symptoms?
Secrete digestive enzymes that digest living cells, allowing the fungus to spread through tissue
How do protoctista cause disease symptoms?
Often by consuming cell material of host
How do viruses cause disease symptoms?
Insert genetic material into host’s DNA, taking control of cell metabolism
What is a communicable disease?
A disease caused by a pathogen, which can be transmitted to another organism
What is a pathogen?
A disease causing organism
What is potato blight?
A disease caused by a protoctist, where hyphae penetrate cells, destroying leaves, tubers and fruit
What is ring rot?
A disease caused by a bacterium, where vascular tissue in leaves and tubers is destroyed
What is TMV?
Tobacco Mosaic Virus, a viral disease which causes mosaic patterns of discolouration on leaves, flowers and fruit
What is Black Sigatoka?
A fungal disease, where hyphae penetrate and digest cells in leaves, causing them to turn black in colour
What is Malaria?
A disease caused by the plasmodium protoctist, which infects erythrocytes and liver cells, causing fever and fatigue
What is TB?
Tuberculosis is a bacterial disease which destroys lung tissue, resulting in coughing, fatigue and chest pain
What is HIV/AIDS
Human immunodeficiency disease infects t helper cells thereby inhibiting the immune system and leaving the body very vulnerable to other infections
What is athlete’s foot?
A fungal disease where skin on people’s feet is digested, causing cracking and itchiness
What is callose?
A polysaccharide that is deposited in plant cell walls, plasmodesmata and sieve plates to prevent pathogens being able to spread to other cells within a plant
What chemical defences do plants have to prevent disease?
Insect repellants (e.g. citronella), insecticides, antibacterials (glossypol), antifungals (saponins), anti-oomycetes, general toxins (cyanide compounds)
Compare the structures of callose and cellulose
Both (largely) linear, both polysaccharides of ß-glucose, callose has 1,3 glycosidic bonds whereas cellulose has 1,4 glycosidic bonds, cellulose has cross links, callose is helical and has some branching
What are cytokines?
Cell-signalling molecules that attract phagocytes to sites of infection
What do opsonins do?
Bind to pathogens and mark them for phagocytosis (phagocytes have receptors that bind to opsonins)
What are primary defences? What are some examples?
Defences that prevent pathogens from entering the body.
Skin, conjunctiva (membrane covering the eye), mucus, ciliated epithelia, acidic conditions in stomach and vagina
What are blood clotting systems for?
Repairing primary defences when they get damaged (particularly the skin)
What is inflammation and how does it help?
Inflammation is when mast cells release histamine, causing blood vessels to dilate, causing more plasma to move into the tissue fluid and an increase in temperature. This increased temperature slows the rate of pathogen production and the inflammation is thought to help isolate pathogens.
How does phagocytosis work?
A phagocyte engulfs a pathogen and encloses it within a membrane. A lysosome fuses with the phagocyte to form a phagolysosome, and releases digestive enzymes with digest the pathogen and destroy it
What is the role of t helper cells?
To release cytokines, which stimulate b cells and other t cells and attract phagocytes to sites of infection
What is the role of t killer cells?
Release performs which break down/damage membranes of pathogens
What is the role of t memory cells?
Recognise antigens from previous infections (known as immunological memory)
What is the role of t regulatory cells?
Prevent autoimmune reponses
What is the role of plasma cells?
Produce antibodies
What is the role of b effector cells?
Divide to form plasma cell clones
What is the role of b memory cells?
Remember specific antigen (enabling rapid secondary immune response)
What are antigens?
Molecules on cells (or viruses) that the immune system can use to detect infection
What is opsonisation?
When antibodies act as opsonins, speeding up phagocytosis
What is agglutination?
When antgen-antibody complexes clump together, making the clump too large to enter cells and meaning several pathogens can be engulfed at once
What is neutralisation?
When antibodies bind to toxins, rendering them harmless
What are autoimmune diseases?
When the immune system malfunctions and stops recognising self antigens. The body’s own cells are attacked by its own immune system
When is an animal immune?
When it can be infected by a pathogen without developing any symptoms of the disease
What is the principle of vaccination?
To persuade the body to produce antibodies and memory cells against a particular pathogen without the person contracting the disease
