Final Review Flashcards
(234 cards)
1
Q
Is a virus a living organism
A
no
2
Q
what is the smallest unit of life
A
a cell
3
Q
what are cells comprised of( generally)
A
macromolecules
lipid, protein, nucleic acid, polysaccharides
4
Q
What forms proteins
A
amino acids
20 different types
5
Q
what is an essential amino acid
A
cannot be made by the body and must be taken in from environment- usually via food
6
Q
what are the 2 major nucleic acids
A
DNA: deoxyribonucleic acid
RNA: ribonucleic acid
7
Q
what is the function of RNA and DNA
A
nucleic acids carry genetic material within a cell
DNA: contains the genetic information for a living organism and responsible for the characteristics
RNA: deciphers the genetic material and produces proteins
8
Q
What is composition of plasma membrane
A
bilayer of lipid
has hydrophobic tail that points in
9
Q
how many carbons are present in glucose
A
6
10
Q
is the genetic material in a prokaryotic cell contained in a membrane
A
no: only eukaryotic have genetic material in a nucleus
11
Q
can prokaryotic cells be subdivided into bacteria and Archaea
A
yes they can
12
Q
What is archaea and can they survive harsh climate
A
prokaryotic organism and yes they can
13
Q
Which organisms fall under eukaryotic classification
A
plantae, animalia, fungi and protista
14
Q
which organism gets most of their energy by converting light energy into chemical energy
A
plantae
15
Q
Name 2 organisms considered protista
A
amoeba and algae
16
Q
what is a defining characteristic of protista
A
inability of colonies to form tissue layers
17
Q
what is the function of a ribosome
A
protein synthesis
18
Q
where are ribosome located
A
in cytoplasm of prokaryotic cells and in endoplasmic reticulum of eukaryotic
19
Q
which organisms have cell walls
A
plantae, fungi, algae, bacteria
20
Q
what is the primary function of mitochondria
A
to produce energy: in ATP form
21
Q
How are animale organisms classified
A
heterotropic
22
Q
microbiology is the study of
A
microbes and their processes
23
Q
what is a macromolecule
A
a complex molecule built from smaller units
24
Q
what is the function of protein in a cell
A
facilitate movement( in or out of cell), speed up or slow down reactions, provide structural support and enable general movement
25
what is the plasma membrane and what is it made of
a barrier that surrounds cell and separates inside from out
restricts movement of materials in/out of cell
composed of lipids: hydrophobic hydrocarbons
26
what are the 3 components of polysaccharides
carbon, oxygen, hydrogen
| example: C6, H12, O6- glucose
27
what is the primary difference between eukaryotic and prokaryotic cells
eukaryotic cells have a nucleus: contains genetic material
| prokaryotic cells do not have a nucleus classified as either bacteria or archaea
28
what are the different shapes( morphologies) of bacteria
coccus(round), bacillus(rod), vibrio(curved rod), spirilum( spiral)
29
which classification of microbes can survive under harsh conditions
archaea
30
Can viruses be considered eukaryotic or prokaryotic
no: they are not living organisms, they can't replicate unless they are in a host cell
31
what makes up the lipid bilayer of the plasma membrane
amphipathic phospholipids: hydrophobic tails( repel water) and hydrophilic heads( love water)
32
what are the primary cellular organelles described in module 1 and function
ribosome: protein synthesis
ER: site of protein synthesis
Golgi Appartus: protein modification and distribution
lysosome: waste disposal
mitochondria: energy production: ATP
Chloroplasts: photosynthesis: only in plants
33
Define cellular metabolism
a controlled set of biochemical reactions that occur to maintain life
34
What is the function of enzymes and how are they regulated
enzymes speed up reactions
| use a cofactor and without the cofactor will not be active
35
what is the difference between anabolism and catabolism
anabolism is the building of larger compound from smaller ones
catabolism is the breakdown of large compounds into smaller usable units
36
ATP has ability to , while ADP has ability to
donate, accept
37
How can chemotrophs be subdivided
organotrophs: remove electrons from organic compound
lithotrophs: remove electrons from inorganic compound
38
chemotrophs use which form of phosphorylation
oxidative: energy from chemicals
39
what are the 3 phases in catabolism of glucose
glycolysis: 2 ATP
fermentation/respiration: 2 ATP
electron transport: 34 ATP via oxidative phosphorylation at plasma membrane
40
what are reactants in glycolysis
reactions: left side of arrow: 2NAD+ and 6ATP
41
What are the two main strategies for replenishing cellular concentrations of NAD+, and when these strategies be utilized?
Fermentation and Respiration are the two strategies used by the cell to convert NADH (end product of glycolysis) back to NAD+. Fermentation occurs in the absence of oxygen (anaerobic conditions) while respiration occurs under aerobic (presence of oxygen) conditions. Notably, respiration is more efficient that fermentation.
42
How are TCA and ETC related
TCA: end of krebs cycle: used to fuel electron transport chain by producing NADH and FADH2
electrons are transferred to terminal ATP acceptors from NADH and FADH2; cause proton gradient and generation ATP synthase which then allows for 34 ATP to be produced
43
when sugar is not available: are entirely different metabolic processes used to metabolize alternative sugar sources( lactose or fructose?)
No: additional steps are needed to convert them to glucose before glycolysis can take place.
44
proteases break down
proteins
45
what are other sources of energy other than glucose
proteins, lipids, polysaccharides:
| lipids highest can be used in ETC and TCA cycles
46
photosynthesis takes place where
in the organelle
| chloroplast- double membraned and contain chlorophll
47
in phosphorylation: light reactions occur where
in the membrane of chloroplast
48
what are the products of light reactions used for in dark reactions
ATP and NADH produced
| used to convert CO2 and H20 into C atom and H= carbon fixation
49
?CO2+?ATP+?NADPH+?H20-> C6H12O6+?ATP+?NADP+
6CO2+18ATP+12NADPH+12H20->C6H12O6+18ATP+12NADP+
50
Name the following enzymatic reaction
| A-B → B-A
Isomerases
51
How is the specificity of an enzyme determined
by the active site
lock and key relationship
structure influenced by shape of amino acid: structure/ function
only specific proteins can bind to certain active sites
52
What assists enzymes during catalysis reactions and are metal ions
cofactors: metal ions assist catalysis reactions for enzymes
53
which process is active in order to convert proteins into amino acids
catabolism: breaking down larger macromolecule into smaller subunits
54
What is the energy transfer process relative to ATP and ADP
ATP has energy( phosphate) to donate
ADP has ability to accept (phosphate)
ATP-> ADP + Pi
ADP+Pi-> ATP
55
where do chemotrophs gain energy
chemical compounds( preformed) in their environment
56
which organism gains energy by removing electrons from sulfur
lithotroph
57
what is a reactive intermediate in phosphorylation
chemical losing the phosphate group
58
which phosphorylation process would you find a reactive intermediate
substrate-phosphorylation
59
which component of glucose catabolism yields the most energy
ETC: 34 ATP
60
Which are the reactants in the following
Glucose + 2NAD+→
2 NADH + 2 Pyruvate + 2 ATP
reactants are on the left side of the arrow
| glucose and 2NAD+
61
what are 2 roles in glucose-6-phosphate
signal that glycolysis is about to begin
| prevent glucose from leaving the cell
62
in the absence of O2- fermentation produces 2 ATP: T/F
F
| fermentation only reduces NADH to NAD+
63
What are the products of the TCA cycle
NADH and FADH2
64
Do the products of the TCA cycle fuel the ETC
yes: high volume of products from TCA is used by ETC to fuel production of ATP
65
Of the following: which can be used as alternative energy in the absence of glucose
nucleic acids, lipids, carbohydrates, lactose
lipid, lactose, carbohydrates
66
for the breakdown of lipids and proteins: which enzymes are used
lipase, protease, ligase, transferase
lipase and protease
67
What is the beta-oxidation pathway used for
catabolism of fatty acids
| not anabolism
68
what is the relationship between chloroplasts and chlorophyll
both chloroplasts and chlorophyll are involved with photosynthesis
chloroplasts are a double membrane organelle that contain chlorophyll
69
are chloroplasts specific to plants and algae
yes
70
photophosphorylation produces what
NADPH and ATP
71
Define the measurements micrometer and nanometer.
A micrometer (µm) is defined as being one-millionth of a meter and is commonly designated at 10-6 meters. A nanometer (nm) equals 10-9 m or one-billionth of a meter.
72
What are the two critical factors that influence your ability to see an object?
Resolution and contrast. Resolution refers to the distance between two objects at which the objects still can be seen as separate.
The contrast is the difference in light absorbance between two objects. Poor contrast gives a high background and makes the visualization of multiple objects difficult.
73
If you wish to increase the amount of light going into a microscope, what part would you adjust?
The iris diaphragm controls the amount of light that passes through the sample and into the objective lens
74
As light passes through a microscope, what is the last piece that light passes before reaching your eyes?
ocular lens, or eyepiece,
75
How is the total magnification of an object calculated?
Total magnification is calculated by multiplying the power of the objective and the power of the eyepiece. For instance, a 40x objective with a 10x eyepiece would make an object appear (40 x 10) 400 times larger (400x).
76
What is one limitation of fixing your sample?
Fixation requires you to irreversibly kill your sample. Thus, determining the motility (cell movement) of a sample is impossible. Fixation also runs the risk of distorting the specimen shape and arrangement.
77
Phase-contrast microscopy provided what benefits to imaging?
Phase contrast microscope can provide detailed images of live cells without staining. By using specialized condensers and objectives, a phase contrast microscope amplifies the slight differences between cells and the surrounding medium (background) to make the cells highly distinguishable.
78
What is the distinguishing feature of dark field microscopy
dark field microscopy reflects light off of the specimen at an angle. The resulting image is an exceptionally dark background and a vibrant specimen.
79
Unlike brightfield microscope, fluorescence microscopes illuminate samples through what spectrum?
ultraviolet (UV) spectrum.
80
What is the primary difference between TEM and SEM?
During transmission electron microscopy the electron passes through the sample whereas during scanning electron microscopy the electron is reflected off the sample creating a three dimensional ‘shell’ model of the specimen.
81
Gram staining is based on what basic principle?
Gram staining, developed by Hans Christian Gram in 1884, began with the basic observation that different types of bacteria react differently to various dyes. Some bacteria readily take up a specific dye while others do not.
82
What is a key determinant in a bacteria being Gram-positive?
Gram-positive bacteria have a thick peptidoglycan layer. The Gram stain exploits this characteristic by using the dye combinations of Crystal violet and Iodine. Crystal violet is retained by the thick peptidoglycan cell wall and forms a stable complex with iodine (upon its addition) effectively trapping the dyes in the cell. The resulting mixture is a purple coloration of the cell.
83
What is the purpose of heat fixing a sample?
Heat fixing ensures the samples tightly adhere to the glass slide prior to staining (and washing) procedures.
84
What is the primary purpose of a wet mount?
Wet mounts are most often performed to visualize live cells as well as the motility and behavior of an organism.
85
The acid-fast stain is most often used to identify what specific microorganism?
Acid-fast stains are used to identify bacterial stains showing a high degree of resistance to decolorization. Mycobacterium tuberculosis is the most common use for an acid-fast stain.
86
Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the magnification of a sample.
objective
87
What is the total magnification (relative to your eye) of a sample imaged with a 60x objective and a 10x eyepiece
60x10=600x
88
True or False: Staining is often required to image a cell that is adherent and flat (thin).
T
89
```
Which of the following could be seen clearly by the unaided eye? Select all that apply.
Virus with a diameter of 0.2 μm
Protozoa with diameter of 150 μm
Bacteria with diameter of 24 μm
Skin cell with diameter of 1500 μm
```
protozoa with diameter of 150 um
| skin cell with diameter of 1500 um
90
This type of microscope utilizes ultraviolet (UV) light to illuminate stained objects.
fluroescence
91
This type of microscope can provide detailed images of live cells without staining.
phase-contrast
92
This type of microscope enhances contrast between specimen and background but does not permit the visualization of intracellular structures.
dark field
93
This type of microscope uses neither halogen nor UV light sources but rather lasers to illuminate stained cells in high resolution.
confocal
94
Gram-Positive cells appear [answer1] in color due to a [answer2] peptidoglycan layer in the cell wall.
purple
| thick
95
Gram-Negative cells appear [answer1] in color due to a [answer2] peptidoglycan layer in the cell wall.
pink
| thin
96
True or False: Following the decolorization step of the Gram stain, Gram-Negative bacteria will appear colorless.
T
97
True or False: If you wish to study the motility of an organism you cannot heat fix, but you can chemically fix the specimen.
F
98
You want to observe the size and shape of a cell. What is the easiest staining technique that you could perform? Name at least one dye you would use during this process.
simple stain
| crystal violet, safranin, methlye blue, fuschin( any of the dyes would work)
99
You suspect a patient may have TB. Once a sample has been obtained, it is sent off to the lab for an acid-fast stain. If the patient were infected with TB, describe what you would expect to see on the stained slide.
You would expect to see red cells (TB+) on a blue background (TB negative).
100
True or False: A Giemsa stain can be used to determine the presence of pathogenic bacteria.
T
101
What is another name for a liquid growth media, and what are the basic components?
Growth media in a liquid form is often referred to as nutrient broth. As the name implies its composition consists primarily of essential ‘ingredients’ such as a rich source of sugars, amino acids and vitamins. Together, a nutrient broth provides the microbe with a source of carbon/energy, which, in turn, encourages its expansion.
102
What is selective media?
Selective media allows for only the growth of certain microbes while restricting the growth of all others.
103
What is differential media?
Differential media is used to distinguish between two (or more) related microbes.
104
What are the requirements of a fastidious microbe?
A fastidious microbe is an organism with complex growth requirements such that if absent it will not grow. Enriched medias thus contain these specific and essential nutrients required for the growth of a particular subset of microorganisms.
105
What is agar?
In its simplest form agar is liquid growth media that has had a hardening agent added to it. Agar is created when a polysaccharide derived from seaweed (algae) extract is added to growth media. Agar is used to create a solid, smooth surface on which microbes can grow.
106
True or False: LB agar is classified as a non-selective, differential media.
F
107
What are the three forms of hemolysis found on blood agar plates?
Alpha (green), Beta (clear zones) and Gamma (white/tan).
108
What is the primary purpose of Columbia CNA agar
As it suppresses the growth of Gram-negative bacteria CNA agar is, therefore, used for isolation of Gram-positive microbes.
109
Name the type of plate derived from BAP that contains lysed red blood cells.
Lysed red blood cells (RBCs) are a primary component in the formulation of Chocolate agar.
110
Define the selective and differential abilities of a MacConkey agar plate.
MacConkey agar is selective in that only Gram-negative microbes will grow on the agar
MacConkey agar is also considered a differential media as it distinguishes between microbes capable of fermenting lactose (red colonies) and those that are non-fermenters (white/tan colonies)
111
What colors would you expect to see on an EMB plate containing E. coli?
metallic green sheen.
112
What is the name of the process of spreading a bacterial culture onto a petri dish?
Plating. Plating microbes can be done using a sterile loop, a sterile swab, or a sterilized wire loop.
113
What is the primary advantage of plating a bacterial culture as opposed to having it grow in solution?
The primary advantage of plating a bacterial sample onto agar is that cells are held in place. Unlike in a nutrient broth where bacterial cells can multiply but are free to move around in solution, bacteria plated onto agar are fixed in such a way as to support the formation and visualization of colonies.
114
What is the purpose of the quadrant streak approach?
The purpose of this method is to generate an individual colony so that a single (pure) bacterial sample can be picked from the plate.
115
In a three-phase dilution gradient, which phase most likely contains individual colonies: phase 1 (P1) or phase 3 (P3)?
Individual colonies are most likely going to appear within the phase 3 streaks
116
True or False: Growth media is best suited for distinguishing between two similar species of bacteria
F
117
A researcher is asked to determine which of two vials contains E coli and which contains salmonella. Knowing both are Gram-negative while only one of them is capable of fermenting lactose, which type of media would be best suited?
differential
118
True or False: LB agar is classified as a selective, non-differential media.
F
LB agar is the most basic type of agar and like LB media supports the growth of virtually all microbes without restriction.
119
The polysaccharide-based hardening agent added to LB media to produce LB agar is derived from what?
seaweed
120
Blood agar is which type of medium?
differential and enriched
121
match the pairs
Alpha hemolysis A. No hemolytic activity
Beta hemolysis B. Incomplete hemolytic activity
Gamma hemolysis C. Complete hemolytic activity
alpha: B
Beta: C
Gamma: A
122
Columbia CNA agar is used to isolate:
gram positive
123
True or False: Chocolate agar gets its brown color from cocoa to produce an enriched media.
F
124
An unknown microbe is streaked onto a MacConkey agar plate. After an overnight incubation at 37°C, growth is observed. Would a Gram stain be necessary? Why or why not?
No. A Gram stain would not be necessary, as only Gram-Negative microbes will grow on MacConkey agar.
125
In an attempt to detect the presence of the pathogenic strain of E. coli O157:H7, a researcher spread a culture onto a MacConkey agar with failed results. What type of agar should they (correctly) try next? Why?
The microbe should be plated on SMAC (Sorbitol-MacConkey agar) as it is specifically formulated to detect O157:H7. Pathogenic E. coli (O157:H7) cannot ferment sorbitol while non-pathogenic E. coli can ferment both soribitol and lactose. Therefore, colonies that ferment (acidic conditions; non-pathogenic) can be differentiated from non-fermenters (neutral to basic conditions; pathogenic).
126
What is the Gram status (positive or negative) of microbes growing on Eosin Methylene Blue (EMB) agar plates?
Gram-Negative. EMB plates specifically restrict the growth of Gram-Positive bacteria.
127
Which type of agar media is best suited to support the growth of Staphylococcus?
Mannitol Salt Agar
128
What is the process of spreading a bacterial culture onto a petri dish?
plating
129
In order to visual individual colonies of bacteria would you culture your sample in a liquid media or on a solid (agar) media? Why?
Solid (agar) media. The primary advantage is that cells are held into place. When grown in a nutrient broth, bacterial cells can multiply but are free to move around in solution. When grown on agar within a petri dish the fixed in such as way as to form colonies.
130
True or False: The visualization of colonies on a petri dish represents bacterial cells that have multiplied ~2-3 times.
F
| When an individual colony is visible on agar the bacterial cell has multiplied often a million times over
131
True or False. The purpose of a quadrant streak is to expand a bacterial population.
F
The purpose of the quadrant streak is to generate individual colonies such that a single (pure) bacterial sample can be isolated.
132
To be considered a pure culture, the sample (1) can be traced back to a single cell and (2)__________ ?
The culture must also be free from external contaminants. Simply put, a pure sample would never contain multiple bacterial species (ie) Strep and Staph.
133
When performing a quadrant streak, the sample is spread across the plate in such as way as to form what?
A dilution gradient is formed. The resulting gradient should always contain within it the growth of individual colonies.
134
In what phase of a dilution streak would you expect to find the highest concentration of bacteria, P2 or P4?
P2 (Phase 2) would contain a higher concentration of bacteria than Phase 4 (P4). The phases rank (from highest to lowest), P1 > P2 > P3 > P4.
135
True or False. When performing a dilution streak a new (or sterilized) loop is not required for each phase as long as the bacterial culture is pure.
F
A new or sterilized loop is absolutely required for each phase. Failure to do so would prevent the establishment of a dilution gradient, as the same bacterial concentration would be spread across both phase regions, regardless of whether or not the culture is pure.
136
The number of phases (3 vs. 4) and/or the number of times a loop passes through a previous phase (once vs. multiple times) is acceptable provided what happens?
Either deviation is acceptable in practice provided the resulting gradient contains within it the growth of individual colonies—if not, the experiment must be repeated.
137
True or False. To restrict the growth of a pathogenic microbe a researcher might decrease an incubator from 37°C to 25°C.
T
Pathogenic strains of bacteria tend to grow faster than non-pathogenic strains at 37°C, so researchers may set incubators at 25°C to restrict its growth.
138
When given an unknown bacterial sample the first step is to expand the current bacterial population. Which form of media best suites this need? Why?
MSA agar
LB media
MacConkey agar
Columbia CNA agar
LB media. All other options (A, C and D) are all forms of selective media, meaning they may potentially inhibit the growth of the unknown sample. The culture should be first expanded and then place onto selective/differential agar plates.
139
Define the concept of universal precautions.
Universal precautions means any and all samples, whether known or unknown, are to be treated as potentially hazardous (or pathogenic) materials.
140
What would a researcher be certain to note while analyzing a microbial sample?
A lab researcher would be certain to note
1. Size and shape
2. Any observable motility
3. Gram status (positive or negative)
4. The presence of any chemical reactions
5. Changes in color localized to the organism or the surrounding media
6. Capture (or draw) images of any of the characteristics described above
141
Which non-selective yet differential agar plate should be used if a Streptococcus sample is suspected?
A BAP (blood agar plate) would be the quickest way to identify and classify a potential streptococcus microbe based on its hemolytic properties.
142
What disease can result if a patient with streptococcal pharyngitis goes untreated?
Rheumatic fever occurs in approximately 3% of untreated cases of streptococcal pharyngitis, presenting approximately 2-3 weeks post-infection.
143
Streptococcus, E. coli, pseudomonas, and klebsiella are all capable of causing what disease?
septicemia, also known as blood poisoning.
144
What is a facultative anaerobe?
A facultative anaerobe is capable of growth under both aerobic (with oxygen) and anaerobic (in the absence of oxygen) condition.
145
How can Staphylococcus be differentially tested?
Staphylococcus species are capable of growth in the presence of bile salts.
146
A bacterial swab is taken from a patient with impetigo and streaked across an MSA plate. Following incubation at 37C, what will be the color of the agar?
The causative agent of impetigo is staph aureus, a Gram-positive bacterium capable of fermenting mannitol. Fermentation will lower the pH of the agar and change the dye color from red to yellow.
147
If a patient were suspected to have tuberculosis (TB), which differential stain would you select and why?
To stain for TB, one would utilize an acid-fast stain to best visual the foreign microbe. As a mycobacterium tuberculosis would stain poorly (indeterminate) using the Gram stain.
148
According to the module, which mycobacterium infection will be treated free of charge by the World Health Organization (WHO)?
Leprosy is completely curable using a multiple-drug therapy regimen consisting of various combinations of the drugs dapsone, rifampin and clofazimine—all of which is given free of charge.
149
What are the three main conditions caused by the botulism toxin?
Foodborne, infant and wound. Foodborne botulism is often the result of improperly canned, contaminated, low-acidic foods such as green beans, corn and beats. Infant botulism occurs when children, usually under the age of 6 months consume foods containing the bacteria. A potential source of infant botulism is honey (which is why pediatricians recommend avoiding feeding honey to infants) but can also be found in common places such as soil. Wound botulism occurs when C. botulinum bacteria colonize a deep wound, often a puncture such as those who inject street drugs such as heroine.
150
Why are infants (< 6 months) more susceptible to botulism?
Due to infants still maturing intestinal tract and lack of an adult microbiota, the bacteria are able to colonize and produce the associated toxin. In adults, only the direct ingestion of the pre-formed toxin causes disease—ingestion of C. botulinum or the associated spores do not cause illness as a mature intestinal microbiota sufficiently prevents bacterial germination and growth.
151
What is the mechanism of action of the toxin produced by clostridium tentani (tetanus)?
The toxin acts on inhibitory neurons causing systemic muscle stiffness and spasms. Muscle stiffness can be observed in the jaw (lock-jaw) or spread systemically (if left untreated) to muscles relating to respiratory function.
152
What Gram-negative bacterium might you come into contact with in a unsanitary hot tub?
Legionella is often associated with unclean water systems such as hot tubs, hot water tanks and AC units. Notably, legionella can only be transmitted through water droplets small enough to be inhaled.
153
What are the three forms of plague, and what regions do they affect?
Bubonic (lymph), pneumonic (lungs) and septicemic (blood). Bubonic plague is best characterized by painfully swollen lymph nodes. Pneumonic plague affects the respiratory system (lungs). The most rare of all three plagues, septicemic plague targets the blood system
154
According to the module, which STD might be best identified via dark-field microscopy?
Syphilis. The causative agent, treponema pallidum, is a thin spirochete, making Gram staining (and visualization) difficult
155
The concept of treating all samples, whether known or unknown, as potentially hazardous (or pathogenic) materials is known as __________.
universal precautions
156
List at least 3 observations a researcher would be sure to note while assessing an unknown microbial sample.
A lab researcher would be certain to note:
Size and shape
Any observable motility
Gram status (positive or negative)
The presence of any chemical reactions
Changes in color localized to the organism or the surrounding media
Capture (or draw) images of any of the characteristics described above`
157
While observing an unknown sample of limited amounts, a researcher must determine the following observations: (1) the presence of any motility and (2) its Gram status using the same sample—the liquid sample cannot be divided. Which would you determine first and why?
motility: requires a wet mount
to do a gram stain would require heat fixing the sample which would kill the organism. This would lose any ability to see the motility of the organism.
158
A facultative anaerobe is a microorganism capable of growth under what conditions?
A facultative anaerobe is capable of growth under aerobic (with oxygen) and anaerobic (without oxygen) conditions.
159
As Streptococcus is catalase negative would it thrive or die in the presence of peroxides? Why?
Streptococcus would not survive in the presence of peroxides—it is unable to breakdown peroxides (catalase negative). Left unchecked, peroxides would damage the cellular integrity of Strep causing lysis/cell death.
160
Streptococcus is most often streaked onto:
BAP
161
True or False. The Lancefield groups are used to subdivide antigenic groups of alpha-hemolytic Streptococcus.
F
162
Greater than 90% of all human streptococcal infections belong to:
group A
163
Rheumatic fever displays ______ hemolytic activity and occurs when _______ is left untreated.
Beta
| strep. pharyngitis
164
True or False. Under most circumstances, staphylococcus can be found in ~80% of human population where it remains non-symptomatic.
F
| only 30%
165
Define commensal bacteria.
The bacterium neither harms nor benefits from the host from which it obtains nutrients.
166
How can staphylococcus be differentially tested?
Staphylococcus species are capable of growth in the presence of bile salts.
167
Name the disease based on the symptoms
A. Childhood skin disease near nose or mouth
B. Infection of thin, transparent scleral tissue
C. Infection occurs at time of birth
D. Pus-filled lesions on skin or hair
E. Ruptured pustules; treated with penicillin
```
A. Impetigo
B. Conjunctivitis
C.ophthalmia neonatorum
D. Folliculitis
E. Scalded skin syndrome
```
168
True or False. Staphylococcus is the only causative agent of conjunctivitis.
F
169
True or False. Tuberculosis is best identified by a Gram stain.
F
| acid fast stain is best
170
True or False. When located outside of the lung, TB is usually non-infectious.
T
171
Identify the disease based on the following (select all that apply):
It is a small, acid-fast rod usually remaining asymptomatic for up to 20 years. It affects the skin, nerves, upper respiratory tract, and eyes of infected individuals.
Scalded skin syndrome, TB, Hanson's disease, leprosy, bacterial conjunctivitis
hanson's disease
| leprosy
172
True or False. Only directly ingesting the pre-formed clostridium toxin (neither the bacteria nor its spores) will cause disease in adults.
T
173
While visiting his grandparents, a 10-year-old child has green beans for dinner that were harvested from his grandparents’ garden and canned the previous year. Severe illness sets in and the child is taken to the hospital. Botulism is suspected, but what form? Explain your answer.
Foodborne botulism. The child is too old (> 6 months) to be considered for infant botulism and wounds were not present. The green beans were likely improperly canned and under the low-acidic, anaerobic conditions, bacterial growth was encouraged.
174
True or False. There are currently no cures for tetanus.
T
175
Identify the medical condition characterized by robust carbohydrate fermentation under anaerobic conditions, swelling of the infected areas and fever.
Gas gangrene. The key identifier here is the robust carbohydrate fermentation, which manifests as intense gas production and swelling—both trademark conditions of gas gangrene.
176
Why does the alpha toxin (perfringolysin) produced during an infection of gas gangrene cause cell death?
The toxin perforates the membrane. It forms pores in the plasma membrane of host cells resulting in uncontrolled ion fluxes and eventually cell lysis and death
177
You develop a fever, chills, and pneumonia after recently returning from a getaway weekend where you sat in a hot tub. What bacterial disease would a doctor suspect is causing your symptoms? Would the doctor suspect you contracted it from another person?
Legionnaires. No—legionella cannot be spread simply by direct contact between people. Legionella can only be transmitted through droplets small enough to be breathed in.
178
True or False. Bubonic plague is often characterized by painfully swollen lymph nodes.
T
179
Which form of the plague is highly virulent? What does it target?
Pneumonic plague is highly virulent and targets the respiratory (lungs) system.
180
Syphilis is caused by:
gram negative spirochete
181
True or False. Chlamydia trachomatis can be grown on an agar plate alone.
F
182
Can viruses be classified as either prokaryotic or eukaryotic microorganisms?
No. Viruses are neither prokaryotic nor eukaryotic.
183
What is an obligate intracellular parasite?
As an obligate intracellular parasite, viruses cannot (obligate) replicate unless inside (intracellular) a living host cell. As a parasite, a virus depends on its living host to provide the framework (proteins, etc) to replicate—to make additional copies of itself.
184
What is a viral capsid?
The capsid is a membrane-like protective structure that contains the genetic material, similar to the nucleus of a eukaryotic cell.
185
What is the viral envelope, and what does the presence (or absence) of it tell you about the type of virus?
The envelope surrounds the viral capsid, is derived from the host cell membrane and serves as an additional barrier to the external environment. The overwhelming majority of animal viruses are enveloped whereas the majority of plant or bacteria-infecting viruses are not.
186
What type of microscope would be used to study the shape of a viral capsid?
Due to its size (~30-150 nm) most viral capsids must be visualized via electron microscopy.
187
How does the viral envelope both aid in cell entry as well as hide it from being detected by the immune system?
The viral envelope contains the necessary proteins required for interaction with host cells. As the envelope is derived from the host cell membrane, this camouflages the virus and lowers the likelihood of immune detection by making it appear similar to the normal biological host cell.
188
What must happen before viral replication of its genome can occur?
For all viruses, the genome is replicated following attachment and entry, never before.
189
Describe the basic steps of the viral life cycle.
1. Attachment: Viral receptors bind to host proteins on the surface of the cell.
2. Entry: The virus fuses with the host membrane and enters the cell
3. Uncoating: (where applicable) the viral capsid disassembles
4. Replication: The viral genome provides the ‘blueprint’ to make copies of itself
5. Exit: New viruses are produced and leave the cell
6. New infection: Newly produced viruses leave the host cell and go on to infect new cells. The process outlined above now restarts.
190
What is a bacteriophage?
A bacteriophage is simply a virus (phage) that infects bacteria.
191
What structural aspects make bacteriophages distinct from viruses that infect either animals or plants?
Bacteriophages possess an icosahedral capsid head group and a helical tail. Attached to the tail are fibrous extensions or ‘legs’ that aid in binding host cells. Notably, this particular structural arrangement has not been observed among viruses that infect either animals or plants.
192
Which viral replicative process results in the destruction of the host cell?
The lytic replication cycle occurs when a bacteriophage replicates within a host until it ruptures, effectively destroying the host bacterial cell. The phrase lytic stems from ‘lysis’, meaning to rupture or disintegrate (breakdown) a cell.
193
Describe the appearance of a bacterial culture infected with virus at the time of infection versus later once viral replication is occurring at a high rate.
During the initial inoculation of virus and bacteria, the media has a high degree of turbidity (cloudiness). However, as the lytic cycle progresses and more and more bacterial cells are destroyed, the culture media turns from turbid to clear, as turbidity is a function of the number of intact bacterial cells present in the media. Thus, as bacterial cell numbers decrease due to lysis, the media becomes clearer.
194
To what family of viruses does rubella come from and how is it transmitted?
Rubella virus belongs to a family of viruses called Togaviridae. Rubella is transmitted via air-borne particles such as when a person coughs.
195
What is the common name for rubeola, and is it a DNA or RNA virus?
Rubeola is commonly referred to as the measles and belongs to the family of viruses called Paramyxovirus. Rubeola viruses are RNA viruses with a genome ~ 15,000 nucleotides long.
196
What disease state emerges as a viral reactivation of a prior infection with the varicella virus?
Shingles, also known as Herpes zoster, is due to the reactivation of the varicella-zoster virus (VZV). Because VZV lies dormant in inactive nerve cells, its reactivation typically results in painful blisters. However, unlike the initial chickenpox rash, the blisters are localized and limited to small areas.
197
What linear, double-stranded, enveloped DNA virus is the first virus (as of October 26, 1977) to be declared eradicated?
Although once a major cause of death in the world, a smallpox vaccine was developed in 1796 by Edward Jenner. Global vaccination efforts have prevented smallpox from appearing in humans since October 26, 1977, making smallpox the first infectious disease ever to be eradicated.
198
What are the two key glycoproteins found in the influenza virus?
The viral envelope contains two key glycoproteins, hemagglutinins (HA) and neuraminidase (N). Hemagglutinins are heavily involved in the entry of the viral particle into a host cell, while neuraminidase proteins are involved in the budding and release of new viral particles from the host cell.
199
Describe the composition of HIV.
HIV contains two copies of single-stranded, linear RNA that is enclosed by a capsid. The conical capsid surrounds the two RNA strands and is comprised of ~2,000 copies of the viral protein p24. A viral envelope derived from the cell host membrane then surrounds the viral capsid. Within this envelope are two key glycoproteins, gp120 and gp41, which are essential for viral binding and entry into the host cell.
200
True or False. Because the genome is contained within an enclosed space (much like the nucleus of a cell), viruses are classified as eukaryotic.
F
201
Describe the two basic components of a virus.
A virus has (1) genomic material comprised of either DNA or RNA and (2) a capsid, a membrane-like protective structure that contains the genetic material, similar to the nucleus of a eukaryotic cell.
202
The envelope surrounds the _________ of some viruses.
capsid
203
True or False. You would expect to see a viral envelope on a virus infecting a plant cell.
F
204
Rank the following viruses based on their size from largest to smallest:
Orthomyxovirus
Poliovirus
Variolavirus
variolavirus
orthomyxovirus
poliovirus
205
True or False: Viral replication occurs after it attaches and enters the host cell.
T
206
```
Place the following viral life cycle steps in order beginning with viral attachment and provide a description of each step.
Uncoating:
Release:
Replication:
Attachment:
Entry:
New infection:
```
3- Uncoating: the viral capsid disassembles
5-Release: New virus particles are produced and leave the cell
4-Replication: the viral genome is the ‘blueprint’ to make copies of itself
1-Attachment: viral receptors bind to host proteins on the surface of the cell
2-Entry: the virus fuses with the host membrane and enters the cell
6-New infection: newly produced viruses that left the host cell now go on to infect new cells.
207
A virus that infects bacteria is called a [answer1] and contains a [answer2] -sided polygon capsid.
bacteriophage
| 20
208
True or False. Structurally, bacteriophages are similar to viruses that infect animals.
F
209
Describe the main differences between lytic and temperate phages.
tic bacteriophages replicate within the host bacteria until it ruptures, whereas temporate (or lysogenic) phages primarily exist in a non-replicative state that does not kill the host cell.
Lytic phages replicate all viral proteins needed for the assembly of new virus particles whereas lysogenic phage genomes are integrated into the host genome but production of viral proteins is suppressed.
210
```
Which of the following can be spread via airborne particles:
Measles
Mumps
Rubella
A and B
All of the above
```
all of the above
211
True or False. A patient infected with rubella is considered infectious one week before and after the appearance of the trademark rash.
T
212
```
A patient diagnosed with German measles may additionally experience what disease? Select all that apply.
Impetigo
Conjunctivitis
Rheumatic fever
Influenza like symptoms
```
influenza like symptoms
| conjunctivitis
213
```
Which of the following diseases does a linear, double-stranded DNA virus cause?
Measles
Mumps
Rubella
B and C
None of the above
```
None of the above
| all diseases listed are RNA
214
What disease displays as a secondary characteristic swelling of the testes/ovaries and pancreas?
Mumps. A patient infected with mumps (aka epidemic paratitis) has primary swelling in the paratoid (salivary glands) located in the neck but also may have secondary swelling in the testes/ovaries and pancreas.
215
Describe two ways chickenpox can be spread.
Chickenpox is highly contagious and can be transmitted (1) through both air-borne droplets (sneezing/coughs) or via (2) direct contact with the blisters of an infected individual.
216
True or False. Someone who had chickenpox as a child is likely to develop shingles while in college, where the median age of college students is 18-22 years old.
F
217
True or False. Unlike chickenpox, the blisters that appear with shingles are localized and limited to small areas.
T
218
A person who has neither previously had chickenpox nor been administered the VZV vaccine is exposed to someone with an active VZV (shingles) outbreak and becomes infected. Explain why (or why not) the person will only develop shingles.
The infected individual will not develop shingles, but will develop chickenpox. Unvaccinated and unexposed individuals must first develop chickenpox, as shingles is the reactivation of the dormant VZV virus from the chickenpox infection.
219
While traveling abroad, should you be worried about coming into contact with either the Variola major or Variola minor viruses?
No. Both viruses are variants of smallpox and were eradicated in 1977. You would not need to worry about coming into contact with the virus.
220
What small (~30nm) single-stranded, non-enveloped RNA virus causes temporary or permanent paralysis by infiltrating (infecting) motor neurons within the spinal cord, brain stem, or motor cortex?
Polio, also known as poliomyelitis.
221
Describe the main underlining differences between the Salk and Sabin polio vaccine.
The Salk vaccine contained an inactivated form of the virus and was injected while the Sabin vaccine contained a live attenuated (weakened) form of the virus and was administered orally.
222
Which subtype of Influenza is the most virulent?
A
223
A drug company is trying to develop a new drug that will inhibit the release of newly produced viral particles. Would the drug company target hemagglutinin proteins or neuraminidase proteins? Why?
Neuraminidase (N) proteins are directly involved in the budding and release of new viral particles and would thus be the correct target. Hemagglutinin (HA) proteins would not be advisable targets as they are directly involved in viral attachment and entry into the host cell.
224
Explain why the flu shot given each year may not be 100% effective at preventing the flu?
It is possible to receive a flu vaccine and yet (unfortunately) still get the flu in the same season if you are exposed to a viral strain that was not included in the vaccine. There are a large number of variants and the flu vaccine is unable to vaccinate against all subtypes. Medical researchers predict and then distribute flu vaccines based current trends and the available data relative to the most common circulating strains. Unfortunately, this model is not always 100% accurate.
225
True or False. The viral capsid of HIV is cone shaped and contains ~2,000 copies of the viral protein p24.
T
226
The HIV surface glycoprotein gp41 binds what host cellular receptor?
CXCR4
227
An individual infected with HIV is placed on anti-retroviral medication. Describe how the medication will affect the virus.
As the name suggests, anti-retrovirals are intended to inhibit (anti) the process of reverse-transcription (retro). Once the virus enters the cell and uncoating is complete, the viral enzyme reverse transcriptase (RT) acts on the two RNA copies, creating a complementary DNA strand. Anti-retrovirals attempt to block this step. In the absence of anti-retroviral medications, the now double-stranded DNA is transported to the nucleus where it can integrate into the host genome and begin replicating. By inhibiting the process of RT, anti-retroviral medications effectively block the production of new viruses by preventing its integration and replication.
228
describe the parts of a bacteriophage: draw it out
```
icosahedral capsid
collar: neck region
tail: circular and extends down
base plate: bottom plate at end of tail
tail fibers: extensions off of base plate
```
229
Name the following enzymatic reaction
| A-B+H20->A-OH+B-H
Hydrolyase
230
Name the following enzymatic reaction
| A+B->A-B
Ligase
231
Name the following enzymatic reaction
| A-B->A+B
Lyase
232
Name the following enzymatic reaction
| A-+B->A+B-
Oxidoreductase
233
Ab+C->A+Cb
transferase
234
What is the reaction for glycolysis
glucose+2NAD+(2ADP+2pi)->2 pyruvate +2NADPH+2ATP+2H+
