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Chapter 23 Flashcards

Pathogens and Infection (68 cards)

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1
Q

Pathogen

A

Organism, cells, virus, or prions that CAUSE DISEASE

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2
Q

Microbiota

A

The collective of microorganisms that reside in or on an organism

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3
Q

Microbiome

A

The combined genomes of the various species of a defined microbiota

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4
Q

Mutualism

A

Both organisms benefit

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5
Q

Commensalism

A

Microbe benefits, but no harm is done to the host

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6
Q

Parasitism

A

Microbe benefits at the detriment of the host

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7
Q

Primary pathogen

A

Causes overt disease in healthy people

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8
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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9
Q

Facultative pathogens

A

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

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10
Q

Obligate pathogens

A

Bacteria that can only replicate inside their host

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11
Q

Gram +

A

Have thick peptidoglycan

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12
Q

Gram -

A

Have thinner cell walls and has an outer membrane containing LPS

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13
Q

flagella

A

Enable bacteria to swim

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14
Q

pili

A

allows bacteria to attach to surfaces

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15
Q

Virulence genes

A

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

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16
Q

Virulence factors

A

proteins encoded by virulence genes

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17
Q

Pathogenicity islands

A

large clusters of virulence genes on a chromosome

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18
Q

3 mechanisms of Horizontal Gene Transfer

A
  1. Transformation
  2. Transduction
  3. Conjugation
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19
Q

Transformation

A

Naked DNA is taken up by bacteria

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20
Q

Transduction

A

Bacteriophages transfer DNA from one bacterium to another

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21
Q

Conjugation

A

Plasmid DNA is transferred from a donor to recipient bacterium

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22
Q

What are the fungi’s two states?

A

unicellular yeast and multicellular molds

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23
Q

Protozoans life cycle

A

Very complex and depends on where it is located in host

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24
Q

What do viruses depend on for all aspects of viral propagation

A

Host cell machinery

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25
What functions do the 3 viral genomes proteins have?
1. Replicate genome 2. Package and deliver the genome to more host cells 3. Modify the structure or function of the host cell to enhance viral replication
26
Viral replication steps (6)
1. Entry into the host cell 2. Disassembly of the viral genome 3. Replication of the viral genome 4. Transcription of viral genes and synthesis of viral proteins 5. Assembly of these viral components into viral proteins 6. Release of progeny virions
27
Nucleocapsid
Capsid packaged with the viral genome
28
Non-enveloped viruses leave the cell...
By lysing it
29
Enveloped viruses are...
encapsulated within a lipid bilayer as the virus buds off from the plasma membrane
30
All pathogens share common task (5)
1. They must gain access to the host 2. Reach an appropriate niche 3. Avoid host defenses 4. Replicate 5. Exit from the infected host to spread to an uninfected one
31
Skin
Epithelial barrier
32
Lung
Has epithelial cells with cilia that sweep things upwards and out of lunges
33
GI tract and bladder
Have layers of mucus that are periodically flushed to help remove any pathogens that may have infiltrated the area
34
Do extracellular pathogens enter host cells?
No
35
Type III Secretion System
A needle-like structure that injects bacterial proteins directly into host cells
36
Tir function
Tir is injected into the host cell, inserts into the membrane, and acts as a receptor for the bacterial protein intimin
37
Intimin
Bacterial surface protein that binds to Tir on the host membrane
38
Do intracellular pathogens enter host cells
YEs
39
Are viruses intracellular or extracellular?
All are intracellular pathogens
40
How do viruses initially interact with host cells?
They bind to specific virus receptors on the host cell surface
41
What happens after a virus binds to a host cell receptor?
Triggers intracellular signaling pathway that lead to endocytosis
42
Enveloped virus entry into host cell
Fusion of their envelope with the host's lipid bilayer Then releasing their genome
43
Nonenveloped virus genome into host cell
Undergo conformational change to... 1. Form a pore 2. Cause endosomal membrane to rupture
44
How do intracellular bacteria pathogen enter the cell
Through phagocytosis
45
What are the 2 mechanisms to induce phagocytosis by host cell?
Zipper Mechanism and Trigger Mechanism Both of which will cause actin polymerization
46
Zipper Mechanism of Phagocytosis
Bac. expresses invasin which binds to host-cell receptors
47
Trigger Mechanism of Phagocytosis
Bac. inject a set of effector molecules into the host which induces membrane ruffling
48
What does parasite infections require?
Energy expenditure from the parasite
49
After entry into the cell pathogens can.....(3)
Escape into the cytosol Modify the endosome so it doesn't fuse with lysosome Evolve to survive in the harsh lysosomal environment
50
What do viruses and bacteria use for intracellular movement
Host - cell cytoskeleton
51
Pathogens escape into the cytosol instead of remaining in compartment to
Reach specific areas of host and avoid degradation
52
What is the main way pathogens manipulate the cytoskeleton for movement?
Actin polymerization to push them forward
53
What part of the cytoskeleton do some viruses use as a highway through the host?
Microtubules
54
What motor protein moves the virus towards the minus end of microtubles?
Dynein
55
What motor protein typically moves cargo to the plus end of microtubles?
Kinesin
56
Neurotropic alphaherpesviruses
Infect peripheral nerve cells from neighboring epithelial cells in the skin
57
Autophagy
Process by which organelles are surrounded by a double - membrane autophagosome that fuses with lysosomes to promote degradation
58
Antigenic variation
Ability to change antigens on the surface of a cell
59
Whay is antigenic variation beneficial
Organisms can evade the immune system if it changes the antigens expressed on its surface
60
How do bacteria and parasites achieve antigenic variation?
DNA rearrangements
61
How do viruses achieve antigenic variation?
Via error - prone replication
62
Retroviral genome mutation rate
One mutation every replication cycle
63
Why are viruses so error - prone?
Reverse transcriptase lacks proofreading activity
64
Why is the flu vaccine updated annually?
Reassortment of influenza virus genomes when 2 strains infect the same cell
65
Bactericidal antibiotics
Kill bacteria
66
Bacteriostatic antibiotics
inhibit bacterial growth without killing them
67
Selective toxicity
Targeting bacterial functions without harming host cells
68
3 strategies for bacteria to continuously evolve and become resistant to antibiotics
1. Alter molecular target of the drug so its 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 (12 decks)

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