Micro exam 2 Flashcards
1
Q
peptidoglycan
A
backbone of cell wall in prokaryotes, composed of repeating sugars NAG and NAM
2
Q
assembly of cell wall
A
NAG and NAM repeat, assembled by enzymes transglycosylae, tarnspeptidase, polymerase, and hydrolase, how cell wall is made can be used for better antibiotics
3
Q
Cytoplasmic Phase
A
NAG/NAM are built in cytoplasm and are constantly replenished, particularly when dividing
4
Q
Membrane Associated Phase
A
enzymes link NAG and NAM with lipids to form peptidoglycan
5
Q
Extracytoplasmic phase
A
new peptidoglycan moves from inside of cell towards outside, incorporating into cell wall
6
Q
teichoic acid
A
in gram positive bacterial cells in addition to many layers of peptidoglycan (makes the gram positive cell have an overall negative charge)
7
Q
Gram positive cell walls
A
very thick wall of peptidoglycan covering the plasma membrane with various lipoteichoic acid and wall associated proteins
8
Q
Gram negative cell walls
A
outer membrane with porins with lipopolysaccharide (O-polysaccharide and lipid A), then a periplasmic space with lipoproteins, a small layer of peptidoglycan and then the plasma membrane
9
Q
lipopolysaccharide layer
A
outer membrane, composed of lipids, proteins
10
Q
Porins
A
proteins contain channels that vary in size and specificity and they are responsible for the passage of molecules and ions into and ort of the gram negative cell
11
Q
translocation protein systems
A
move substances out of the cell
12
Q
Periplasmic space
A
space between the plasma membrane and the other membrane, filled with gel-like material and contains variety of proteins secreted by the cell
13
Q
M protien
A
virulence factor in gram positive organisms, protrudes from cell wall, required for infection, antibodies can inhibit it
14
Q
Mycolic acid
A
in gram positive organisms, synthesizes waxy lipid known as mycolic acid that makes organisms resistant to antibiotics/disinfectants/ect
15
Q
Lipid A
A
gram negative bacteria, anchors the LPS portion of the outer membrane to phospholipid bilayer, releases endotoxins
16
Q
O polysaccharides
A
gram negative, carbohydrate chains that are part of the outer membrane located on the side of the membrane that faces the extracellular fluids
17
Q
structures outside of bacterial cell in adherence
A
glcocalyx, fimbraie, and pili
18
Q
structures outside of bacterial cell in movement
A
flagella, axial filament, and pilli
19
Q
Glycocalyx
A
sticky substance on surface of cells made of polysaccharides and polypeptides, many is known as cell layer, and if adhered tightly is known as capsule
20
Q
slime layer
A
dental decay, permits organisms to adhere to surface and then many organisms adhere to one another, form of glycolyx
21
Q
The capsule
A
form of glycocalyx, required for infection, inhibits phagocytosis
22
Q
Fimbriae and Pilli
A
cell wall components involved in adherence, composed of pilin protein, pili also used in transfer of genetic material through conjugation
23
Q
immune escape
A
ability to evade a host immune response
24
Q
phase variation
A
number of pilli decreases after initial infection, taking away target for antibodies
25
antigenic variation (post-translational modification)
change or mask the structure of pilli so that antibodies no longer recognize the bacteria invaders
26
S pilli
secreted fragments of pilli that bind to antibody molecules and inactivate them
27
axial filaments
flagellum like structures that wrap around bacterial cell and give it mobility, often referred to as endoflagella
28
flagella
long structure that extends far beyond the cell wall, used for motility and is a classic example of the relationship between structure and function, allow bacteria to move rapidly from one location to another
29
structure of flagella
filament (made of flagellin), hook (links filament to basal body), basal body(rod that has rings strategically fastened to it
30
Monotrichous
the most common form of flagellae, in which the barcterium has one flagellum located at one end of the cell
31
amphitrichous
in which the bacterium has two flagella, one at end of each cell
32
Lophotrichous
in which the bacterium has two or more flagella located at the same end of the cell
33
Perltrichous
another form in which the entire cell is surrounded by flagella
34
Plasma membrane
selective permeability, the membrane is made of hydrophillic (outside heads) and hydrophobic (inner layer) molecules, provides barriers between inside and outside of cell
35
integral proteins
fully penetrate the plasma membrane and in some cases contain a pore that connects the interior of the cell to the extremal environment
36
Osmosis
molecules can move across cell membrae "water chases concentration"
37
plasmolysis
cell loses water and shrivels up, hypotonic
38
osmotic lysis
water enters the cell causing cell to expand and eventually lyse , hypertonic
39
isotonic environment
solute concentrations inside and outside the cell are essentially equal
40
passive transport
simple diffusion and facillitated diffusion
41
facilitated diffusion
molecules are brought across the plasma membrane by carrier molecules (permeases) binding of solute changes shape of protien
42
active transport
the carrying of solute either into or out of a cell against the concentration gradient requires expenditure of ATP and uses specific carrier proteins found in plasma membrane
43
Efflux pumping
proteins are part of "super family of transporters" "revolving door" mechanism in which membrane pumps bring in certain molecules and expel others at the same time
44
ABC transport system
molecule transported forms a complex with binding protien on the outside of the plasma membrane
45
group translocation
unique to bacteria, want to stay in ex) glucose is transformed using phosphotransferase enzyme to glucose-6-phosphate so it can no longer move across cell membrane
46
secretion
involves moving substances from the inside of the cell to the extracellular fluid. secretion involves several plasma membrane proteins that act in a specific sequence
47
Nuclear region
region that is most discernable supercoiled and associated with specific positively charged proteins that stabilize it
48
inclusion bodies
membrane enclosed organelles used to stored materials
49
metachromatic granules
store phosphates in inclusion bodies
50
physical requirements for bacteria growth
temperature, pH, osmotic pressure
51
psychrophiles
bacteria that grow at cold temperatures (0-15 C)
52
Psychotrophs
subset of psychophiles, bacteria that grow best between 20-30C
53
Mesophiles
bacteria that grow best at moderate temperatures, 25-40C, most common types of bacteria and human pathogens
54
Thermophiles
bacteria that grow only at temperatures above 45C, extreme thermophiles if above 80C
55
minimum growth temperature
lowest temperature at which an organism grows
56
optimal growth temperature
the temperature at which the highest rate of growth occurs
57
acidophiles
bacteria that grow at extremely low pH values
58
osmotic pressure
pressure exerted on bacteria by their surroundings, can affect bacterial growth
59
halophiles
bacteria that love being in a high salt environment. Obligate require high salt concentrations, facultative can live with or without it and extreme can grow in the presence of very high salt levels
60
what are the two ways bacteria obtain carbon?
the breakdown of preexisting molecules that contain carbon
atoms, which are then used for construction of new molecules. This
“recycling” process is very common in biological systems, and organisms
that use it are referred to as chemoheterotrophs. (pathogenic bacteria)
CO2 molecules,
and these organisms are referred to as chemoautotrophs.
61
Nitrogen
required for making bacterial amino acids and nucleic acids
62
Sulfur
required for making some bacterial amino acids
63
Phosphorous
required for making bacterial nucleic acids, membrane phospholipid bilayer, and ATP
64
Potassium, magnesium, calcium
required for functioning of certain bacterial enzymes
65
iron
required for bacterial metabolism
66
aerobes
bacteria that require oxygen
67
faculatative aerobes
can grow with or without oxygen
67
superoxide dimutase
convert free radical oxygen into molecular oxygen and peroxide, then uses catalase to convert hydrogen peroxide to water and oxygen
68
catalase
converts hydrogen peroxide to water and oxygen
69
aerotolerant bacteria
can grow in the presence of oxygen but do not use it in metabolism
69
peroxidase
convert hydrogen peroxide to water
69
microaerophiles
aerobic bacteria but require only low levels of oxygen for growth
70
Sodium thioglycolate
This medium forms an oxygen
gradient such that the farther into the medium we go, the less oxygen
there is. When bacteria with different oxygen requirements are compared
using this medium (Figure 10.6), obligate anaerobes will always grow in
the area of the tube where oxygen is absent, whereas obligate aerobes
grow only where the oxygen concentration is highest. Facultative anaerobes,
which can grow either with or without oxygen, grow throughout
the sodium thioglycolate medium even though the oxygen concentration
decreases steadily from top to bottom of the tube.
71
GasPak Jar
incubation jar totally devoid of oxygen, only obligate and facultative anaerobes can grow in it
72
fastidious bacterium
slow growing, require a large number of growth factors
73
chemically defined growth medium
chemical composition is precisely known
74
Complex media
complex media contain not
only numerous ingredients of known chemical composition but also
digested proteins and extracts derived from plants or meat. Such media
are referred to as complex because the exact chemical composition of
these digests and extracts is not known.
75
nutrient broth vs solid
both complex media, broth in liquid form, solid is media with agar added
76
selective media
one that contains ingrediants that prohibit the growth of some organisms while fostering the growth of others
77
differential medium
contains ingredients that can differentiate between organisms
78
MacConkey medium
culture and differentiation of bacteria based on their ability to ferment lactose, lactose fermenters form red to pink colonies, non fermenters form colorless or transparent colonies
79
Eosin methylene blue (EMB) agar
isolation, culture, and differentiation of gram-negative bacteria. Lactose fermenting bacteria form green metallic sheen, non fermenting bacteria form colorless or light purple colonies
80
Triple sugar Iron agar
Differentiation of
Gram-negative
bacteria on the basis
of their fermentation
of glucose, sucrose,
and lactose and on
their production of
H2S gas
Red slant/red butt, no
fermentation; yellow slant/
red butt, glucose fermentation;
yellow slant/yellow butt, glucose
and lactose fermentation; butt
turns black, H2S produced
81
Blood agar
Culture of fastidious
bacteria and
differentiation of
hemolytic bacteria
Partial digestion of blood, alpha
hemolysis; complete digestion
of blood, beta hemolysis; no
digestion of blood, gamma
hemolysis
82
Mannitol Salt agar (MSA)
selective/differential medium that is useful for identifying Gram-positive organisms. Uses high salt concentration to select for Staphylococcus species while inhibiting
the growth of other bacteria. In addition to this selection, the mannitol
sugar in MSA permits differentiation between species of Staphylococcus.
83
Generation time
time interval between divisions of bacteria (bacteria divide using binary fission)
84
lag phase
stage of bacterial growth the bacteria are adjusting to their environment
and may have to synthesize enzymes to utilize the nutrients available
in the environment. In this phase, little if any binary fission occurs, indicated
by the fact that the growth curve is horizontal
85
Log phase
the number of bacteria doubles and increases exponentially and will have reached the constant
minimum generation time. This level of growth can be sustained only
while environmental conditions remain favorable and, more importantly,
only if an adequate supply of nutrients remains available
86
Stationary phase of ggrowth
the phase in which
the number of cells dying is essentially equal to the number being produced
through cell division. This phase is relatively short because it is
predicated on the availability of nutrients, which continue to disappear
as the growth curve shifts to the last phase.
87
death phase
represents
a continuous decline in the number of dividing cells. This decline
is caused by exhaustion of the nutrient supply as well as collapse of the
environment due to the build-up of toxic waste materials
88
DNA structure
deoxyribonucleic acid, double stranded helical model made of nucleotides (phosphate and sugar with deoxyribose backbone), antiparallel (3'->5' and reverse)
89
purines
adenine and guanin, large double ring structures
90
pyrimidines
thymine and cytosine, single ring structures
91
DNA pairings
adenine with thymine and cytosine with guanine (AT Genetics Class)
92
structure of RNA
RNA contains the sugar ribose rather than deoxyribose.
* The bases in RNA are adenine, cytosine, guanine, and uracil, and
the base pairings are adenine with uracil, cytosine with guanine.
* RNA is usually found in a single-stranded form. However, RNA can
fold on itself and form areas that are in a double-stranded form (see
the discussion below).
93
messenger RNA
containing information derived from DNA that is used for construction of proteins
94
Transfer RNA
carries amino acids to the ribosome where protein is being constructed
95
ribosomal rna rRNA
helps in maintaining the proper shape of the ribosome and the orientation of the protein under construction
96
Supercoiling
helix twists around itself, before strands can be unwound and separated for replication and transcription, topoisomerase does unwinding
97
helicase
once enzyme is relaxed from supercoiling by topoisomerase, helicase unwinds and separates the chains
98
Primer:template junction
Once the double-stranded DNA has
been unwound, each unwound single DNA strand is called a template.
A portion of this template is then paired with a short segment of RNA
called a primer.
gives the DNA polymerase a place to which the next base can be attached
99
DNA polymerase
enzyme, uses primer:junction as a guide and then takes any of the bases and binds them, can bind many bases at onetime, proofreads
100
exonuclease
enzymes that attack the open ends of molecules, proofread on growing end of 3', strongly attracted to bases that are improperly added and degrades them
101
replication fork
where in DNA double helix replication is occuring, and the double helix is being unwound and the strands are being separated from eachother,
102
leading strand
the 3' DNA strand which has an addition onto it's 3' end polymerase can add bases and moves towards the fork
103
lagging strand
the 5' DNA strand which is moving away from the fork, necessitates replicating the lagging strand in pieces AKA Okazaki fragments
104
primase
can synthesize RNA without a 3' end being present (this synthesis can occur at any place along the DNA sequence). As the replication fork moves, the lagging strand of DNA elongates, and a primase molecule attaches to the strand and synthesizes a small piece of
RNA. This RNA becomes the primer part of the primer:template junction.
104
DNA ligase
the ends of DNA pieces are linked together after RNAaseH removes primer
104
RNAaseH
enzyme that removes the primer RNA the dap that results from the missing primer is filled by DNA polymerase
105
origin of replication
location of Initiation of DNA replication in bacteria begins at a specific spot on the
chromosome
106
replicator sequence
a specific set of DNA sequences that includes a long
string of A-T base pairs. easily opened because less H bonds
107
Degenerate
only 20 amino acids are used to make all the proteins found in all organisms, minimizes the effect of mutations
108
wobble hypothesis
francis crick, states that point mutations are less likely to cause harm due to degenerate feature of codons
109
Stop codons
end of the construction of a protein, UAA, UAG, UGA
110
reading frame
place between initiation/start codon and the end codon, determines how proteins are constructed
111
transcription
construction of RNA from a DNA template
112
translation
construction of protein by using RNA instruction
113
differences between RNA transcriptction and DNA replication
* RNA synthesis does not require a primer:template junction.
* RNA does not remain base-paired to the DNA template once transcription
is complete.
* Unlike DNA polymerase, RNA polymerase is a poor proofreader.
This makes RNA synthesis less accurate than DNA replication.
* Transcription copies only certain portions of a DNA strand, whereas
replication copies all of it.
114
process of transcription
initiation (promoter binds to polymerase)
elongation (RNA polymerase unwinds DNA, adds bases to the growing end of the RNA and closes the DNA strand)
Termination (when the
polymerase reaches a segment of the DNA that signals the end of the
required RNA segment it detaches from the DNA)
115
What types of DNA are used in translation?
all three types: mRNA, tRNA, rRNA
116
messenger RNA in translation
proton coding region of mRNA includes and open reading frame (ORF) which has a start and top codon, mRNA binds to frame and then recruit a ribosome through complimentary base pairing.
117
transfer RNA in translation
tRNA functions as adapters between mRNA attached to a ribosome and the amino acids being added to the growing protein chain, each tRNA attaches to an amino acid and a specific codon, cloverleaf structure
118
anticodon loop
part of tRNA clover structure, is the loop farthest from the arm and is where codon recognition occurs. The whole region of the cloverleaf is the anticodon region
119
aminoacyl-tRNA synthetases
amino acid specific (20 different enzymes)
aids in the attaching an amino acid to tRNA is a two-step process. Step one is
coupling of the amino acid to AMP. The second step is transfer of the
amino acid to the 3' end of the tRNA, low error rate
120
large subunit ribosome
responsible for peptide bond formation
121
small subunit ribosome
contains the decoding center where tRNA bonds to the mRNA (where codon-anticodon recognition occurs)
122
polyribosome
during translation more than one ribosome can attach to the same mRNA molecule
123
peptidyl transferase reaction
the reaction that bonds each amino acid being added to the growing peptide chain in translation
124
3 binding sites for tRNA
a site is for tRNA carrying a single amino acid, P site is for peptidyl-tRNA, which is holding on to the growing peptide chain, and the
E site is for tRNA that is in the process of exiting from the ribosome.
125
3 stages of translation
initiation, elongation, termination
126
translation initiation
1) recruitment of the
ribosome to the mRNA to form what is referred to as the translational
apparatus, (2) placement of a methionine tRNA and its amino acid on the
P site (note that this first tRNA does not go to the A site first), (3) precise
positioning of the ribosome over the mRNA start codon (establishes open reading frame)
127
translation elongation
aminoacyl-tRNA binds to A site, peptide bond formation, translocation, proofreading between mRNA and tRNA
128
translation termination
translation continues until a stop codon enters the A site, then peptide chain released from ribosome and subunits of ribosomes disassociate from mRNA
129
constitutive gene
a gene that is always on/expressed , regulated by positive regulation (proteins boost production) or negative regulation (proteins repress production)
130
operator site
region of DNA strand where the regulatory proteins bind
131
lac operon
lactose operon, positive regulation, set of genes that enable bacteria to use sugar lactose, inducible genes (off but can be turned on), turned on using lac activator CAP, repression is always on but lac operon activates if environment does not contain glucose
132
tryptophan production
feeback inhibition that occurs post transcription, tryptophan is made until it accumulates in excess and then opresses it's own synthesis by the excess bying to a repressor protein which changes the chape of the geses and prevents further synthesis
133
silent mutation
point mutation, single base change in DNA with no change in ammino acid, causes no effect in the protein
134
missense mutation
point mutation, change in DNA sequence that results in a change in the amino acid sequence, causes a change in the protein that can cause significant alteration of protein function
135
nonsense mutation
change in DNA sequence that creates a premature stop codon, produces truncated and non-functional protein
136
frame shift mutation
deletion or insertion of one or more bases into the DNA sequence, changes the entire sequence of codons and greatly alters the amino acid sequence. transposition is a form of insertion that can cause a frameshift and change the genetic makeup of bacterium
137
transposons
jumping DNA, generates much of the frameshift mutations
138
suppressor mutations
reverse the primary mutation and reestablish the construction of a functional protein
139
mutagens
chemicals that cause DNA mutation
ex) radiation
140
nucleotide excision
looks for distortion of DNA double helix and removes strands of DNA near the mutation and allows DNA polymerase and ligase to fix
141
base excision
enzyme specific, enzyme flips out base and corrects it
142
photoreactivation
unlinks the damaging thymine dimers formed when DNA is exposed to UV radiation, uses photolyase
143
recombination
bacteria "shuffle" their genes using transformation, transduction, conjugation, and transposition
144
transposition
genetic elements
called transposons move from one place on a bacterial chromosome to
another, random so can be good or bad, most common form of mutation
145
transformation
naked DNA released after cell death is taken up y a bacteria cell and recombines with that cell's DNA
146
griffith experiment
shows transformation
a) living bacteria into mice and mouse dies
b) living nonencapsulated bacteria into mouse and mouse lives
c) heat killed encapsulated bacteria into mouse and mouse lives, living nonencapsulated and heat-killed encapsulated bacteria injected into mouse and mouse dies
**concludes that the bacteria had transformed to gain genes for a capsule
147
generalized transduction
DNase cleaves DNA and is randomly carried into viral particles, recombines with newly infected host cell DNA in the recipients chromosome
148
specialized transduction
the phage DNA initially becomes incorporated
into an infected cell’s chromosome and is called a prophage, excise from chromosome and join acterial chromosome "donor DNA"
149
conjugation
direct contact between donor and recipient cells, plasmid DNA travels through pilus between DNA
150
HFR
In an Hfr cell, the host chromosome has a prophage integrated into it. When this cell is
involved in conjugation it can transfer host cell DNA sequences that are adjacent to the
integrated prophage
151
dissimilation plasmids
contain genetic information that allows organisms to become more resistant to disinfectants and more able to adapt to otherwise destructive environments
152
obligate intercellular parasites
viruses, cannot live outside of a cellular host (multiply and produce new viral particles)
153
capsid
protein coat that encloses the genetic material of viruses, may also wrap in envelope of lipids or host membranes
154
virion
a single viral particle
must hold up to environment and be able to shed capsid once entering host cell
155
capsomere
protein subunits forming capsid
156
capsid
protein coat, protein shell surrounding nucleic acid
157
nucleocapsid
nucleic acid plus capsid
158
envelope
viral membrane, phospholipid bilayer with embedded glycoproteins surrounding capsid in enveloped virus
159
viron
viral particle, complete infectious viral structure: nucleic acid plus capsid for non-enveloped virus, nucleic acid plus capsid plus envelope for enveloped virus
160
helical viruses
bonding of capsomeres determine symmetry, helical have a rod shape or a filamentous/curve shape, segmented RNA ex)influenza
161
nucleoproteins
in helical viruses each segment of RNA is enclosed in a helical capsid held in place by multiple proteins called nucleoproteins
162
matrix protein
within helical viruses, second layer of protein just inside the envelope
163
Icosahedral
type of shape of DNA, based on 20 triangle faces of capsid, has 12 points, ex) polio (simple)
164
simple icosahedral virus
the capsid is made of a large number of identical 3-polypeptide capsomeres ex) polio
165
complex icosahedra viruses
icosahedral virus with additional proteins and lipids surrounding the capsid ex) herpes
166
tegument
protein layer located between capsid and envelope in icosahedral viruses
167
complex viruses
viruses that do not have either helical or icosahedral symmetry ex) pox virus
168
genomic packing
There are three ways in which viruses package their nucleic acid: (1) directly in the capsid (simplest, attachment occurs at inner side of protein coat) (2) enclosed in specialized proteins (nucleic acid-binding proteins, very stable) (3) enclosed in proteins from the host cell
169
bacteriophages
viruses that infect bacteria, helps provide information on infection cycle
170
lytic infection cycle
seen in animal virus, During the infection cycle of many viruses, the host cell is used to produce more virions, and when the host cell is completely filled with new
virions the host cell simply bursts. This is called lysis
171
lysogenic cycle
viral genome becomes incorporated into the host
cell’s DNA and can remain this way for an extended period, causes latent infection
172
latent infection
no new virus made and no increase in infection, when to leave latency and become lytic is based on health of host cell
173
steps of lytic infection
attachment (virion binds to specific receptors on host cell), penetration (may conformationally change capsomere), uncoating (simple uncoating at plasma membrane or uncoating within endosomes or uncoating at nuclear membrane), biosynthesis (synthesis of new viral components as well as new viral genomes), maturation(movement of newly made viral components to specific sites in the host cell and assembly of new virions), and release (lysis or budding off from the host cell)
174
lipid rafts
specific areas of host membrane, rich in cholesterol, fatty acids, and lipids, which make them more densely packed for stable attachment
175
endosome
membrane encloses virion to form a vesicle, acidic environment that helps begin uncoating of virion, then fuses with lysosomes to complete uncoating
176
compartmentalization
In this process, DNA or RNA synthesis of viral genomes as well as synthesis of the new capsids and other viral proteins occurs in specific locations of the host cell. After synthesis, these components are finally moved to other specialized sites for final assembly of the intact virions.
177
reverse transcriptase
can convert RNA into DNA, must penetrate the double membrane for infection to occur, uses import pathways
178
double-stranded DNA (dsDNA) viruses
mRNA required to make viral proteins can be produced by transcribing one stand of the viral DNA, uses either host or viral RNA polymerase molecules for RNA synthesis
179
Single-stranded DNA (ssDNA) viruses
DRN strand must be transcribed to RNA but mRNA cannot be transcribed from single-stranded DNA so 1st strand is used to make second strand which is then used as a template for new viral genomes
180
DNA replication in latent viruses
latent virus incorporates it's genome with host chromosomes, does not need maximal production of viral genomes, only a small number of viral gens replicate at a different location than in lytic
181
viral transcription
newly made viral DNA molecule acts as a template for the creation of viral mRNA, preformed by host's RNA polymerase, in dsDNA viruses transcription begins as soon as it reaches host nucleus, in ssDNA viruses the single DNA strands must first be converted to double to serve as transcription templates, very high rate of transcription but also high regulation
182
double stranded RNA viruses
Double-stranded RNA virus
genomes contain both a (+) and a (–) strand. During infection, the (–) strand
is first copied into mRNA by a viral RNA polymerase to produce viral proteins.
This newly synthesized strand is then used as a template to make a doublestranded
genome, which will be placed into new virions
183
+ single stranded RNA viruses
the (+) strand
is essentially already mRNA and as such it can be directly translated into
viral proteins by the host cell’s ribosomes. Genome replication takes two
steps. First the (+) strand is copied into a (–) strand. Then this (–) strand
is used as a template to produce more (+) strand genomes to place into
new virions
184
- single stranded RNA virus
(–) strand cannot be
directly used as mRNA. Therefore, it must first be copied into a (+) strand
by viral RNA polymerase, which is brought in with the virus. This (+) strand
copy is mRNA and can be used for the synthesis of viral proteins. The production
of genomes for new virions goes through a two-step sequence
in which the (–) strand is copied to a (+) strand and this (+) strand is then
used as the template for new (–) strand genomes that are packaged into
new virions
185
intracellular trafficking
movement of newly made viral components to specific sites in the host cell, done through a series of membrane-enclosed compartments and vesicles using ER and golgi apparatus
186
assembly of non-enveloped viruses
* Formation of structural subunits for the capsid
* Assembly of the capsid
* Association of viral genome within the capsid
187
assembly of enveloped virus
* Formation of structural subunits for the capsid
* Assembly of the capsid
* Association of viral genome within the capsid
* Assembly of viral envelope glycoproteins
188
concerted assembly
the virion is assembled while the viral genome is being synthesized
189
sequential assembly
the viral genome is inserted into already-formed capsids. This latter type of assembly requires a mechanism in which the genome can be pushed or pulled into the capsid. It also requires a portal of entry into the capsid. higher rate of error
190
budding from plasma membrane
bud formation, bud growth, fusion of the bud
membrane, and separation from the host.
191
synctia
a possible way viruses spread, multinucleate mases formed by fusion of many infected cells
192
acute vs persistent viral infections
acute: rapid and self-limiting
persistent: long term ex)latent, or slow/transforming infections
193
cytopathic virus
kill their host cells rapidly to yield the maximum number of virions for continuation of the infections
194
non-cytopathic viruses
produce virions but do not kill host cells
195
antigenic variation
Changes in virion structure. host can be reinfected because they use amino acid substitutions to change the protein configuration to a form that the adaptive response has not "seen" and therefore cannot respond to
196
antigenic drift
slight change in the virion structure, resulting from mutations, occurs after the infection has begun
197
antigenic shift
major changes in the structure of the virion as a result of the acquisition of new genes either from co-infection or through recombination events
198
characters of latent infections
* Absence of a productive infection, in other words, no large-scale production of virions
* Reduced or absent host immune response
* Persistence of an intact viral genome so that productive infections can occur later
ex)shingles and herpes warts
199
susceptibility
the host cell must have the appropriate receptor for viral attachmentp
200
permissiveness
the host cell contains gene products used y the virus for a successful infection
201
site of entry
where the virus enters the body
respiratory tract (most common), digestive tract (common but hostile due to stomach, infected by durable and resistant viruses), urogenital tract (STDs, low defense, often lifelong), eyes (little rate of infection due to constant flushing of eye), skin (barrier must be broken, often insect carried)
202
locations for dissemination of viruses
nervous system (infect through neurons, get to brain and spinal cord), organs such as liver spleen and bone marrow (reaches blood and then makes into vessels and tissues)
203
hematogenous dissemination
virus using bloodstream as best route for dissemination
204
active viremia
virions replicate in the blood
205
zoonotic diseases
diseases that have perpetuation of the infection by transmission from other animals to humans
206
iatrogenic transmission
viral transmission facilitated by poor techniques employed by healthcare workers
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transmission via epidermis
skin rashes
macular lesions (red spots on skin)
papules (small solid elevated lesions)
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virulence
capacity of an infectious organism to cause disease
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attenuated visuses
non virulent, do not cause disease
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PD50
paralytic dose 50%, indicates how much virus is needed to paralyze 50% of infected individuals
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susceptible vs immune hosts
susceptible hosts can be infected and transmit the disease
immune hosts can't be infected or will not transmit the disease
making more a population immune through either infection or vaccination creates herd immunity
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live attenuated vaccine
made up of intact viral particles and have been rendered non-infectious through some form of chemical treatment
ex) pollio drop, measles mumps and rubella (MMR)
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inactivated vaccine
aka killed vaccine, composed of a virus that is either dead or non-infectious, safer than live attenuated
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subunit vaccine
composed of immunogenic parts of the virus and is usually derived through the use of genetic engineering and recumbent DNA techniques, safest type, ex) covid vaccines
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active immunization
antigen representing the infectious agent is administered and causes the onset of an immune response
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passive immunization
already-formed anti-viral product such as antibody
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two groups of parasites
protozoans (microscopic single-celled eukaryotes)
helminths (multicellular worms with differentiated tissues and complex organ systems)
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how are parasitic protozoans classified?
by their method of locomotion, bodies are broken into endoplasm (nutrition and metabolism) and ectoplasm (movement)
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Rhizopods
amoebas, most simple, free living protozoans, form commensal relationships in the human intestine
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Cilliates
move through the use of cilia and are rarely parasitic
flagellates are parasitic organisms
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Sporozoa
cause malaria, asexual and sexual reproduction during infection cycle
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schizogony
cycle of simple fission in reproduction of parasites, followed by a sexual reproduction phase called gametogony
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general characteristics of a helminth
worms
bilaterally symmetrical
covered in acellular cuticle as outer layer
differentiated organs including nervous, excretory, and reproductive
no circulatory system
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Nematodes
Roundworms
cylindrical body and alimentary canal from mouth and anus, separate sexes, 2 types: GI tract nematodes and blood/tissue nematodes
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cestode
tapeworm
head with segmented body (proglottids), hermaphroditic, no alimentary (digestive) tract, typically one host per fife cycle
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trematodes
flukes
leaf-shaped with oral and ventral suckers, hermaphroditic, blind pocket digestive, two intermediate hosts
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definitive host
parasitic host in which asexual reproduction occurs
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intermediate host
parasitic host in which sexual development occurs
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malaria
plasmodium species of sporozoan, parasitic infection of human red blood cells
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life cycle of plasmodium (sexual)
mosquito ingests plasmodium gametocytes from blood, when fertilized forms oocyst, which inside has thousands or sporozoites and then the cyst ruptures the sporozoites fill mosquito body
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life cycle of plasmodium (asexual)
sporozoites transferred from mosquito when biting human, find way to liver and attach to hepatocyte, asexually reproduce and from daughter cells called merozoites, these rupture releasing merozoites and enter ring stage where merozoits attach to specific receptors on red blood cells
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pathognesis of malaria
fever, anemia (malaria destroys red blood cells), circulatory changes (hypotension), incubation to onset is 2 weeks
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malarial paroxysm
cycle of the malaria disease, cold and hot stages
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life cycle of toxoplasma
begins in intestine of cat, trophozoite for of parasite enters cells and becomes merozoites, causes epithelial cells to rupture and release parasite into fecal matter for 2-3 weeks, enter macrophages in hosts blood and travel to all organs which can lead to death of host cells
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amebiasis
diseases caused by rhizopods, found in trophozite form or cyst form, dwell in colon and cause diahrehha, infection caused by fecal oral route where cyst passes through stomach degrades in small intestine and releases trophozoites which repeat the process
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flagellates diseases
trichiniasis (STD, vaginitis, has axostyle microtubule to attach to host), trypanosomiasis (infects fly which infect humans and can cause sleeping sickness or Chaga's disease, reproduces by longitudinal binary fission, localizes in heart and CNS)
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diseases caused by intestinal nematodes
enterobiasis, ascariasis, hookworm infections
*severity of disease depends on the level of adaptation to the host*
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enterobiasis
nematode, pinworm, temperate regions of europe and north america, transmitted in gatherings of children, pinworms attach to cecum of large intestine and eggs leave the anus which are then transferred through the fecal-oral route
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Ascariasis
nematode, roundworm, picked up from eggs in soil, parasite lives in small intestine, larvae enter the liver, travel through hepatic vein into lungs where they are coughed up and swallowed, regaining access to the intestine
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microfilariae
live offspring of nematodes
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trichinosis
nematode, lives in duodenal of swine and bears, enter vascular system and penetrate tissues, if a carnivore eats swine diseases is transferred
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cestodes
tapeworms, largest intestinal parasite, lack vascular respiratory and digestive systems, body has a head (scolex) a regenerative neck and a long segmented body, severity of tapeworm infection depends on if patient is primary or intermediate host
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trematodes
flukes, can be hermaphrodites or schistosomes,
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miracidia
if eggs from nematode reach water they hatch and lay these ciliated larvae, reach snails and reproduce into tail-bearing larvae called cercariae, this is finish is schistosome but if hermaphrodite the cercariae enter a plant and animal and develop into metacercariae which then can infect humans
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types of flukes
lung fluke, liver fluke, and blood flukes
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mycology
study of fungi, unicellular (yeasts) and multicellular (molds)
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how is the plasma membrane of fungi different from bacteria?
fungal cells have sterol erogsterol and are surrounded by a cell wall made of the polysaccharides mannan glucan and chitin
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conida
asexual reproductive elements of fungi, involves mitotic division
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blastoconida
budding of yeast, new cell projects from an existing cell
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hyphae
seen in molds, tubelike extensions of the cytoplasm, intertwine to form mycelium which then cross to for septa (cross walls)
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dimorphism
some fungi can grow in either a yeast or mold form depending on the environment (temperature and nutrients)
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mycosis
any disease caused by a fungus, superficial mycosis does not involve tissue response
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piedra
colonization of the hair shaft characterized by nodules attached to the hair
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tinea nigra
fungal superficial skin lesions
ex) tinea corpis is ringworm
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pityriasis
dermatitis caused by itching of the skin, yeast, folliculitis
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tinea capitis
scalp and eyebrows fungal infection
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favus
hair loss due to permanent destruction of hair follicle
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different ringworm classifications
tineas pedis (athletes foot), tinea corporis (fingers/palm), tinea cruris (genitals)
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onychomycosis
nailbed and nail infection
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mucocutaneous candidiasis
caused by candida albicans, thrush or vulvovaginitis, yeast infection
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hyperkeratosis
scaly areas on hands and feet
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keratitis
colonization of corneal epithelium (eyes), caused by careless contact applications
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sporotrichosis
subcutaneous mycoses, occur after traumatic implantation of fungal organism
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paranasal conidoblomycoses
infection of paranasal sinuses that form granulated fibrotic tissue
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zygomatic rinitus
mucosa become grayis, invades tissue through the arteries causing blood clots
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types of deep mycoses
localized or systematic, often seen in immunocompromised patients
systematic: localized to deep tissues and organs
disseminated mycosis: moves from the initial site from blood or lymph
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pathogenesis of fungal infections
adherence: adhere to the mucosal surface of GI or female genital tract
invasion: introduced to tissues through mechanical breaks in the skin
tissue injury: host inflammatory and immune response
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phagocytosis
neutrophils kill any fungal hyphae that reach tissues
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