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BMB 252 Mol/Cell Bio 2 > Exam 4: Chp 23 - Pathogens and Infection > Flashcards

Exam 4: Chp 23 - Pathogens and Infection Flashcards

(72 cards)

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1
Q

Pathogens

A

are organisms, cells, virus, or prions that cause disease

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2
Q

Microbiota

A

collective of microorganisms that reside in or on an organism

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3
Q

Microbiome

A

combined genomes of the various species of a defined microbiota

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4
Q

Three types of relationships between a microbe and its host

A

1) mutualism
2) commensalism
3) parasitism

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5
Q

Mutualism

A

both organisms benefit

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6
Q

commensalism

A

microbe benefits, but no harm is done to the host

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7
Q

parasitism

A

microbe benefits at the detriment of the host

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8
Q

4 types of pathogens

A

1) primary pathogens
2) opportunistic pathogens
3) facultative pathogens
4) obligate pathogens

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9
Q

Primary pathogens

A

cause overt disease in healthy people

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10
Q

Opportunistic pathogens

A

normal microbes of the flora that can cause disease only if the immune systems are weakened, or if they gain access to a normally sterile part of the body

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11
Q

Facultative pathogens

A

bacteria that replicate in an environmental reservoir and only cause disease if they encounter a host

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12
Q

Obligate pathogens

A

bacteria that can only replicate inside their host

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13
Q

Three shape classifications of bacteria

A

1) spiral
2) sphere
3) rod

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14
Q

Two factors used to classify bacteria

A

shape and gram staining ability

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15
Q

Gram positive bacteria

A

Have thick peptidoglycan cell cells

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16
Q

Gram negative bacteria

A

have thinner peptidoglycan cells walls and outer membrane containing lipopolysaccharide (LPS)

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17
Q

Bacterial appendages

A

flagella and pili

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18
Q

Flagella

A

long bacterial appendage that enables swimming

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19
Q

Pili

A

Short bacterial appendage that allows attachment to surfaces

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20
Q

PAMPS

A

Pathogen associated molecular patterns; includes peptidoglycan and LPS

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21
Q

Virulence genes

A

genes that contribute to an organism’s ability to cause disease

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22
Q

Virulence factors

A

proteins encoded by virulence genes

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23
Q

Pathogenicity islands

A

large clusters of virulence genes on a chromosome

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23
Q

3 mechanisms of horizontal gene transfer

A

1) transformation
2) transduction
3) conjugation

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24
Transformation
naked DNA is taken up by bacteria
25
Transduction
bacteriophages transfer DNA from one bacterium to another
26
Conjugation
plasmid DNA is transferred from a donor to a recipient bacterium
27
How do extracellular bacteria exert affects on host cells?
release toxins that interact with the host cell to ellicit a response that is beneficial to the pathogen
28
What subunits are bacterial toxins typically composed of?
a (enzymatic) and b (binds to host receptor and direct a into host cell cytosol
29
Type III secretion system
injects proteins into a host cell using a needle like appendage
30
Two states of fungi
unicellular yeasts and multicellular molds (transitions between states)
31
What group of organisms have the most elaborate life cycle?
protozoans
32
What is the protozoan lifecycle highly complex?
each stage is specialized for a different tissue and host
33
Function of 3 typical proteins produced by viral genomes
1) to replicate the genome 2) to package and deliver the genome to more host cells 3) to modify the structure or function of the host cell to enhance replication of the virus
34
What of the 6 steps of viral replication
1) entry into the host cell 2) disassembly of the infectious virus particle 3) replication of the viral genome 4) transcription of viral genes and synthesis of viral proteins 5) assembly of viral components into progeny virus particles 6) release of progeny virus
35
Two key types of viruses
RNA and DNA
36
Capsid
protein coat that packages viral genomes
37
nucelocapsid
capsid packaging a viral genome
38
nonenveloped virus
leave cells by lysing them and do not have a membrane
39
enveloped virus
virus buds off the cell's plasma membrane, encapsulating it in a lipid bilayer
40
Why is it difficult to create antiviral drugs?
Because viruses manipulate host cell machinery thus it is hard to target the specifically viral machinery
41
What is the most effective control of viral diseases?
prevention via vaccination
42
5 common tasks for all pathogens
1) gain access to the host 2) reach an appropriate niche 3) avoid host defenses 4) replication 5) exit from the infected host to spread to an uninfected one
43
What three epithelial barriers prevent pathogen infiltration of the host?
1) skin 2) lungs 3) GI tract and bladder
44
How does skin prevent pathogen infiltration of the host?
serves as a physical barrier
45
How do lungs prevent pathogen infiltration of the host?
epithelial cilia sweep things out of the lungs
46
How does the GI tract and bladder prevent pathogen infiltration of the host?
layer of mucus that is periodically flushed
47
2 ways pathogenic bacteria and parasites overcome protective epithelial barriers
1) proteins and protein complexes like pili 2) recognize and bind to cell surface molecules on epithelium
48
Tir
protein that is secreted into host cell and folds into a receptor that then presents on the host cell and receives intimin presented by bacteria
49
Intimin
presented by bacterial cell and received by Tir receptor on host cell (injected by bacteria)
50
First step of a virus entering a host?
must bind to receptors on the surface of the host cell
51
4 ways that viruses enter host cells
1) fusion with the plasma membrane (enveloped viruses) 2) fusion with the membrane after endocytosis 3) pore formation 4) endosomal membrane disruption
52
How do MOST viruses enter the cell?
activate signaling pathways that induce endocytosis
53
What process do bacteria activate to enter a host cell?
phagocytosis
54
2 primary mechanisms bacteria use to induce phagocytosis
1) zipper mechanism 2) trigger mechanism`
55
Zipper mechanism
bacteria express invasion protein that binds to host cell receptor (cell-cell/cell-matrix protein) causing actin polymerization
56
Trigger mechanism
bacteria inject effector proteins into host (using type III secretion system) that induce membrane ruffling via actin polymerization
57
Through what pathway do both the zipper and trigger mechanisms induce actin polymerization
Rho > WASp > Arp 2/3 > actin polymerization
58
What pathway does the trigger mechanism induce actin polymerization besides Rho?
directly
59
Why is parasite invasion of a host cell different from bacterial and viral invasion?
parasites expend their own energy to enter the cell, not manipulate host cell machinery
60
3 paths a pathogen takes after gaining entry to a host cell
1) escape into the cytosol 2) resist fusion with lysosome 3) evolve to survive within the harsh environment of a lysosome
61
Phagolysosome
a pathogen exists within a fusion of lysosome and its original phagosome
62
How are intracellular pathogens able to survive within a host cell?
hijack vesicular transport to establish a niche
63
How do intracellular pathogens acquire envelopes?
evolved a variety of different mechanisms to do so (ex. wrapping via golgi)
64
Autophagy
process by which organelles are surrounded by a double membrane autophagosome that fuses with lysosomes to promote degradation
65
What are 4 ways microbes manipulate the autophagy pathway
1) surface modification of the autophagosome 2) escape using actin-based movement 3) fusion with autophagosome and then release into the extracellular space 4) growing near the autolysosome to utilize nutrient produced during degradation
66
Antigenic variation
ability to change antigens on the surface of a cell
67
How do bacteria and parasites mediate antigenic variation?
DNA rearrangements
68
How do viruses mediate anti-genic variation?
error-prone replication mechanisms that causes viruses to mutate quickly
69
Why do viruses have error-prone replication mechanisms?
reverse transcriptase lacks proofreading activity
70
How does influenza mediate antigenic variation?
genome consisting of 8 strands; if two strands infect the same host they can undergo recombination
71
Three strategies bacteria use to become resistant to antibiotics
1) alter molecular target of the drug so it is no longer sensitive to the drug 2) produce an enzyme that modifies or destroys the drug 3) Prevent the drugs access to the target by pumping it out of the bacteria

BMB 252 Mol/Cell Bio 2 (9 decks)

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