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Biology old > Communicable Diseases > Flashcards

Communicable Diseases Flashcards

1
Q

name 4 types of pathogen that can cause communicable diseases

A

bacteria
fungi
protoctista
viruses

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2
Q

how does myobacterium tuberculosis cause disease

A

triggers inflammatory response by infecting phagocytes in lungs
infected phagocytes sealed in waxy coated tubercles so bacteria remain dormant
first infection has no symptoms
if another factor weakens immune system, bacteria becomes active and destroys lung tissue

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3
Q

how does HIV result in symptoms of AIDS

A

attachment proteins bind to complementary CD4 receptors on Th cells
HIV replicates inside Th cells killing or damaging them
AIDS develops when there were too few Th cells for immune system to function
individuals cannot destroy other pathogens and suffer from secondary diseases

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4
Q

how does tobacco mosaic virus cause disease

A

affects plants and transmitted via sap
contains ssRA which is directly transcribed by host cell to assemble new virions
virions enter cells via plasmodesmata then enter xylem and phloem
causes stunted growth

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5
Q

how does the influenza virus cause disease

A

transmitted via droplet infection
injects viral RNA into ciliated epithelial cells of throat and lungs
viral RNA hijacks cell biochemistry to produce new virions
cell lysis releases virions

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6
Q

what causes malaria

A

female mosquito acts as vector when it transfers saliva to another organism during feeding
parasite reproduces asexually in red blood cells causing lysis

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7
Q

what causes potato blight

A

protoctista behaves similarly to a fungus
mainly transmitted via spores

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8
Q

what causes ring rot

A

bacteria mainly transmitted by planting infecting seeds

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9
Q

describe 3 fungal infections

A

sac fungus causes leaf spot disease black Sigatoka in banana plants
ringworm transmitted through direct contact
athletes foot

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10
Q

how are communicable pathogens transmitted directly

A

inhalation
skin to skin contact or exchange of fluids
penetrate skin actively using enzymes or passively

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11
Q

how are communicable pathogens transmitted indirectly

A

consumption of contaminated foods
via a vector
spores

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12
Q

how do living conditions affect transmission

A

overcrowding increases direct transmission
climate determines which organisms can survive
social factors determine how quickly people are treated

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13
Q

name 4 physical barriers to pathogen entry in plants

A

cellulose cell walls
lignified layer
waxy upper cuticle
old vascular tissue blocked to prevent pathogens from spreading inside plant

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14
Q

describe 2 mechanical responses to infection in plants

A

guard cells close stomata
thick polysaccharide callose is produced and deposited between cell wall and plasma membrane to increase entry distance

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15
Q

what is necrosis

A

injury activates intracellular enzymes in plants that kill cells near the site of infection to prevent pathogen from spreading

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16
Q

describe the chemical defences plant use

A

terpenoids-act as antibacterials
phenols-interfere with digestion
alkaloids-provide bad tastes
defensins- inhibit transport channels hydrolytic enzymes-break down cell wall of invading organism

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17
Q

name 5 barriers to infection in animals

A

skin is tough keratin layer
blood clotting prevents pathogens entering through skin lesions
hydrochloric acid in stomach kills bacteria
harmless bacteria increase interspecific competition with pathogens
mucous membranes trap pathogen

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18
Q

what are expulsive reflexes

A

body attempts to force foreign substances out

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19
Q

outline the process of inflammation

A

damaged vessels release histamines causing vasodilation
blood flow and permeability of blood vessels increases
white blood cells and plasma move into infected cells

20
Q

how does blood clotting occur

A

blood platelets form plug and release chemicals that enhance clotting prothombin changes into thrombin-its active form
fibrinogen changes into insoluble fibres which covers wound

21
Q

how does phagocytosis destroy pathogens

A

phagocyte moves towards pathogen which may have been marked by opsonins
phagocyte engulfs pathogen via endocytosis to form a phagosome
phagosome fuses with lysosome (phagolysosome)
lysozomes digest pathogens
phagocyte absorbs the products from pathogen hydrolysis

22
Q

explain the role of antigen presenting cells

A

macrophage displays antigen from pathogen on its surface
enhances recognition by Th cells which cannot directly interfere with pathogens
secrete cytokines involved in stimulating specific immune response

23
Q

what are lysozymes

A

digestive enzymes
found in lysosomes and secretions
damage bacterial cell walls causing osmotic lysis

24
Q

name the two types of specific immune system

A

cell mediated
humoral

25
Q

outline the process of cell mediated response

A

complementary Th lymphocytes bind to foreign antigens on APC
cell signalling via secretion of interleukins stimulates
-clonal expansion of Th cells: become memory cells or trigger humoral responses
-clonal expansion of cytotoxic T cells: secrete perforin to destroy infected cells

26
Q

outline the process of humoral response

A

complementary Th lymphocyte bind to foreign antigens on antigen presenting T cells
release cytokines that stimulate cell expansion of complementary B lymphocytes
B cells differentiate into plasma cells plasma cells secrete antibodies with complementary variable region to antigen

27
Q

describe the structure and function of B and T lymphocytes

A

many specific receptors and immunoglobulins on surface
B cells differentiate into plasma cells to secrete antibodies

28
Q

what are the three types of T cells and their function

A

T helper cells-secrete cytokines
T killer cells-secrete perforin
T regulator cells-suppress other immune cells to prevent autoimmune disease

29
Q

what is an antibody

A

protein secreted by plasma cells

30
Q

describe the structure of an antibody

A

quaternary structure: two light chains held by disulfide bridges and 2 longer heavy chains
binding sites on variable regions of light chains have specific tertiary structure complementary to an antigen

31
Q

how do antibodies lead to the destruction of a pathogen

A

agglutinins form antigen-antibody complexes to enhance phagocytosis
opsonins mark microbes for phagocytes
antitoxins make toxins insoluble via precipitation

32
Q

what are memory cells

A

specialised T/B cells produced from primary immune response
remain in low levels in the blood
can divide rapidly by mitosis if an organism encounters the same pathogen again

33
Q

contrast the primary and secondary immune response

A

secondary reponse:
faster rate of antibody production
higher antibody concentration
antibody levels remain higher
pathogen usually destroyed before symptoms

34
Q

compare and contrast active and passive immunity

A

both involve antibodies
active:
memory cells=long term
time lag
lymphocytes produce antibodies
needs direct contact with antigen
passive:
no memory cells=long term
immediate
antibodies from external source
no direct contact with antigen

35
Q

give examples of passive immunity

A

passive natural=antibodies in breast milk
passive artificial=needle stick injections

36
Q

give examples of active immunity

A

active natural=humoral response
active artificial=vaccinations

37
Q

define autoimmune disease

A

immune system produces antibodies against own tissue
example=lupus results in inflammation throughout the body

38
Q

explain the principles of vaccination

A

vaccine contains dead/ inactive form of pathogen
triggers primary immune response
memory cells produced and remain in the bloodstream so secondary response is rapid and produces high concentrations of antibodies
pathogen in secondary response is destroyed without symptoms

39
Q

define endemic

A

disease occurs routinely in a geographical area

40
Q

define epidemic

A

temporary rapid increase in incidence of a disease in a geographical area

41
Q

what role do vaccines play in preventing epidemics

A

routine vaccination reduces available carriers of pathogen resulting in herd immunity
vaccinating close contacts of infected individuals limits spread of pathogen

42
Q

list some possible natural sources of medicines

A

fungi (penicillin)
plants

43
Q

what is personalised medicine

A

genome sequencing has enabled scientists to predict an individuals response to disease/medicines so prescriptions targeted

44
Q

what is synthetic biology

A

engineering that targets biochemical processes

45
Q

what are the benefits of using antibiotics

A

effectively reduce population of bacterial colony
bacteriostatic antibiotics-prevent protein synthesis
bactericidal antibiotics-prevent formation of peptidoglycan cross links in cell walls

46
Q

what are the risks of using antibiotics

A

overuse increases selection pressure for resistant strains
antibiotic resistant infections are difficult to treat

Biology old (25 decks)

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