2.5 Parasitism Flashcards
(78 cards)
1
Q
ecological niche
A
multi-dimensional summary of tolerances and requirements of a species
2
Q
multi-dimensional summary of tolerances and requirements of a species
A
ecological niche
3
Q
what is occupied in the absence of any interspecific competition
A
fundamental niche
3
Q
when is a fundamental niche occupied
A
in the absence of any interspecific competition
4
Q
when is a realised niche occupied
A
in response to interspecific competition
5
Q
what is occupied in response to interspecific competition
A
realised niche
6
Q
what happens as a result of interspecific competition
A
competitive exclusion can occur, where the niches of two species are so similar that one declines to local extinction
7
Q
when does competitive exclusion occur, where the niches of two species are so similar that one declines to local extinction
A
as a result of interspecific competition
8
Q
what happens when the realised niches are sufficiently different
A
potential competitors can co-exist by resource partitioning
9
Q
when will potential competitors can co-exist by resource partitioning
A
when the realised niches are sufficiently different
10
Q
parasitism
A
a symbiotic interaction between a parasite and its host (+/-)
11
Q
a symbiotic interaction between a parasite and its host (+/-)
A
parasitism
12
Q
what does a parasite gain
A
nutrients/energy at the expense of its host
13
Q
reproductive potential of parasite/host compared to predator-prey relationship
A
unlike in a predator–prey relationship, the reproductive potential of the parasite is greater than that of the host
14
Q
niche of most parasites
A
have a narrow (specialised) niche as they are host-specific
15
Q
what mostly have a narrow (specialised) niche as they are host-specific
A
parasites
16
Q
parasites being degenerate
A
as the host provides so many of the parasite’s needs, many parasites are degenerate, lacking structures and organs found in other organisms
17
Q
two types of parasites
A
- ectoparasite: lives on the surface of its host
- endoparasite: lives within the tissues of its host
18
Q
- ectoparasite: lives on the surface of its host
- endoparasite: lives within the tissues of its host
A
two types of parasites
19
Q
what do some parasites require
A
- only one host to complete their life cycle
- many parasites require more than one host to complete their life cycle
20
Q
definitive host
A
the organism on or in which the parasite reaches sexual maturity
21
Q
the organism on or in which the parasite reaches sexual maturity
A
definitive host
22
Q
vector importance for parasites
A
plays an active role in the transmission of the parasite and may also be a host
23
Q
plays an active role in the transmission of the parasite and may also be a host
A
vector importance for parasites
24
malaria (5)
- an infected mosquito, acting as a vector, bites a human
- plasmodium enters the human bloodstream
- asexual reproduction occurs in the liver and then in the red blood cells. when the red blood cells burst, gametocytes are released into the bloodstream
- another mosquito bites an infected human and the gametocytes enter the mosquito, maturing into male and female gametes, allowing sexual reproduction to now occur
- the mosquito can then infect another human host
25
what is malaria caused by
plasmodium
26
what is schistosomes caused by
schistosomiasis
27
schistosomiasis (3)
- schistosomes reproduce sexually in the human intestine
- the fertilised eggs pass out via faeces into water, where they develop into larvae. The larvae then infect water snails, where asexual reproduction occurs
- this produces another type of motile larvae, which escape the snail and penetrate the skin of a human, entering the bloodstream
28
virus
parasite that can only replicate inside a host cell
29
parasite that can only replicate inside a host cell
virus
30
what do viruses contain
genetic material in the form of DNA or RNA, packaged in a protective protein coat
31
what contains genetic material in the form of DNA or RNA, packaged in a protective protein coat
viruses
32
what are some viruses surrounded by
a phospholipid membrane derived from host cell materials
33
what are surrounded by phospholipid membrane derived from host cell materials
some viruses
34
what does the outer surface of viruses contain
antigens that a host cell may or may not be able to detect as foreign
35
viral life cycle stages
- infection of host cell with genetic material
- host cell enzymes replicate viral genome
- transcription of viral genes and translation of viral proteins
- assembly and release of new viral particles
36
RNA retroviruses
- RNA retroviruses use the enzyme reverse transcriptase to form DNA, which is then inserted into the genome of the host cell
- viral genes can then by expressed to form new viral particles
37
- _____________ use the enzyme reverse transcriptase to form DNA, which is then inserted into the genome of the host cell
- viral genes can then by expressed to form new viral particles
RNA retroviruses
38
transmission
the spread of a parasite to a host
39
the spread of a parasite to a host
transmission
40
virulence
the harm caused to a host species by a parasite
41
the harm caused to a host species by a parasite
virulence
42
how are ectoparasites and endoparasites transmitted
- ectoparasites are generally transmitted through direct contact
- endoparasites of the body tissues are often transmitted by vectors or by consumption of intermediate hosts
43
- ___________ are generally transmitted through direct contact
- ____________ of the body tissues are often transmitted by vectors or by consumption of intermediate hosts
ectoparasites, endoparasites
44
factors that increase transmission rates
- the overcrowding of hosts when they are at high density
- mechanisms, such as vectors and waterborne dispersal stages, that allow the parasite to spread even if infected hosts are incapacitated
45
- the overcrowding of hosts when they are at high density
- mechanisms, such as vectors and waterborne dispersal stages, that allow the parasite to spread even if infected hosts are incapacitated
factors that increase transmission rates
46
host behaviour and parasites
- host behaviour is often exploited and modified by parasites to maximise transmission
- the host behaviour becomes part of the extended phenotype of the parasite
- parasites often suppress the host immune system and modify host size and reproductive rate in ways that benefit the parasite growth, reproduction, or transmission
47
parasites exploiting host behaviour examples
- alteration of host foraging
- movement
- sexual behaviour
- habitat choice
- anti-predator behaviour
48
- alteration of host foraging
- movement
- sexual behaviour
- habitat choice
- anti-predator behaviour
host behaviour modifications by parasites
49
immune response to parasites in mammals aspects
non specific and specific aspects
50
non specific defences against parasites
physical barriers
chemical secretions
inflammatory response
phagocytes
natural killer cells destroying cells infected with viruses
51
physical barriers
chemical secretions
inflammatory response
phagocytes
natural killer cells destroying cells infected with viruses
non specific defences against parasites
52
examples of non specific defences against parasites
- epithelial tissue blocks the entry of parasites
- hydrolytic enzymes in mucus, saliva and tears destroy bacterial cell walls
- low pH environments of the secretions of stomach, vagina and sweat glands denatures cellular proteins of pathogens
- killing of parasites using powerful enzymes contained in lysosomes, by engulfing them and storing them inside a vacuole in the process of phagocytosis
- natural killer cells can identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis
53
- epithelial tissue blocks the entry of parasites
- hydrolytic enzymes in mucus, saliva and tears destroy bacterial cell walls
- low pH environments of the secretions of stomach, vagina and sweat glands denatures cellular proteins of pathogens
- killing of parasites using powerful enzymes contained in lysosomes, by engulfing them and storing them inside a vacuole in the process of phagocytosis
- natural killer cells can identify and attach to cells infected with viruses, releasing chemicals that lead to cell death by inducing apoptosis
non specific defences against parasites
54
specific cellular defences against parasites
- a range of white blood cells constantly circulate, monitoring the tissues
- if tissues become damaged or invaded, cells release cytokines that increase blood flow resulting in non-specific and specific white blood cells accumulating at the site of infection or tissue damage
- mammals contain many different lymphocytes, each possessing a receptor on its surface, which can potentially recognise a parasite antigen
- binding of an antigen to a lymphocyte’s receptor selects that lymphocyte to then divide and produce a clonal population of this lymphocyte
- some selected lymphocytes will produce antibodies, others can induce apoptosis in parasite-infected cells
- antibodies possess regions where the amino acid sequence varies greatly between different antibodies
- this variable region gives the antibody its specificity for binding antigen
- when the antigen binds to this binding site the antigen-antibody complex formed can result in inactivation of the parasite, rendering it susceptible to a phagocyte, or can stimulate a response that results in cell lysis
- memory lymphocyte cells are also formed
- initial antigen exposure produces memory lymphocyte cells specific for that antigen that can produce a secondary response when the same antigen enters the body in the future. When this occurs antibody production is enhanced in terms of speed of production, concentration in blood and duration
55
endoparasites immune evasion
mimic host antigens to evade detection and modify host immune response to reduce their chances of destruction
56
what mimics host antigens to evade detection and modify host immune response to reduce their chances of destruction
endoparasites immune evasion
57
atigenic variation effect in parasites
- allows parasites to change between different antigens during the course of infection of a host
- may also allow re-infection of the same host with the new variant
58
- allows parasites to change between different antigens during the course of infection of a host
- may also allow re-infection of the same host with the new variant
atigenic variation effect in parasites
59
how do some viruses escape immune surveillance
- by integrating their genome into host genomes, existing in an inactive state known as latency
- the virus becomes active again when favourable conditions arise
60
- by integrating their genome into host genomes, existing in an inactive state known as latency
- the virus becomes active again when favourable conditions arise
how some viruses escape immune surveillance
61
epidemiology
the study of the outbreak and spread of infectious disease
62
the study of the outbreak and spread of infectious disease
epidemiology
63
herd immunity threshold
the density of resistant hosts in the population required to prevent an epidemic
64
the density of resistant hosts in the population required to prevent an epidemic
herd immunity threshold
65
what do vaccines contain
antigens that will elicit an immune response
66
what contain antigens that will elicit an immune response
vaccines
67
what makes it difficult to find drug compounds that only target the parasite
the similarities between host and parasite metabolism
68
what does the similarities between host and parasite metabolism mean its difficult to do
to find drug compounds that only target the parasite
69
what must be reflected in the design of vaccines
antigenic variation
70
why is it difficult to design vaccines
some parasites are difficult to culture in the laboratory
71
what does some parasites being difficult to culture in the laboratory mean
its difficult to design vaccines
72
conditions where parasites spread most rapidly
- overcrowding or tropical climates
- overcrowding can occur in refugee camps that result from war or natural disaster or rapidly growing cities in LEDCs
- these conditions make co-ordinated treatment and control programs difficult to achieve
73
what thrives in overcrowding or tropical climates
parasites
74
control strategies for parasite spread
- civil engineering projects to improve sanitation
- co-ordinated vector control
75
- civil engineering projects to improve sanitation
- co-ordinated vector control
control strategies for parasite spread
76
benefits of parasite control
reduce child mortality and result in population-wide improvements in child development and intelligence, as individuals have more resources for growth and development
77
reduce child mortality and result in population-wide improvements in child development and intelligence, as individuals have more resources for growth and development
benefits of parasite control
