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Parasitology > Exam 1 > Flashcards

Exam 1 Flashcards

1
Q

Why is parasitology important?

A
  • Parasite resistance
  • Insecticide resistance
  • Increased mobility (popularity ni tropics and subtropics)
  • Migration of refugees from war-torn areas
  • Military service personnel coming home from
    abroad
  • Modifications of the environment
  • Climate change (diseases spread from tropics to more temperate regions)
  • Immunosuppression becoming more widespread:
  • AIDS; cancer chemotherapy; and organ transplantation
  • indiscriminate release of toxic chemicals and carcinogens into environment
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2
Q

Parasitology: study of the most common mode of life on earth

A
  • centered on animal parasites of humans, domestic animals, and wildlife

Parasite: an organism that lives in or on another organism (host) and either harms or lives at the expense of the host

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3
Q

Neutralism

A

is a lack of benefit or detriment experienced by either members of the pair of interacting organisms

-it describes interactions where the fitness of species has absolutely no effect whatsoever on that of the other

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4
Q

Competition

A

some degree of overlap in ecological niches of two populations in the same community, such as that both depend on the same food source, shelter, or other resources and negatively affect each other survival

Ex. Carnivorous animals compete for prey, Cape Buffalo (Battle at Kruger)
Ex. Plants compete for sunlight, water, nutrients, pollinators, and dispersers of fruits and seeds
Ex. The bladderwort plant (Utricularia) compete with tiny fishes for small crustaceans and insects

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5
Q

Phoresis

A

form of symbiosis when the symbiont (phoront) is mechanically carried about by its host, neither is physiological dependent on the other

-means “to carry”

Ex. bacteria on legs of a fly
Ex. fungal spores on feet of a beetle
Ex. aquatic snail eggs laid on birds feet
Ex. Dermatobia hominis (human botfly)
- female botfly deposits egg in surface of mosquito

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6
Q

How to describe groups?

A

Monophyletic: a group of taxa that includes a hypothetical ancestral taxon and al its descendants
- defined by a suite of shared-derived characters (synapomorphies) Ex. mammals
Paraphyletic: a group of taxa that includes a hypothetical ancestor but does not include all of the ancestor’s descendants
- defined by a suite of ancestral traits
(plesiomorphies) which have been modified or lost in the excluded species Ex. class Reptilia is paraphyletic by not including birds
Polyphyletic: a group of taxa that do not share a most recent common ancestor
- defined by convergent traits (homoplasies). Ex. wings of birds, bats, and butterflies

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7
Q

How to describe characters?

A

Homologous character: a character is similar (or present) in two taxa because their common ancestor had that character
Analogous character: a similar character that has the same function but different evolutionary origin
Homoplasy: is similarity NOT due to homology; resulting from convergence, parallelism or reversal
Plesiomorphic: ancestral characters; present in both the ingroup and outgroup
- uninformative character
Autapomorphic: derived character, evolutionary novelty; present only in one taxon of the ingroup
- uninformative character
Synapomorphies:
shared derived characters that set a taxon apart from related taxa and their most recent common ancestor
- informative character

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8
Q

How to describe a species?

A

Phylogeny-evolutionary hypotheses of the origin and diversification of a taxon
- treelike diagram
- relationships between taxa are shown in the branching patterns
- characters among the taxa used to produce phylogenies include: (anatomical, behavioral, physiological, or molecular attributes)
Clade: a group of organisms that includes an ancestor and all descendents of that ancestor
Ingroup: a taxon of interest
Outgroup: a related taxon chosen for the purpose of comparison, more basal
Node: internal branch point that represents the common ancestor of those descendents; a speciation event
Sistergroup: two descendents that split from the same node

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9
Q

How to identify a species?

A

Phylogenetic systematics (cladistics):
is a methodology used by systematists to infer (hypothesize) a species’ evolutionary history (phylogeny)
- pioneered by Willi Hennig (1913-1976)
- used ni the discovery of monophyletic groups (evolutionarily real entities)
- this method exclusively relies on shared derived character states (homology)

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10
Q

There are 3 basic assumptions in cladistics:

A
  1. Change in characteristics occurs in lineages or groups over time.
    - only when characteristics change are we able to recognize different lineages
  2. Any group of organisms are related by descent from a common ancestor.
    - supported by many lines of evidence
    Ex. same genetic code (DNA), biochemical pathways (glycolysis), etc.
  3. There is a bifurcating or branching pattern of cladogenesis.
    - when a lineage splits, it divides into two exactly groups
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11
Q

Investigating the evolutionary history of a taxon is not easy. Why?

A

Unfortunately, history:
- is not something we can see
- only happened once
- only leaves behind clues

Systematists use clues to try to reconstruct evolutionary history. Why?

To research the pattern of events that have led to the distribution &diversity of life.

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12
Q

Systematics

A

study of classification &biological diversity within an evolutionary context
- seek to understand the origin of diversity at all levels of classification
- includes (a) through (f)
(a) describe organism in detail
(utilize morphological and molecular characters)
(b) provide scientific names for new species
(c) preserve collections (permanent slides and voucher specimens)
(d) classification of the organisms, keys for their identification, and data on their distributions
(e) investigates their evolutionary histories
(f) considers their environmental adaptations

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13
Q

Immunity

A

Immune System: a functional system whose components attack foreign substances or prevent their entry into the body

Immunity: state in which a host is more or less resistant to an infective agent
- used in reference to resistance arising from tissues that are capable of recognizing and protecting the animal against nonself invaders

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14
Q

I. Nonspecific immunity (Innate immunity)
The First Line of Defense: Skin and Mucous Membranes
1. Skin (integumentary system) as an effective barrier against pathogens

A

A. oil &sweat glands give skin surface pH of 4-5.5
B. sweat contains lysozyme (digests bacterial cell wall)
C. normal flora include non-pathogenic bacteria &fungi
D. epidermis 10-30 cells thick, dermis 15-40 times thicker

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15
Q

I Nonspecific immunity (Innate immunity)
The First Line of Defense: Skin and Mucous Membranes
2. Mucosal Surfaces as an effective barrier against pathogens

A

A. Digestive tract
1. saliva contains lysozyme (also in tears)
2. acidic environment of stomach pH of 1.5-3.5 (concentrated HCI solution)
3. digestive enzymes ni intestine
4. nonpathogenic normal flora
5. vomiting &diarrhea may expel pathogens

B. Respiratory tract
1. pathogens trapped by mucus ni bronchi and bronchioles
2. ciliated epithelial cells sweep mucus toward the glottis
3. coughing and sneezing expels pathogens

C. Urogenital tract
1. vaginal secretions viscous and acidic
2. secretions promote growth of normal flora
3. acidic urine of both sexes may wash out pathogens

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16
Q

I. Nonspecific immunity (Innate immunity):
The Second Line of Defense
Phagocytes, inflammation, complement &interferon, cytokines & chemical signals, and antimicrobial proteins

A
  • recognizes a wide spectrum of pathogens without a need for prior exposure
  • key players include neutrophils, monocytes, and macrophages
  • these cells phagocytose pathogens and trigger the cytokine and chemokine network
  • can lead to inflammation and specific immune responses
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17
Q

How to describe Parasite Location?

A

Coelozoic: a parasite living in the lumen of a hollow organ
Ex. intestine

Histozoic: a parasite living within the tissues of a host
Ex. liver

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18
Q

Protocooperation

A

A mutually beneficial symbiosis between organisms in which the interaction is not physiologically necessary to the survival of either

Ex. Egyptian plover eats residuals from crocodile teeth
Ex. Cattle egret removes ectoparasites from the back of bovines
Ex. Hermit crab inside shell over which sea anemones live
Ex. ants and aphids

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19
Q

Mutualism

A

type of symbiosis in which both host and symbiont benefit from association
- usually obligatory
- in most cases there is physiological dependence
Ex. Termites and intestinal protozoan fauna
Ex Blood-sucking leaches and intestinal bacteria
Ex. Cleaning symbiosis: cleaner wrasse (Labroides dimidiatus)
Ex. Lichen microscopic green algae or cyanobacteria and filamentous fungi
Ex. Wucherena bancrofti and Onchocerca volvulus infected with Wolbachia
Ex. Mycorrhizae (fungus-root)
Ex nitrogen fixation, the bacteria Rhizobium spp.
Ex. Cotesia congregata (parasitord wasp) & C. congregata bracovirus (CcBV)

20
Q

Commensalism

A

a kind of symbiosis in which the symbiont (a commensal) benefits, and the host is neither harmed nor helped by the association

-means eating at the same table

Ex. Pilot fish and remoras
Ex. Entamoeba gingivalis
Ex. Barnacle on a whale
Ex. epiphytes on a tree

21
Q

Amensalism

A

asymmetrical interaction in which one organism causes a negative effect on another without being positively or negatively affected in return

Ex. bread mold Penicillium that produces penicillin, an antibiotic that kills bacteria
Ex. Black walnut tree (Juglans nigra) produces juglone, an organic compound that is toxic or growth-stunting to many types of plants

22
Q

Predation

A

animal interaction in which a predator kills its prey outright; ti does not subsist on the prey while the prey is alive

23
Q

Parasitism

A

a symbiosis in which a symbiont benefits from
the association, while it harms the host in some way or lives at the expense of the host

Ex. Ex. human infected with Guinea worm (Dracunculus medinensis)

24
Q

Both the parasite and the predator live at the expense of the host or prey; interaction occurs only if there is an encounter

A

Predator
-kills its prey
- is large relative to the prey
- has numerous prey
- is not symbiotic
- no post-encounter interaction

Parasite
- normally does not kill its host
- is small relative to the size of the host
- has only one host (or one host at each stage in its life cycle)
- is symbiotic
- post-encounter interaction is where the real action begins!

25
Q

How to describe Parasites

A

Accidental (incidental) parasite: a parasite found in host other than its normal host
- puts host and parasite into environmental conditions to which neitheris well adapted
Ex. Toxocara canis in humans (visceral larval migrans)

Permanent parasite: a parasite that lives its entire adult life within or on a host
Ex. Trichinella spiralis never sees the light of day

Temporary (intermittent) parasite or micropredators: a parasite that contacts its host only to feed and then leaves
Ex. Mosquito, bed bug, flea, etc

Parasitoid: organism that is a typical parasite early in its development, but finally kills its host during or at the completion of its early development
- often used in reference to many insect parasites of other insects
- approximately 10% of described insect species are parasitoids
Ex. Alien movies
Ex. Pseudacteon phorid

Hyperparasitism: condition in which an organism is a parasite of another parasite
Ex. Plasmodium spp. in Anopheles mosquitoes Ex. tapeworm juvenile in flea

26
Q

taxonomy

A

study of scientific classification; ordering and naming organisms
-basic subdiscipline of biology

(a) describe organism in detail
(utilize morphological and molecular characters)
(b) provide scientific names for new species
(c) preserve collections (permanent slides and voucher specimens)
(d) classification of the organisms, keys for their identification, and data on their distributions

27
Q

binomial nomenclature

A

a system in which a species is given a compound name

-Carolus Linnaeus (1707-1778), father of modern taxonomy

taxa: groups, ranging from species to the increasingly inclusive genera, families, orders, classes, phyla, kingdoms and domains

28
Q

descriptive parasitology

A

Studies performed that are non-hypothesis driven;
-Includes discovery of new parasites, parasite morphology, lifecycle trends, population survey of infected or non-infected hosts
-proper identification of parasites and hosts is essential in trying to control diseases

29
Q

How to Describe Hosts?

A

Definitive host: host in which parasite reaches sexual maturity, if no sexual maturity host most important to humans

Intermediate host : host in which parasite develops to some extent, but not to sexual maturity

Paratenic (transport) host: host in which a parasite survives without undergoing further development

Reservoir host: host that serves as a means of sustaining a parasite when it’s not infecting humans, which is typically another suitable definitive host

30
Q

Population

A

Any group of individuals, usually of a single species, occupying a given area at the same time

31
Q

mutation

A

A permanent change in a cell’s DNA and includes changes in nucleotide sequences alteration of gene position, gene loss or duplication, and insertion of foreign sequences

32
Q

selective value (adaptive value)

A

The relative reproductive success of an allele or genotype as compared to other alleles or genotypes

33
Q

preadaptation

A

The possession of a trait that coincidentally predisposes an organism for survival in an environment different from those encountered in its evolutionary history; may occur because a population carries a huge quantity of genetic variability

34
Q

adaptation

A

And evolutionary process whereby a population becomes better suited to its habitat over many generations

35
Q

Selection

A

A composite of all the forces that cause differential survival and differential reproduction among genetic variance (artificial vs. natural selection); key mechanism of evolution

36
Q

Evolution

A

Genetic changes in populations of organisms through time that lead to differences among them

-Occurs where there is a change in gene frequency within a population over time
-These genetic differences are heritable and can be passed on to the next generation

37
Q

It is in the best interest of the host to possess adaptations that allow it:

A

(1) avoid encountering the parasite
- hosts that behave in a genetically determined way that reduces its probability of
encountering a parasite will be positively selected for
(2) to get rid of the parasite if an encounter has taken place
- hosts whose genetically determined traits allow them to eliminate the parasite
will be positively selected for

38
Q

It is in the best interest of the parasite to possess adaptations that allow it:

A

(1) to encounter the host
- parasites that possess a genetically determined behavioral trait that increases
the probability of encountering the host will be positively selected for
(2) to survive in the host if the encounter has occurred
- parasites whose genetically determined traits allow them to survive the host’s
immune system will be positively selected for

39
Q

Adaptations for Parasite Transmission
Immunological adaptations

A
  1. Absorption of host antigen
    Ex. Schistosoma spp.
  2. Antigenic variation
    Ex. Trypanosoma brucei (VATs), Giardia
  3. Occupation of immunologically privileged sites
    Ex. Leishmania spp., Trypanosoma cruzi, Plasmodium spp.
  4. Disruption of the host’s immune response
    Ex. Entamoeba histolytica
  5. Molecular mimicry
    Ex. Trypanosoma cruzi
  6. Loss or masking of surface antigens
    Ex. Trypanosoma brucei, Entamoeba histolytica, Ancylostomum caninum
40
Q

Adaptations for Parasite Transmission
Behavioral

A
  1. adaptive advantage of parasite behavior
    Ex. Schistosoma mansoni cercariae
    Rats Humans
  2. parasite may alter host behavior
    Ex. Dicrocoelium species
    Cow → Snail → Ant → Cow
41
Q

Adaptations for Parasite Transmission
Life Cycle Adaptations

A
  1. reduction in the extent of the free-living phase of the life cycle
    (this avoids the variable external environment)
  2. behavioral responses to locate favorable environments
  3. responding to chemical stimuli from their host
  4. changing the behavior of the infected intermediate host to increase
    the chances of them being eaten by the final host
  5. infection of secondary and tertiary hosts. This has 4 advantages:
    A. increased reproductive potential, since asexual reproduction can take place in the intermediate host Ex. Digeneans
    B. increases the range of the parasite in space and time
    C. by infecting more than one host species the parasite can survive periods when one host is temporarily scarce
    D. an intermediate host can channel the parasite towards its definitive host since the intermediate host is frequently part of the final host’s food chain
42
Q

Red Queen Hypothesis

A

Originally proposed by Leigh Van Valen (1973)
- metaphor of Alice and the Red Queen from Lewis Carroll’s, Through the Looking Glass
- species have to “run” (evolve) in order to stay in the same place (extant)
- cessation of change may result in extinction
Ex. Parasite-Host Coevolution
- each time the parasite population acquires a new “weapon” (Ex. new antigen), the host population is led to produce a new defense (new antibody, directed at this antigen)
- parasite and host populations are engaged in an “endless” arms race / war

43
Q

Adaptations for Parasite Transmission
Morphological adaptations

A
  1. size- many parasites are larger than their free-living relatives
  2. attachment organs- suckers, hooks & spines, penetration organs, and cysts, etc
  3. loss (regression) of anatomical structure- organs of sense, locomotion, digestion, etc
44
Q

Adaptations for Parasite Transmission
Biochemical adaptations

A
  1. Energy metabolism- catabolic pathways are usually reduced or modified in many parasites
  2. Nutrient uptake- there is an elaboration of transport mechanisms for acquiring monomers / Ex. glucose, amino acids, etc.
  3. Synthetic reactions- synthetic capacities of parasites are reduced when compared with their free-living relatives
45
Q

Adaptations for Parasite Transmission
Reproductive

A
  • produce more eggs and sperm than their free-living relatives do
    1. high reproductive potential
    2. asexual reproduction
    3. hermaphroditism
    4. self-fertilization

Parasitology (4 decks)

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