Exam 3 Flashcards
(281 cards)
1
Q
Viruses differ from bacteria in that viruses:
A. Do not have any nucleic acid
B. Are obligate intracellular parasites
C. Are filterable
D. Are not composed of cells
A
D. Are not composed of cells
2
Q
How is a persistent viral infection different from a latent viral infection?
A. It remains in equilibrium with the host
B. It can be reactivated by immunosuppressive therapy
C. The infectious virus appears suddenly
D. The infectious virus gradually builds up over a long period of time
A
D. The infectious virus gradually builds up over a long period of time
3
Q
What is the function of viral spikes?
A
Attachment; which contributes to specificity (tropism)
4
Q
The envelope of viruses often serves as protection because it contains spikes that are antigenic. What does the envelope mean in terms of treating viruses?
A
Envelopes are often more susceptible to disinfectants, which may mean that enveloped viruses are easier to treat
5
Q
What are the steps of viral replication?
A
Attachment, penetration, uncoating, biosynthesis, maturation and release
6
Q
What are two ways for viruses to attach and penetrate the host cell?
A
Pinocytosis (after attaching with spikes)
Fusion (requires viral envelope)
7
Q
What enzyme helps a retrovirus integrate into the host cell genome?
A
Integrase
8
Q
Why is HIV an exception to viral maturation and release?
A
HIV does not mature until after budding has occurred. Maturation involves cleavage of protein units with proteases
9
Q
What type of virus is described as remaining in asymptomatic host cell for long periods of time, such as cold sores or shingles?
A
Latent
10
Q
What type of virus is described as a disease process occurring over a long period of time and is generally fatal such as measles?
A
Persistent (chronic)
11
Q
How is HIV transmitted and how is its transmission unique?
A
HIV is transmitted when infected blood, semen, or vaginal secretions come in contact with broken skin or mucous membranes
Unique because sexual transmission is 100,000x more virulent than other transmission methods due to high number of dendritic cells in mucous membranes and dendritic cells have CCR5 receptors
12
Q
What receptors are important for HIV attachment?
A
HIV has a Gp120 spike that attaches to CD4 cells and requires co-receptors CCR5 and CXCR-4
13
Q
What phase of HIV begins 2-8 weeks after initial infection and patients experience brief flu-like illness followed by rapid multiplication and dissemination of virus throughout the body and stimulation of the immune response?
A
Acute phase
14
Q
What phase of HIV may last from 6 months to 10 years, at which time levels of detectable HIV in blood decrease, although viral replication continues (particularly in lymphoid tissue)
A
Asymptomatic (latent)
15
Q
What phase of HIV can last for months to years, at which time viral replication continues and numbers of CD4+ cells in blood significantly decrease (resulting in patients developing a variety of illnesses often caused by opportunistic pathogens and AIDS related cancers)
A
Chronic symptomatic
16
Q
What stage of HIV is represented when the immune system is no longer able to defend against the virus
A
AIDS (fourth and final stage)
17
Q
How is HIV diagnosed? (Most common way, and most sensitive way)
A
Most common: detection of specific anti-HIV antibodies in the blood by ELISA assay followed by confirmation with Western blot technique
Most sensitive: using polymerase chain reaction
18
Q
The treatment of HIV/AIDS is directed at reducing the viral load, disease symptoms, and treating disease and malignancies. The most successful treatment involves a combination of what types of drugs?
A
Nucleoside RT inhibitors (AZT) Nonnucleoside RT inhibitors (delavirdine) Protease inhibitors (indinavir) Fusion inhibitors (enfuvirtide)
19
Q
Why is HIV/AIDS treated with a combination of drugs?
A
Reverse transcriptase is very prone to errors due to poor proofreading mechanisms, this makes it very easy for HIV to develop resistance to treatment very quickly due to viral evolution
20
Q
What is the biggest issue with trying to develop an HIV vaccine?
A
Envelope proteins of virus continually change their antigenic properties
21
Q
What is the largest group of known viruses?
A
Double-stranded DNA viruses
22
Q
Where is the herpesvirus virion envelope derived from?
A
The host’s golgi apparatus membrane
23
Q
Where is the herpesvirus latent infection taking place if the viral protein VP16 and host cell factor (HCF) enter the nucleus with the viral genome?
A
epithelial cells
24
Q
Where is the herpesvirus latent infection taking place if VP16 and HCF do not enter the nucleus, resulting in decreased early gene expression and microRNA production?
A
neurons
25
What are the different types of Herpes Simplex presentation?
Cold sores aka Fever blisters
Herpes gladiatorum - vesicles on skin
Herpes whitlow - vesicles on fingers
Herpes encephalitis
26
What are all possible names for HHV-1?
HSV-1, herpes simplex 1, oral herpes
27
What is the cell target for HHV-1?
epithelial cells and nerve cells
28
Where does HHV-1 remain latent?
Typically in the trigeminal nerve, but it can also remain latent in the vagus nerve
29
What are some unique features of HHV-1 in terms of signs/symptoms, cell features, and treatment options?
Signs/symptoms: cold sores, gingivostomatitis, herpetic keratitis (cornea)
Cell features: multinucleated (used in diagnosis)
Treatment: Acyclovir, education for prevention
30
What are all possible names for HHV-2?
HSV-2, herpes simplex 2, genital herpes
31
What is the cell target for HHV-2?
epithelial cells and nerve cells
32
Where does HHV-2 remain latent?
Sacral nerves
33
What are some unique features of HHV-2 in terms of transmission, signs/symptoms, cell features, and treatment options?
Transmission: STD or congenital (associated with high mortality rate)
Signs/symptoms: fever, burning sensation, genital soreness, blisters
Cell features: multinucleated (used in diagnosis)
Treatment: Acyclovir, education for prevention
34
What are all possible names of HHV-3?
Human herpesvirus 3, Chicken Pox (Varicella), Shingles
35
What is the cell target of HHV-3?
epithelial cells and nerve cells
36
Where does HHV-3 remain latent?
dorsal root ganglia of cranial/sensory nerves
37
What are some unique features of HHV-3 in terms of reservoir, signs/symptoms, and treatment options?
Reservoir: humans
Signs/symptoms: varies from Varicella to Shingles, may have viremia - bloodstream infection
Treatment: vaccination for Varicella, Acyclovir for Shingles
38
What are all possible names for HHV-4?
Ebstein Barr virus (EBV), Infectious mononucleosis
39
What is the cell target of HHV-4?
B cells and epithelial cells
40
What are some unique features of HHV4 in terms of cell features, complications, and signs/symptoms?
Cell features: mononucleated (proliferation of monocytes)
Complications: Oncogenic -> Burkitt's Lymphoma or nasopharyngeal carcinoma
Signs/symptoms: Often asymptomatic in children, swollen lymph nodes, spleen enlargement
41
What are all possible names of HHV-5?
Human cytomegalovirus (HCMV), Inclusion disease
42
What is the cell target of HHV-5?
CMV can infect any cell!
43
Where does HHV-5 remain latent?
White blood cells
44
What are some unique features of HHV-5 in terms of cytopathic effects, treatment options, and risk of transmission?
Cytopathic effects: causes formation of inclusion bodies in cytoplasm or nucleus of cells
Treatment options: Antiviral therapy
Transmission risks with organ transplants or blood transfusions, can also cross placenta
45
What are all possible names of HHV-8?
Human herpesvirus-8, Kaposi's Sarcoma
46
What is the cell target of HHV-8?
Lymphocytes and other cells
47
What are some unique features of HHV-8 in terms of signs/symptoms and complications?
Complications: causes Kaposi's Sarcoma (oncogenic) which is indicated by skin lesion, KS is common in AIDS patients
48
Which herpes viruses may lead to hepatitis?
HHV-4 (EBV) and HHV-5 (CMV)
49
Almost all forms of Hepatitis have an RNA genome, what type did we learn has a DNA genome?
Hepatitis B
50
Which type of Hepatitis is a current epidemic?
Hepatitis C
51
Which types of Hepatitis are thought to be carcinogenic?
Hepatitis B and Hepatitis C
52
Which types of Hepatitis exist as co-infections?
Hep D (with Hep B) and Hep E (with Hep A)
53
Which types of Hepatitis cause chronic liver disease?
B, C, and D
54
Which types of Hepatitis have vaccines and what type of vaccines are they?
Hep A (also covers Hep E) - inactivated HAV
Hep B (also covers Hep D) - recombinant HBV
55
Which type of hepatitis is characterized by DANE particles as its infectious form?
Hep B
56
What do Hep B, C, and D have in common in terms of transmission?
Parenteral transmission possible!
57
What type of genome is seen with the influenza virus?
RNA with segmented genome
58
What is the reservoir for influenza?
numerous animal reservoirs, i.e., swine, birds
59
What is the difference between hemagglutinin (HA) and neuraminidase (NA) spikes found on influenza virus?
HA spikes = attachment
NA spikes = release
Spikes determine influenza subtype
60
Why is there a new version of the flu vaccine each year?
Antigenic shift and antigenic drift
61
Describe antigenic drift
occurs due to accumulation of mutations in a strain within a geographic area (more local)
may involve only 1 amino acid
allows virus to avoid mucosal IgA antibodies
62
Describe antigenic shift
Changes in HA and NA spikes due to reassortment of genomes when two different strains of flu virus (from humans and animals) infect the same cell and are incorporated into a single new capsid
For example: H1N1 - swine flu, H5N1 - bird flu
63
Koplik's spots are diagnostic for:
A. Rubella
B. Measles
C. Herpes simplex
D. Chickenpox
B. Measles
64
Shingles is caused by the reactivation of the latent organism:
A. Human parvovirus B19
B. Human herpesvirus 3
C. Rubella virus
D. Human herpesvirus 6
B. Human herpesvirus 3
65
Which virus infects pregnant women and causes birth defects?
A. Ebstein-Barr virus
B. Cytomegalovirus
C. Hantavirus
D. Marburg virus
B. Cytomegalovirus
66
Ebola virus is transmitted from human to human by:
A. Contact with blood
B. Inhalation
C. Arthropod vector
D. Ingestion
A. Contact with blood
67
Describe Measles (Rubeola) virus in terms of genome, transmission, signs/symptoms, and treatment/prevention
Enveloped RNA virus transmitted through respiratory tract
Signs/symptoms: initial cough followed by macular rash and Koplik's spots in the mouth
Treatment/prevention: Symptomatic/supportive therapy, prevention by live-attenuated MMR vaccine
68
Describe the Mumps virus in terms of genome, clinical manifestations (signs/symptoms), and treatment/prevention
Enveloped RNA virus with 16-18 day incubation period
Signs/symptoms: fever and swelling/tenderness of salivary glands (possible complication = meningitis or orchitis)
Treatment/prevention: symptomatic/supportive therapy; live-attenuated MMR vaccine
69
Describe Rubella (German Measles) virus in terms of genome, transmission, symptoms, complications, and prevention
Enveloped RNA virus transmitted through respiratory droplets
Symptoms: mild, brief rash
Complications: Congenital rubella syndrome leading to fetal death, premature delivery, or congenital defects
Prevention: live-attenuated MMR vaccine
70
Describe Human Papillomavirus in terms of genome, characteristics, transmission, and treatment
DNA virus that causes verrucae (horny projections on skin)
Infects epithelium and mucous membranes causing benign epithelial tumors or certain cancers (cervical, pharyngeal)
Transmitted by direct contact and autoinoculation
Treatment: physical destruction (activates immune response), topical medications, or injection of IFN-alpha
71
Which type of HPV do we have a vaccine for?
HPV 16, which should protect against 80-100% of cervical cancers and other cancers (pharyngeal)
18 is also carcinogenic
72
Describe Polio virus in terms of genome, characteristics, and clinical signs/symptoms
Plus(+) strand RNA enterovirus with 3 subtypes offering no cross-immunity
Very stable in food and water; multiplies in throat and intestinal mucosa
Usually asymptomatic or brief, mild illness. Viremia sometimes occurs and persists as virus enters CNS causing paralytic polio (rare)
73
Describe preventative measures against Polio
Two types of vaccine:
IPV is dead strain and injected (U.S.)
OPV is live-attenuated and taken orally - high risk of reversion leading to active polio infection. It is cheaper to make and administer and is used in developing countries
74
Describe Ebola in terms of genome, reservoir, transmission, characteristics, and potential treatment
Negative(-) strand RNA virus with ~80% mortality rate
Reservoir: fruit bats
Transmission: direct-contact with Ebola victim, body fluids, or clinical samples
Characteristics: internal hemorrhage
No treatment available; potential treatment could be antibodies from survivors of Ebola
75
What are symptoms and complications of Zika?
Fever, rash, joint pain, conjunctivitis
Complications: GBS, microcephaly
76
Describe modes of transmission for Zika
Primarily through Aedes mosquitoes, the same kind that spread dengue and chikungunya
Also spread from mother-to-child, through sexual contact, or through blood transfusions
77
Prions are misfolded and highly stable; their mode of disease production is still not well understood. What is the current accepted model of disease production by prions?
PrP(sc) causes PrP(c) to CHANGE ITS CONFORMATION to the abnormal form; newly produced PrP(sc) molecules convert other normal molecules to abnormal forms, causing NEURODEGENERATIVE DISEASE
78
What is the most common form of TSE in humans?
CJD
79
Generally, in an infection caused by a DNA-containing virus, the host animal cell supplies all of the following except:
A. RNA polymerase
B. Nucleotides
C. DNA polymerase
D. tRNA
C. DNA polymerase
80
True or false: co-infection with HIV and HHV-8 can greatly promote the development of cancer in AIDS patients
True
81
True or false: hepatitis can be caused by cytomegalovirus and Ebstein-Barr virus
True
82
Women of childbearing age should be vaccinated against:
A. Cytomegalovirus
B. Varicella virus
C. Rubella virus
D. Ebstein-Barr virus
C. Rubella virus
*We do not have a vaccine for Cytomegalovirus or EBV. Varicella in pregnancy would be treated with Acyclovir
83
Which of the following is a prion disease of humans associated with cannibalism?
A. CJD
B. Kuru
C. CJD and Kuru
D. None of the above
B. Kuru
84
Using a homemade saline solution for contact lenses can result in:
A. Acanthamoeba keratitis
B. Trachoma
C. Ophthalmia neonatorum
D. Inclusion conjunctivitis
A. Acanthamoeba keratitis
85
Trypanosoma brucei is transmitted by:
A. Tsetse fly
B. Body lice
C. Houseflies
D. Head lice
A. Tsetse fly
86
Chaga's disease is caused by:
A. Toxoplasma gondii
B. Trypanosomiasis cruzi
C. Plasmodium vivax
D. Leishmania donovani
B. Trypanosomiasis cruzi
87
Anopheles is the vector for the disease:
A. Babesiosis
B. Schistosomiasis
C. Malaria
D. Swimmer's itch
C. Malaria
88
Which organism is a flagellate protozoan that is able to attach firmly to a human's intestinal wall?
A. Giardiasis lamblia
B. Entamoeba histolytica
C. Cyclospora cayetanensis
D. Cryptosporidium hominis
A. Giardia lamblia
89
What organism produces cysts that contaminate food and water and cause dysentary?
A. Cyclospora cayetanensis
B. Giardia lamblia
C. Entamoeba histolytica
D. Asergillus flavus
C. Entamoeba histolytica
90
The only protozoan that causes an STI, which affects mostly women is:
A. Trichomonas vaginalis
B. Gardnerella vaginalis
C. Mycoplasma hominis
D. Haemophilus ducreyi
A. Trichomonas vaginalis
91
Which stage of the plasmodium protozoan infects the RBCs of humans?
A. Schizont
B. Merozoite
C. Sporozoite
D. Gametocyte
B. Merozoite
92
Currently the most promising method to control malaria is:
A. Antibiotics
B. Vaccine
C. Bed nets
D. Chloroquine
C. Bed nets
93
Why are protists considered difficult to treat?
They are eukaryotic, so differentiating treatments between animal cells and their cells is difficult
94
Euglenozoa are hemoflagellates associated with which two protozoan diseases?
Trypanosoma cruzi: Chaga's disease
Trypanosoma gambiense and Trypanosoma rhodesiense: African sleeping sickness
95
Trypanosomes have a unique appearance under the microscope; they are large and move in a spiral-twisting motion using flagella. What is an important virulence factor of trypanosomes?
They have the ability to undergo antigenic variation by changing their protein coat (thick glycoproteins layer coating cell wall) which allows them to evade the immunologic response and we cannot develop a vaccine
96
What are the vectors for african sleeping sickness and chaga's disease?
African sleeping sickness: tsetse fly
Chaga's disease: kissing bug
Reservoirs include cattle and other animals
97
Involvement of what system makes the treatment of African trypanosomiasis difficult?
CNS, because arsenic must be used to allow compounds across the blood brain barrier
98
What is the difference between transmission of African sleeping sickness and Chaga's disease?
African sleeping sickness is caused by the bite of the tsetse fly (metacyclic trypanomastigotes present in salivary glands of fly)
Chaga's disease is caused by the kissing bug defecating into its bite, where the trypanosome moves through the bloodstream, enters cells, and becomes obligate intracellular parasite
99
Leishmaniasis is caused by flagellated protists and can be transmitted by what means?
Sand flies or Parentaral route - blood transfusions causing cutaneous infection
Reservoir is mammals
100
What is unique about the life cycle of Leishmania parasite?
Injected by sandfly as promastigote which is then phagocytized by host macrophages where it transforms into amastigote and multiplies
Sandfly picks up these macrophages with blood meal; amastigotes transform into promastigotes in midgut of fly
101
How do Entamoeba and acanthamoeba move?
Pseudopods, or false feet typical of amoeba
102
What organ system gets damaged by Entamoeba histolytica?
Small intestines
103
What mode of transmission is used by Entamoeba histolytica?
Fecal/oral, typically vehicle involved
104
Entamoeba histolytica is an obligate intracellular parasite causing what?
Amoebic dysentary (bloody diarrhea)
105
Amebic dysentary infection is caused by what?
Ingestion of mature cysts from fecally contaminated food, water, or hands; or from fecal exposure during sexual contact
106
What is the etiological agent of malaria?
Plasmodium (four species - each cause different degree of severity)
107
What is the method of transmission for malaria?
Female anopheles mosquitos
108
What protozoan disease is associated with transmission from animal reservoirs, recreational water, and daycares by ingestion of cysts?
Cryptosporidiosis
109
Cryptosporidium is concerning for what population?
Immunocompromised; AIDs and HIV patients
110
What method of movement does Giardia lamblia use?
Multiple flagella found on the end of the organism
111
How do people become infected with giardiasis?
Drinking fresh water that has become contaminated
112
Describe the motility of toxoplasma Gondi
Apicomplexan (nonmotile)
113
What is the reservoir and method of transmission of Toxoplasma gondii?
Reservoir: wild rodents, birds, small mammals
Transmission: fecal/oral from infected animals, cat litter; also by ingestion of undercooked meat
114
Describe the life cycle of Toxoplasma gondii
Immature oocyst is shed in cat feces which then undergoes sporogony and matures to contain sporocytes which contain sporozoites - these can be transferred to humans by a variety of ways (cat litter, mice, food)
Sporozoites from ingested oocysts invade animal tissue and develop into bradyzoites within tissue cysts or into tissue-invading tachyzoites
115
The unicellular form of fungi is ________; the multicellular form is ________
Yeast; mold
116
What characteristic feature of fungi is important in identification?
Sexual and asexual spores
117
How are fungal spores different from bacterial spores?
Fungal spores are used for reproduction. They are not like bacterial spores in that they are not resistant to things like UV light, chemicals, heat, etc.
118
Unicellular fungi can divide symmetrically by _______, or asymmetrically by __________
Symmetrically = fission
Asymmetrically = budding
119
Pathogenic dimorphic fungi are yeastlike at ______ temperature and mold-like at _______ temperature
Yeastlike at body temperature (37 C)
| Mold-like at room temperature (25 C)
120
Which of the fungal diseases is known for being an obligate intracellular parasite?
Microsporidia
121
Which fungal disease involves insertion of the polar tubule and is dangerous for AIDS/HIV patients?
Microsporidia
122
Where are systemic mycoses found?
Deep within the body (oftentimes due to inhalation)
123
Where are cutaneous mycoses found?
Hair, skin, and nails
124
What are opportunistic mycoses?
They care caused by normal microbiota or environmental fungi and may be seen as nosocomial infections, or when they are not kept in check by other microbes
125
Describe blastomycosis in terms of dimorphism (Y/N), mode of transmission, and symptoms
Blastomycosis is dimorphic
Systemic transmission (inhalation)
Spreads to skin causing cutaneous ulcers and abscesses
126
Coccidiomycosis is diagnosed by demonstration of what characteristic?
Large spherule found in patient sample
127
Cocciodiomycosis is dimorphic and prevention involves avoiding exposure to ______
Dust
128
Which of the fungal diseases has CNS involvement, since it leads to meningitis?
Cryptococcosis
129
What diagnostic characteristic is looked for when diagnosing cryptococcosis?
Encapsulated yeast - the capsule allows the organism to avoid phagocytosis by alveolar macrophages in the lungs
130
What is the difference between the transmission of cryptococcosis and histoplasmosis?
Cryptococcosis is inhaled from pigeon droppings, whereas histoplasmosis is associated inhalation of dirt/dust that was fertilized with with bird or bat droppings
Note that birds cannot be hosts of histoplasmosis because it requires a particular body temperature
131
What are the common hosts of histoplasmosis?
Humans and bats
132
Describe the following cutaneous mycoses in terms of where they are found
```
Tinea capitis
Tinea pedis
Tinea unguium
Tinea cruris
Tinea barbae
Tinea corporis
```
```
Capitis = scalp hair
Pedis = athlete's foot
Unguium = nailbed
Cruris = jock itch
Barbae = beard hairs
Corporis = smooth or bare parts of skin
```
133
Which of the fungal diseases is a class I known carcinogen and causes the lungs to fill with mycelia?
Aspergillosis
134
What type of fungal infection is aspergillosis?
Opportunistic
135
Which of the opportunistic fungal infections can be sexually transmitted?
Candidiasis
136
True or false: diagnosis of candidiasis is difficult and there are no satisfactory treatments
True
137
Which of the fungal diseases is NOT found more often in immunocompromised patients?
Blastomycosis
138
What are the reservoirs of microsporidia?
Domestic and feral animals
139
Which of the fungal diseases occurs almost exclusively in immunocompromised hosts?
Pneumocystis pneumonia (PCP)
140
Most systemic mycoses are acquired from:
A. Insect vectors
B. Puncture wounds
C. Inhaling spores
D. Contact with bodily fluids
C. Inhaling spores
141
Which of the following is NOT caused by a protozoan?
A. Cryptococcosis
B. Sleeping sickness
C. Cryptosporidiosis
D. Giardiasis
A. Cryptococcosis
142
In humans, cryptococcus grows as a:
A. Mold
B. Yeast
C. Dimorphism
D. Mycelium
B. Yeast
143
Vaccines are not effective against trypanosomiasis because:
A. The organisms are obligate intracellular parasites, therefore are never exposed to the immune system
B. The organism is only weakly antigenic
C. The organism can change its protein coat and thereby evade the immune response
D. All of the above
C. The organism can change its protein coat and thereby evade the immune response
144
True or false: Candida albicans is normally found in the vagina but does not usually cause disease because of the acidic pH created by the lactobacilli prevents their overgrowth
True
145
What is one of the most common antifungal treatments and how does it work?
Amphotericin B - binds sterols in membranes
146
Tamiflu is an anti-influenza agent that shortens the course of the flu, what is its mechanism of action?
Neuraminidase inhibitor
147
What is the mechanism of action of acyclovir?
Inhibits herpes virus DNA polymerase
148
What is the prodrug form of acyclovir?
Valacyclovir
149
What are the 3 targets of HIV drugs?
Reverse transcriptase inhibitors (nucleoside and nonnucleoside)
Protease inhibitors
Fusion inhibitors
150
Chloroquine and Mefloquine are used to treat ________
Malaria
151
__________ is the predominate form of food spoilage for foods made up primarily of carbohydrates. It works by degrading the carbs by ___________
Mold; hydrolysis
152
__________ is the predominate form of food spoilage for foods made up primarily of proteins or fats. Its primary mechanism is ___________
Bacterial growth; putrefication
153
A low pH favors what type of food spoilage?
Yeast and mold
154
In terms of antimicrobial substances, _______ exists in cow's milk and eggs
Lysozyme
155
Do lower or higher temperatures slow microbial growth?
Lower
156
Does lower or higher humidity promote bacterial growth?
Higher humidity
157
In terms of atmosphere, does high or low oxygen content promote microbial growth? What discovery did this lead to?
High oxygen promotes microbial growth, which led to the discovery of shrink wrapping foods for freshness
158
How does adding nitrites act as a food preservative?
Nitrites prevent the germination of any spores that are present
It is not meant to control microbial growth in general, it is specific for spore germination (prevents things like botulism)
159
High hydrostatic pressure works to preserve some foods without significantly altering their temperature; it is highly detrimental to the cell _______ and is effective at eliminating ___________ microbes
Membranes; eukaryotic
160
High hydrostatic pressure is not effective at eliminating ______________ microbes due to their _______________
Gram-positive; thick peptidoglycan content
161
Define food-borne infection and give possible sources
Ingestion of a pathogen, followed by growth, tissue invasion, and/or release of toxins
Possible sources: raw foods like sprouts, raspberries, and seafood
162
Which food-borne bacteria is gram-negative, causes fever, and is associated with poultry, shellfish, green onions, lettuce, mushrooms, potatoes, peppers, and spinach?
C. jejuni
163
Staph aureus, Bacillus cereus, Clostridium perfringens, and Clostridium botulinum all have what in common?
Gram-positive
164
What gram-positive food-borne infection is a cause for concern in pregnant women, the young and old, and immunocompromised individuals? Hint: it was responsible for the largest meat recall in the US and at-risk people should not eat soft cheese, refrigerated smoked meats, deli meats, or under-cooked hot dogs
Listeriosis
165
Define food-borne intoxication and give examples
Ingestion of toxins in foods in which microbes have grown; produce symptoms shortly after food is consumed because growth of disease-causing microorganism is not required
Examples: staphylococcal, botulism, Clostridium perfringens, B. Cereus
166
The majority of fermented milk products rely on _____________ bacteria which are gram-positives that tolerate acidic conditions. They are non-spore forming, aerotolerant, and strictly fermentative
Lactic acid
167
What generalized three steps produce chocolate flavor?
Fermentation, drying, and roasting
168
What are the 2 primary acids produced during cocoa fermentation and which one is responsible for most of the chocolate flavor?
Lactic acid and acetic acid
Acetic acid penetrates and activates hydrolytic enzymes leading to flavor development
169
In order of increasing time cocoa is fermenting, name the byproducts. Name the byproduct that is at a steady low state throughout the process
Yeast, Lactic acid bacteria, acetic acid, spore-forming bacteria
Filamentous fungi are at low level throughout
170
Which byproducts of cocoa fermentation contribute to off-flavor (bad chocolate flavor)?
Spore-forming bacteria (Bacillus species) and filamentous fungi
171
Do the following increase or decrease throughout the fermentation process?
```
Sucrose
Citric acid
pH
Ethyl alcohol
Acetic acid
```
```
Sucrose decreases
Citric acid decreases
pH increases
Ethyl alcohol increases
Acetic acid increases
```
172
Why is yeast growth during fermentation not surprising?
Acidic pH (4-6) and high sugar content at the start of fermentation are conducive to the growth of yeast
173
What byproduct of cocoa fermentation plays a role in ethanol production, breakdown of citric acid (increased pH), and the production of organic acids, volatiles, and pectinolytic enzymes?
Yeast
174
Conditions generated by yeast favor the growth of ...
Lactic acid bacteria
175
Aeration of the fermentation mass favors _____ bacteria. Oxidation of ethanol is key!
Acetic acid
176
Which two probiotics are credited with helping to minimize lactose intolerance, improving general intestinal health and balance, lowering serum cholesterol, and potential anti-tumor activity?
Lactobacillus acidophilus and Bifidobacterium
177
Genetic engineering involves the deliberate modification of an organism's genetic information by directly changing the sequence of nucleic acids in its genome using _________________ technology
Recombinant DNA
178
What are the 4 steps in generating recombinant DNA?
1. Isolate DNA to be cloned
2. Use a restriction enzyme or PCR to generate fragments of DNA
3. Generate a recombinant molecule by inserting DNA fragments into a cloning vector
4. Introduce recombinant molecule into new host which expresses the gene
179
What key development in recombinant DNA technology recognizes and binds specific sequences in DNA known as recognition sites, then cleaves DNA at that site or a defined distance from it?
Restriction enzymes
180
cDNA synthesis involves synthesis of a double stranded DNA from ______ using __________
mRNA; reverse transcriptase
181
Gel electrophoresis is used to separate molecules based on their ________ and __________ using agarose or acrylamide gels
Charge; molecular weight
182
DNA is _______ and ______ charged; it migrates from the ________ to the _______ end of the gel
Acidic; negatively; negative; positive
183
What is the term for the method of amplifying a specific segment of a DNA molecule within a complex mixture of DNA?
Polymerase chain reaction
184
What 4 things are contained within a PCR reaction mix?
Primers
Target DNA
Thermostable DNA polymerase
dNTPs
185
What type of cloning vector is most commonly used?
Plasmids
186
What type of cloning vector can carry the largest DNA inserts?
Artificial chromosomes, specifically YACs
187
What is the biggest reason that YACs are chosen instead of BACs as vectors for creating recombinant DNA?
YACs are yeast, so they are eukaryotic and are able to maintain/recognize post-translational modification that happens in eukaryotic cells, making it a better model system than bacteria
188
What are the 3 requirements for a DNA vector?
An origin of replication
A selectable marker
A multi cloning site or polylinker
189
The Blue-White screen allows you to more easily find genes of interest. When looking at the resulting screen transformants, how do you tell which colonies contain our recombinant plasmids?
They appear white!
190
On the blue-white screen, what are the blue colonies?
Original plasmids, they do not contain the recombinant plasmids of interest
all colonies on the plate are ampicillin resistant
191
What type of cloning vectors are engineered genomes previously modified to include restriction sites?
Phage vectors (These have undergone lysogeny!!)
192
What is the difference between the genomic library and cDNA library, and how is each one useful?
Genomic library contains DNA from nucleus - contains everything in genome
cDNA starts with mRNA, so it only includes genes that are being expressed - gives you an idea of which genes are on/off
193
What must recombinant genes have so that they are recognized by the host RNA polymerase?
A promoter
194
During His-tagging, why is the buffer wash step so important?
It gets rid of all the nonspecific, unbound proteins as well as other cellular material
195
During His-tagging, how is the purified protein of interest released from the column?
A solution of Imidazole
196
What are RNAi's?
RNAi = interfering RNA's which are short, mirror-image fragments recognized by cellular enzymes, signaling degradation of RNAi and anything similar to it
197
What is the basis of CRISPR?
RNA is used as a guide to bring a nuclease to a specific DNA sequence to alter it
198
What is the difference between RNAi and CRISPR technology in terms of what is being altered?
RNAi's alter gene expression (RNA)
CRISPR alters the genes themselves (DNA)
199
The CRISPR associated (cas) gene operon contains _____ and ______
Tracr RNA and the CRISPR array
200
What are the two putative nuclease domains associated with cas9?
HNH and RuvC
201
TracrRNA is essential for maturation of crRNA by _____ and ________
Cas9; ribonuclease III
202
What type of compounds are used for emulsification, increasing detergency, wetting and phase dispersion, and solubilization?
Biosurfactants
203
True or false: biosurfactants are important in oil spill recovery, and may also have antibacterial/antifungal/antiviral properties
True
204
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Movement of charged molecules in an electrical field, which is used to separate nucleic acid fragments for recombinant DNA work?
A. Reverse transcripatase
B. Southern blotting
C. Electrophoresis
D. Plasmaphoresis
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C. Electrophoresis
205
The thermostable enzyme most commonly used in PCR is reverse transcriptase. True or false?
False
206
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In order to express eukaryotic genes in a bacterium, the ____ must first be removed
A. Introns
B. Exons
C. Enhancers
D. 3' poly A sequence
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A. Introns
207
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Recombinant DNA technology does not rely on which of the following enzymes?
A. Restriction endonucleases
B. RNA methylase
C. DNA ligase
D. Reverse transcriptase
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RNA methylase
208
Restriction endonucleases in bacteria may have evolved in order to
A. Carry out natural genetic engineering
B. Protect the bacteria from infection by viruses
C. Use nucleic acids as food (energy) source
D. All of the above
B. Protect the bacteria from infection by viruses
209
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Complementary DNA (cDNA) probes are produced using
A. Restriction endonucleases
B. RNA polymerase
C. DNA ligas
D. Reverse transcriptase
```
D. Reverse transcriptase
210
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A ______ is a DNA molecule used in hybridization reactions to detect the presence of a particular gene in separated DNA fragments
A. Plasmid
B. Vector
C. Probe
D. Blot
```
C. Probe
211
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Restriction endonucleases are produced by
A. Fungi
B. Bacteria
C. Protozoa
D. Plants
E. all of the above
```
B. Bacteria
212
The production of large quantities of a particular DNA sequence is known as gene _______.
Amplification
213
The three steps that take place in each cycle during PCR occur in which order?
A. DNA annealing, denaturation, and synthesis.
B. DNA denaturation, annealing, and synthesis
C. DNA synthesis, denaturation, and annealing
D. None of the above
B. Denaturation, annealing, synthesis
214
Which of the following is NOT true of cloning vectors?
A. They usually contain multicloning sites or polylinkers
B. They contain at least two origins of replication
C. They can be replicated within an appropriate host
D. All of these are true of cloning vectors
B. They contain at least two replication origins
215
Plasmid vectors often contain ______ genes that can be used to screen for recombinants
Antibiotic resistance
216
Antibiotics incorporated into the culture medium can do what?
Select against organisms that have not incorporated the plasmid.
217
T/F promoters for genes that code for proteins can be isolated from a cDNA library
False
218
T/F some plasmid vectors have incorporated the regulatory sequences of the lac operon so that the expression of the recomnbinant gene can be induced at the appropriate time
True
219
What biofuel can be produced from degradation of plant starches in corn by amylases and amyloglucosidases, followed by microbial fermentation of sugars?
Ethanol
220
What are some disadvantages to Ethanol use?
Drives up production of food prices
Absorbs water and can't be shipped through existing pipelines
Less energy in its bonds than other molecules
Not carbon-neutral
221
What is an advantage to using ethanol as a biofuel?
Ethanol can be used directly or it can be added to existing petroleum-based fuels
It can also be made using crop residues (waste material) so that food production costs don't increase
222
What is an advantage to hydrogen gas as a biofuel?
It has 3x more potential energy per unit weight than gasoline, making it the highest energy-content fuel available
223
What are the two biggest problems associated with hydrogen gas as a biofuel?
It is flammable, so the biggest problems are storage and distribution
224
How might hydrogen gas be produced as a biofuel?
It can be produced as a direct product of fermentation using hydrogenase and nitrogenase enzymes
225
When making hydrogen gas, why does production slow down as you get more product?
Negative feedback mechanism
226
The _____________ is produced during sporulation of Bacillus thuringiensis (Bt) as an intracellular protein toxin crystal which acts as a microbial ________ for specific groups of insects
Parasporal body; insecticide
227
The Bt toxin binds to phospholipids and inserts into the membranes of cells in the ___________ pH of the insect ________
Alkaline; hindgut
228
After Bt toxin causes aggregation and pore formation in the cells of the insect hindgut, there is efflux of ______ ion and ________, which disrupts the ability to form action potentials. This leads to gut _______, starvation, and __________
Potassium, ATP, paralysis, explosion
229
Why are products treated with Bt not dangerous to humans?
The Bt toxin is specific to the alkaline pH of the hindgut of certain insects, it would not activate in the human body pH and it would not be specific to our cells
230
What part of the multiple tube fermentation test for the sanitary analysis of water determines the MPN?
The presumptive step (step 1)
231
What indicates a positive result for the presumptive step of the multiple tube fermentation test?
Phenol red broth turns yellow and gas production is seen
232
What process uses microbes to transform toxic molecules to nontoxic degradation products and what is an example?
Bioremediation
Ex: Reductive dehalogenation
233
During bioremediation, it is necessary to supply ________________ at the site, such as nitrogen and phosphorus so that co-metabolism can occur
Limiting factors
234
What type of microbes would you add to an area that has experienced an oil spill?
Microbes that naturally produce surfactants
235
What two organisms have a limiting effect on surfactant-producing microbes added after an oil spill?
Phage-mediated lysis and protozoan predation
236
After surfactant-producing microbes have been added to an oil spill and primary oil degradation has occurred, the degradation intermediates are taken up by what?
Secondary consumers
237
Describe the life cycle of plasmodium
1. Mosquito injects sporozoites (infectious form)
2. Sporozoites become schizont, then merozoites in the liver hepatocytes
3. Merozoites infect RBCs and are released when RBC ruptures
4. Merozoites become trophozoites then mature gametocytes
5. Gametocytes are ingested by mosquito
238
What is the infectious form of malaria in the plasmodium life cycle?
Sporozoites
239
What form of plasmodium is present in human hepatocytes?
Merozoites
240
A ____-strand viral genome can be used right away, but a _____-strand viral genome needs to be transcribed first
+ strand (sense)
- strand (antisense)
241
3 examples of viruses with latent infection
HIV, shingles, hepatitis
242
What type of drug targets the maturation of HIV?
protease inhibitor
243
Which herpes virus is the biggest pregnancy concern
CMV
244
Which forms of herpes are carcinogenic?
EBV, HHV8, CMV
245
True or false: HPV has over 150 strains, but not all are oncogenic
true
246
mode of transmission for polio
fecal-oral
247
Of all the viruses, which ones have the greatest pregnancy concerns?
```
CMV
Rubella
Zika
HIV
HSV2
```
248
Differentiate the different causes of CJD:
Familial
Sporadic
Iatrogenic
Variant
```
Familial = genetic
Sporadic = Unknown cause
Iatrogenic = surgery/transplant
Variant = consumption of contaminated meat
```
249
Differentiate between coccidiomycosis, cryptosporidium, cryptococcosis, and cyclospora in general
Coccidiomycosis and cryptococcosis are fungal diseases
Cryptosporidiosis and cyclospora are protozoan diseases caused by ingestion of cysts
250
What are the 2 opportunistic fungi we learned about?
aspergillosis and candidiasis (thrush)
251
what causes pneumocystis pneumonia?
microsporidia
252
In protists that cause diarrhea, what specifically causes the diarrhea?
ingestion of cysts
253
What 4 protists cause diarrhea?
Giardia
Entamoeba histolytica
Cryptosporidium
Cyclospora
254
Are any of the fungi that we learned about vector borne?
NO
255
What is the one virus we learned that is vector-borne?
Zika
256
What 4 protozoan diseases are vector-borne?
Malaria
African Sleeping Sickness
Chagas Disease
Leishmaniasis
257
anemia results from which vector-borne protozoal disease?
malaria
258
A women presents for her annual physical exam and while doing her GU exam you see that she has what is known as a "strawberry cervix", what STI does this woman have?
trichomoniasis
259
What pH is favored by bacteria?
neutral
260
The position of a multi-cloning site is located within a ______ gene for the blue-white screen, which has beta-glucosidase enzyme activity and provides a chromogenic substrate for our bacteria
lacZ
261
Where does Bt toxin come from?
Bacillus thuringiensis
262
What is Bt toxin for/how is it beneficial?
It provides an insecticide that does not accumulate in the environment
263
How is Bt toxin activated?
By the alkaline hindgut of the insect followed by proteolysis
264
What color do gram positive cells stain?
purple
265
What color do gram negative cells stain?
pink or red
266
Which type of bacterial cell has a thicker layer of peptidoglycan and techoic acids in its cell wall?
Gram positive
267
Which type of bacterial cell has a thinner peptidoglycan cell wall and includes an outer membrane?
Gram negative
268
Which type of bacterial cell tends to be more resistant to antibiotics?
gram negative
269
Since bacterial cells replicate by binary fission, what are some possible sources of genetic variation?
- Mutation
- Horizontal gene transfer through conjugation
- Transduction
- Transformation
270
```
Which of the following is not a method of genetic variation used in bacteria?
A. Mutation
B. Opsonization
C. Transduction
D. Transformation
```
B. Opsonization
271
What is unique about prokaryotic transcription and translation as it compares to eukaryotic?
Prokaryotic transcription/translation all happens simultaneously since there are no organelles, everything is located in the cytoplasm
272
In terms of viral genome integration, or __________, these strains are often pathogenic because ________ has occurred
lysogeny; transduction
273
Define the symbiotic relationship: Commensalism
One organism benefits while the other is unaffected/unharmed
274
Define the symbiotic relationship: Mutualism
Both organisms benefit
275
Define the symbiotic relationship: Parasitism
One organism benefits at the expense of the other (host is harmed)
276
Functions of lysozyme as an antimicrobial secretion
Hydrolyzes bond connecting sugars in peptidoglycan
277
```
Which host defense is more effective against gram positive bacteria than gram negative bacteria?
A. Mucus
B. Sebum
C. Gastric juice
D. Lysozyme
```
D. Lysozyme
Because of thicker layer of peptidoglycan, it will have a greater impact -- gram negative are protected by outer membrane
278
What are some mechanisms for drug resistance?
Efflux pumps
Mutation in target protein
Degradation
Enzymatic inactivation
279
What is an example of a drug target for enzymatic inactivation?
beta-lactamases for penicillin
280
Describe endotoxins in terms of their source, metabolic product, chemical make-up, ability to cause fever, ability to be neutralized by antitoxin, and magnitude of LD50
```
Source: gram-negative
Metabolic product: present in LPS of outer membrane
Chemistry: lipid
Fever? YES
Neutralized by antitoxin? NO
LD50: relatively large
```
281
Describe exotoxins in terms of their source, metabolic product, chemical make-up, ability to cause fever, ability to be neutralized by antitoxin, and magnitude of LD50
Source: mostly gram-positive
Metabolic product: by-products of growing cell
Chemistry: protein (soluble, heat-labile)
Fever? NO
Neutralized by antitoxin? YES
LD50: small (among the most lethal substances known)
