Final Exam Flashcards
1
Q
Drimtry Ivanovsky
A
- was the first to isolate a virus
- found infectious agents could pass through a chamberland filter
2
Q
chamberland filter
A
made of unglazed porcelain, contain pores that are too small to permit the passage of most bacteria
3
Q
viruses
A
- living organsims, can carry out metabolic processes, maintain homeostasis, reproduce
- considered non-cellular life
4
Q
viruses characteristics
A
- obligatory intracellular parasites
- contain DNA or RNA
- have a protein coat
- some enclosed by an envelope
- some have spikes
5
Q
host range
A
is the spectrum of host cells that the virus can infect
6
Q
viruses that can infect
A
known as bacteriophages (receptor is part of the cell wall) or phages
7
Q
viral host range
A
Determined by specific host attachment sites and cellular factos
8
Q
viral morphology
A
- icosahedral: 20 flat triangles
- helical: capsomeres arranged in helix
- complex: phage
9
Q
Virion
A
a viral particle that consists of nucleic acid and protein (DNA or RNA)
10
Q
capsid
A
protein coat made up of indentical subunits called capsomeres, protects nucleic acid
11
Q
nucleocapsid
A
combination of the nucleic acid and capsid
12
Q
spikes
A
Glycoproteins that are used to attach to a host cells; define the host range of the virus
13
Q
envelope
A
derived from the hosts plasma membrane, composed of lipids, proteins, and carbs
14
Q
viral genome
A
encodes the viruses structural components (capsid proteins), few enzymes
15
Q
viral multiplication
A
- to multiply it must invade a host cell
- once inside the cell that virus hijacks the hosts cell expression machinery
- the cell starts to produce components of the virus
- the viral components are assembled
16
Q
bactierophages
A
viruses that infect bacteria, typically complex morphology
17
Q
bacteriophages replication
A
- lytic phages- ends with lysis and death of the cell
- lysogenic (temperate) phages- ends with host cell remaining alive
18
Q
lytic cycle
A
- Attchement: phage attaches by tail fibers to host cell
- Penetration: phage lysozyme opens cell wall; tail sheath contracts to force tail core and DNA into cell
- Biosynthesis: production of phage DNA and proteins
- Maturation: assembly of phage particles
- release: phage lysozyme breaks cell wall
19
Q
lysogenic cycle
A
- attachment: phage attaches to host’s cell surface
- Penetration: phage injects genetic material into host cell
- integration: phage DNA integrates into host chromosome forming prophage
- replication: prophage replicates
- synthesis: phage DNA and proteins are synthesized using host cell machinery
- Assembly: phage DNA and proteins are assembled to form new viruses
- release: virions are released on lysis of the host cell
20
Q
multiplication of animal viruses
A
- attchment: virus attches to cell membrane
- Penetration: by endocytosis or fusion
- uncoating: by viral or host enzymes
- biosynthesis: production of nucleic acid and proteins
- maturation: nucleic acid and capsid proteins assemble
- release: by budding (enveloped) or rupture
21
Q
animal viruses
A
have attachment sites (spikes), naked animal viruses enter the EU host cell by endocytosis, enveloped viruses enter by fusion with PM
22
Q
uncoating
A
the viral nucleic acid must be released from the capsid, can be done by viral enzymes or host enzymes
23
Q
DNA viruses
A
single stranded DNA viruses, double stranded DNA viruses
24
Q
DNA virus replication
A
- virion attaches to host cell
- virion enter cell and its DNA is uncoated
- A portion of viral DNA is transcribed, producing mRNA that encodes early viral proteins
- viral NDA is replicated and some viral proteins are made
- late translation; capsid proteins are synthesized
- virions mature
- virions released (lysis or budding)
25
RNA viruses
single and double stranded RNA
26
retroviruses
use their viral RNA as a template for DNA, carry out reverse transcription by an reverse transcriptase
27
Multiplication of retrovirus
1. virus enters by fusion between attachment spikes and host cell receptors
2. uncoating releases the two viral RNA genomes and viral enzymes
3. Reverse transcriptase copies viral RNA to produce double stranded DNA
4. new viral DNA is transported into host cell's nucleus where it is intregtaed into hots's chromosomes
5. viral proteins are processed by viral protease, some proteins are moved to host PM
6. mature retrovirus leaves host cell acquiring an envelope and attachment spikes and buds out
28
latent infections
viral genome remains silent in host cell (provirus), can reactivate to cause productive infection
29
pronto-oncogenes
stimulate cell growth and division
30
tumor suppressor
genes inhibit growth division
31
ocogene
proto-oncogene that has been changed to promote uncontrolled growth
32
viroids
small single stranded RNA molecules that are only found in plants and enter through wound sites
33
prions
disease occurs when prion protein becomes abnormal and clumps in the brains, causes brain damage
34
Macroscopic fungi
mushrooms, puffballs, gill fungi
35
Microscopic fingi
yeasts and molds
36
reproductive strategies
1. simple outward growth of existing hyphae
2. Fragmentation: separated piece of mycelium can generate a new colony
3. primary reproductive mode: spore formation
37
yeast cell
unicellular, round oval shape, asexual reproduction (budding or blastconidia formation)
38
hyphae
consists of long filaments of cells joined together
39
dimorphic
some fungi can take either form
40
septa
divide hyphal cells into districts, uni-nucleated, have a continuous cytoplasm
41
Vegetative hypha
the portion of hypha that obtains nutrients
42
aerial hypha
portion of hypha that is concerned with reproduction
43
dimorphic fungi
moldlike forms produce vegetative and aerial hyphae, it is temperature dependent
44
Mycelium
filamentous mass of hyphae
45
condiospores (asexual spores)
uni or multicellular spores that are no enclosed in a sac
46
sporangiospores (asexual spore)
formed within the sac and the end of an aerial hypha
47
sexual spores
result from fusion of the nuclei from two opposite mating strains of the same species
48
saprobes
obtain substrates from dead plants and animals
49
fungi of public health importance
1. most human fungal infection occur through accidental contact
2. allergies caused by fungi
3. opportunistic infections
50
why are respiratory fungal infections becoming more common
1. increased urban development and deforestation
2. climate change
3. increased number of people with weakened immunity
51
endemic fungi
only grow in specific geographical location, causes endemic mycoses
52
Ubiquitous fungi
grow in varied climates and under diverse conditions, some are part of normal flora
53
blastomycosis (chicago disease)
dimorphic endemic fungi, noncommunicable, thrives on decomposing plant matter, produces conidia spores, becomes airborne
54
conccidioides
valley fever, in lungs, develop into sphserules, spherules rupture and release fungal endospores, spread with wind, spores inhaled, noncommunicable
55
histoplasmosis
dimorphic fungus, produces macroconidia spores, spores become airborne with dust or soil, spores inhaled, spores germinate into pathogenic yeast form
56
cryptococcus neoformans
fungus that causes chronic meningitis with gradual onset of symptoms, transmitted through bird droppings
57
broad spectrum drugs
effective against more than one group of bacteria, tetracyclines
58
narrow spectrum drugs
only target a specific group, penicillins
59
Antibacterial drugs: targeting cell wall
Penicillins, cephalosporins
60
antibacterial drugs that target cell membrane
1. polymyxins- narrow spectrum, toxic to kidneys
2. daptomycin
61
polymiyxins
1. target cell membrane
2. interact with membrane phospholipids
3. used to treat severe UTIs
62
Antibacterial drugs that target protein synthesis: aminoglycoside drugs
composed of 1 or more amino sugars and 6-carbon ring, broad antimicrobial spectrum, used to treat bubonic plague and TB
63
Antibacterial drugs that target protein synthesis: tetracylines
broad spectrum: bind to ribosomes, block protein synthesis, can cause tooth discoloration and grastrointestial disruption
64
antibacterial drugs that target folic acid synthesis
sulfonamides or sulfa drugs: first modern antimicrobial, can only be made synthetically, used to treat burns and eye infections
65
antibacterial drugs that target DNA or RNA
fluoroquinolones: broad spectrum, high potency, absorbed in intestine, used against gram-positive organisms
66
Antibiotics and biofilms
antimicrobials are 1000 times less effective to same bacteria in biofilms than when free living
67
fungal infections
most antibacterial drugs act on bacteria and are ineffective against fungi, 4 main groups: polyene antibiotics, azoles, echinocandins, allylamines
68
antiviral agents modes of action
1. barring penetration of the virus into the host cell
2. blocking the replication, transcription, and translation of viral molecules
3. preventing maturation of viral particles
69
intrinsic drug resistance
bacteria must be resistant to any antibiotic that they themselves produce
70
Acquired drug resistance
bacterial resistance to a drug to which they were previously sensitive
71
how does drug resistance develop
1. Resistance through horizontal transfer
2. accounts for the rapid proliferation of drug-resistant species
3. Transposable drug resistance sequences
72
mechanisms of drug resistance 1
1. new enzymes are synthesized
2. Permeability or uptake of the drug into a bacterium is decreased
3. drug is immediately eliminated
73
mechanisms of drug resistance 2
1. binding sites for drug are decreased in a number or affinity
2. an affected metabolic pathway is shut down or alternative pathway is used
74
role antimicrobials
disrupting microbial biota and causing superinfections
75
shotgun approach
using a broad-spectrum antibiotic to treat a suspected infection before the specific pathogen, can potentially lead to an overdose of antibiotics
76
Probiotics
food or supplements that contain live microorganisms intended to maintain to improve the good bacteria in the body
77
Prebiotic
are foods that act as food for human microflora
78
superinfection
beneficial resident species are destroyed through antibiotic therapy
79
microbial control methods
salting foods, smoking food, drying food, burning clothes and corpses
80
Sterilization
Destruction of all microbial life
81
disinfection
destroys most microbial life, reducing contamination on inanimate surfaces
82
antisepsis
called degermation, the same as disinfection, but on living surface
83
decontamination
called sanitation, mechanical removal of most microbes from animate or inanimate surface
84
bacterial endospores
considered the most resistant microbial entities
85
effect of agents on cell wall
damage cell wall, blocking cell wall synthesis, digesting cell wall, breaking down surface of the cell wall
86
how agents affect cell membrane
cell membrane and viral envelope are composed of lipids and proteins, loss of vital molecules, loss of selective permeability
87
surfactants
polar molecules with hydrophilic and hydrophobic regions
88
agents that alter protein function
denaturation of proteins
89
methods of physical control
heat, radiation, filtration, cold
90
thermal death time
shortest length of time required to kill all test microbes at a specified temp
91
thermal death point
lowest temp required to kill all microbes in a sample in 10 minutes
92
dry heat methods
incineration, hot air
93
effects of cold
slows down the activities of most microbes
94
desiccation
dehydration of vegetative cells directly exposed to normal room air
95
lyophilization
combination of freezing and drying
96
osmotic pressure
adding large amounts of salt or sugar to foods creates a hypertonic enviorment
97
high level germicides
kill endospores, sterilants if properly used
98
intermediate level germicides
kill fungal not bacterial spores, resistant to pathogens
99
