4.1.1 Flashcards
Name 4 groups of pathogen that can cause communicable diseases
Bacteria
Fungi
Protoctista
Viruses
How does mycobacterium tuberculosis cause disease
Triggers inflammatory response by infecting phagocytes in lungs
Bacteria becomes active and destroy lung tissue
What does ring rot do
Affects potatoes and aubergines and damages leaves and fruits
Bacterial disease
What causes bacterial meningitis
Often menigococcal bacteria A B C W X Y
Damages membrane around brain
Transmitted by droplet infection and direct contact with saliva
How are bacteria’s classified
Basic shapes-rod,spherical, spiralled, corkscrew, comma
Cell walls via gram staining
Positive=purple/blue
Negative= red
Describe three viruses
Tobacco mosaic virus- transmitted via infected sap, damages leaves, flowers+ fruits, affects tomato and cucumbers , causes stunted growth
HIV - attachment protein binds to complementary CD4 receptor on Th cells, destroys immune system
Influenza - transmitted via droplet infection,contact with mucus containing, injects viral RNA into CEC- destroys
Define three bacterial diseases
Tuberculosis
Meningitis
Ring rot - affects potatoes and aubergines + damages leaves and fruit
Describe 3 fungal infections
Black Sigatoka -affect bananas, attack leaves
Ringworm-causes grey, white, crusty circular patches
Athletes foot- in human causes cracking and scaling
What are Protoctists and explain blight
Eukaryotic cell
Causes malaria,potato/tomato late blight
Blight -transmitted via spores and causes cell death in leaves
What causes malaria
Mosquitoes act as vector for plasmodium spp
Parasite reproduce asexually in red blood cells in liver, causing lysis
How are communicable pathogens transmitted directly
Inhalation
Skin to skin or exchange of fluids
Penetrate skin
How are communicable pathogens transmitted indirectly
Consumption of contaminated food
Via a vector
Spores
Name 4 physical barriers to pathogens entry in plants
Cellulose cell walls
Waxy cuticle
Lignified layer
Old vascular tissue blocked to prevent pathogens from spreading in plant
Describe two mechanical and one chemical response to infection in plant
Guard cells close stomata
Polysaccharide cal lose deposited between plant cell walls and plasma membrane to limit spread
Produce anti microbial chemicals
What are the primary non specific defences that KEEP PATHOGENS out
Skin -physical barrier of keratin layer
Mucous membrane - trap pathogens and May secrete anti microbial enzymes
Hydrochloric acid
Harmless bacteria in gut and skin to increase interspace competition with pathogens
What are secondary defences that help get rid of pathogens
Blood clotting
Inflammation
Expulsive reflexes
What happens in blood clotting
Blood clot rapidly seal wound
Thromboplastin -enzyme that triggers lots of reaction resulting in formation
Serotonin -smooth muscle in the walls of the blood vessels contract, reduces supply of blood to area
What occurs in inflammation
Can be triggered by tissue damage
Damaged tissue activate mast cells which release histamines and cytokines
What are expulsive reflexes
Force foreign substance out
Irritation causes sneezes in mucous membrane
Irritation of ciliated epithelium in respiratory tract causes coughing
Outline the process of inflamation
Damages vessels leads to release of histamines causing vasodilation
Blood flow and permeability of blood vessel increases
White blood cell and plasma move into the infected tissue
How does phagocytes destroy pathogens
Pathogens produce chemicals that attract phagocytes
Phagocytes engulf pathogen via endocytosis to form a phagosome
Lysozyme digest and destroy pathogens
What is an antibody? Describe its structure
Proteins secreted by plasma cells
Quaternary structure
2 long identical polypeptide chains -heavy
2 shorter identical polypeptide chains-light
Held by disulfide bridges
Binding site on variable region Specific tertiary structure complementary to antigen
How do antibodies lead to the destruction of a pathogen
Neutralise toxins so they became insoluble
Act as agglutinins so pathogen clump together
Opsonises for phagocytes
Name two types of specific immune response
Cell mediated
Hum-oral
Outline the process of cell mediated response
Selection: Complementary Th lymphocytes bind to foreign antigen on antigen presenting cell
Expansion : Th cells (rapid mitosis) -became memory cells or trigger hum oral response
Expansion: cytotoxic T cells
Action - secrete enzyme perforin - destroy infected cells
Outline the process of hum oral response
Selection: Complementary Th lymphocytes bind to foreign antigen on antigen presenting T cells
Expansion: complementary B lymphocytes
Differentiate: B cells into plasma cells
Action : plasma cells secrete antibodies with complementary variable region to antigen
Describe the structure and function of B lymphocytes
B cells differentiate into plasma cells to secrete antibodies
Describe T lymphocytes
3 types
T helper - secrete cytokines
T killer - secrete perforin
T regulator - suppress other immune cells to prevent autoimmune disease
What are memory cells
Specialised Th/B cells produced from primary immune response
Remain in low levels in the blood
Can divide very rapidly
