Exam 2 Flashcards
What is mycology?
study of fungi
what groups of organisms are classified as fungi
molds
mushrooms
yeast
true or false fungi are classified as prokaryotes
false
- classified as eukaryotes
which is larger, bacteria or fungi? how big
- fungi –> 4 mcm
- bacteria –> 1 mcm
which organism (fungi or bacteria) has mitochondria and ER present in their cytoplasm?
Fungi
which organism has sterol absent in their cell membrane
bacteria (except mycoplasma)
what is fungi cell wall content
chitin
what is bacteria cell wall content
peptidoglycan
what is the function of spores in both organisms
- in fungi they are used for reproduction
- in bacteria they are used for survival not reproduction
which organisms perform thermal dimorphism
fungi (change structure with heat)
what is the cell wall of fungi composed of
polysaccharides (including chitin)
- marked differently from those found in bacteria
true or false fungi grow best above 25 degrees celsius
false
- thats why not many are pathogenic to humans with 37 degrees body temp
what type of parasites are fungi (obligate or opportunist)
opportunist
why are fungi able to synthesize useful products
large ability to break down a wide range of organic material
providing them with a huge metabolic capability to synthesize products
what products are fungi able to synthesize
Steroids
Organic Acids
Foodstuffs
Antibiotics
Vitamins
Enzymes
SO FAVE
what does opportunistic mean
bacteria can live on their own but are likely to infect hosts with weakened immunity
what does obligate mean
organisms that cannot live without a host
what does facultative mean
can survive in environments with or without oxygen
fungi are mostly saprophytes, what does this mean?
feeding on decaying organic material
why does fungi growth need to be controlled
they’re responsible for spoilage of food and medicines
why are fungi so bad if they rarely infect humans?
because when they do they are usually persistent and difficult to treat
what are the four common form of fungi
- yeats
- yeasts like fungi
- dimorphic fungi
- filamentous fungi
what are the three ways in which fungi asexually reproduce
- growth and spread of hyphal filaments
- asexual reproduction of spores
- simple cell division (budding yeasts)
what are sexual spores of fungi usually resistent to
chemicals
drying
heating
freezing
what is an example of yeasts
- Saccharomyces cerevisiae (baker’s yeast, brewer’s yeast)
- cryptococcus neoformans ( causes lung infection)
how do yeasts reproduce
by budding and binary fission
what is budding
offspring emerges as a bud on side of parents cell and pinches off
how many offspring can a parent cell (yeast) reproduce
24
how do yeast like fungi reproduce
budding but become elongated to form pseudohyphae (elongated filaments)
how many forms do dimorphic forms exist as
2
how do dimorphic fungi grow
as yeasts or filaments
- yeasts at 37 degrees
- filaments below 22 degrees
what is the most important dimorphic fungi
histoplasma capsulatum
- causes disease that manifests from a mild chest infection to a fatal spread through the body
- starling bird shit
true or false bread mold requires light
false
how do filamentous fungi grow
as long, slender, branching filaments called hyphae
what is the structure of hyphae
- divided by branches with walls dividing each hyphae into separate walls
what is mycelium
a compact tuft that hyphae form as they typically grow together above a surface
how do we quantify filamentous fungi
measuring mass
what 3 things make up the cell wall of fungi
what do they do for cell
what happens if any part is broken
- glucosamine polymer chain
- glucans
- proteins
- these things maintain rigidity of cell wall. if they’re broken down the cell becomes leaky and cannot replicate
what types of fungi are rhizopus stolonifer and mucor heiemalis
both members of zygomycetes (lower fungi)
how do rhizopus stolonifer and mucor heiemalis reproduce
by means of sporangiospores
how are rhizopus stolonifer and mucor heiemalis commercially used
they both produce a large number of organic acids and are used in the production of steroids
what organic acids do rhizopus stolonifer and mucor heiemalis produce
fumaric, lactic, citric
what is claviceps purpurea a contaminent of
cereal rye
how are claviceps purpurea commercially important
important source of pharmaceutical products
how do ergot alkaloids contribute to biological activity
- control hemmorhage
- induction of childbirth
- treatment of migraine and headaches
why is aspergillus niger commercially important
spoilage organism
-hay
-nuts
-grain
produces acid
-citric acid
-gluconic acid
fermented products
-sake sauce
-soy sauce
produce enzymes
-proteases
-amylases
-diastase
what does contamination lead to
production of myotoxins which cause liver damage
what do aspergillus cause
disease called aspergillosis –> lung and ear disease
how are pencillium chrysogenum commercially important
best role for its role in production of penecillin
–> natural product penecillin G
- frequent contaminent of food and is seen as green or blue mold
- used in production of fumeric, citric, gluconic, oxalic acids
What are candida albicans?
yeasts like fungi
candida albicans are usually kept in check with other microflora but in what conditions can it overgrow?
antibiotic therapy
long-term steroids
diabetes
immunosuppressive therapy
diet
alcoholism
vitamin deficiency
ALDI DAV
what is thrush
yeast infection of the mouth or vagina
what is caused by filamentous fungi
cause diseases of the skin hair and nails
- affect keratinized area
what are these diseases of the skin referred to as
tinea & dermatomycoses and ringworm
where does the name ringworm come from
tinea corposis- circular lesions on the skin which resemble worm under the skin
what is tinea-pedis
althletes foot
what is one of the most common infectious diseases
althletes foot
how does althletes foot occur
- a single spore initiates infection
- spore germinates and pentetrates stratum corneum
- fungus produces branching septae hyphae
- branching septae hyphae forms athrospores by fragmentation of hyphae
what does the athletes foot infection begin as
cracking or scaling between toes
what is an example of the class of antifungals referred to as polyene macrolides
amphotericin
- broad spectrum
what is polyene macrolides mode of action
bind to membrane ergosterols
what class of anti-fungals inhibits DNA biosynthesis by being incoorporated into fungal RNA –> inhibition of protein synthesis
flourinated pyrimidines
what is an antifungal that inhibits cell division by interfering with microtubule formation in the nucleus
antifungal antibiotics
-ex. griseofulvin
inhibit ergosterol synthesis by inhibition of cytochrome P-450
- clotrimazole
- ketoconazole
Imidazoles
What class of antifungals block fungal cell wall synthesis
echinocandins ex: caspofungin
Are protozoa single-celled or multicellular?
single celled
Are protozoa prokaryotic or eukaryotic?
Eukaryotic
T/F: most protozoa are parasites that can only reproduce inside an animal host
true
Is it hard to cultivate ameba in the laboratory?
no, it is cultivated easily
why are some protozoa difficult to grow in the lab?
they have both human and insect stages in their life cycle –> require complex media supplemented with RBC
what is an example of a protozoa that is difficult to grow in the lab
Plasmodium (AKA malaria)
where are protozoal infection the most common?
tropical countries
why are protozoal infection more common in tropical countries?
tropical temps promote the reproduction of both protozoa themself and their insect vectors
what is the protozoa responsible for Trichomoniasis
Trichomonas vaginalis
what is the protozoa responsible for malaria?
Plasmodium falciparum (responsible for 75%)
what is the protozoa responsible for amoebic dysentery?
Entamoeba histolyticum
what is the protozoa responsible for Trypanosomiasis?
-Trypanosoma brucei (African Sleeping Sickness)
-Trypanosoma cruzi (Chagas Disease - American Sleeping Sickness)
what is the most common protozoal pathogen in industrialized countries?
trichomoniasis
How is trichomoniasis transmitted?
sexual contact
does trichomoniasis infect men or women more?
affect both genders at the same frequency
what do “azole” drugs typically treat and how?
fungi infections by targeting ergosterol synthesis
what are the two “azole” drugs that are used to treat protozoal infections?
metronidazole and tinidazole
What is malaria caused by?
Plasmodium protozoa
what are the four main species of malaria?
-P. falciparum
-P. vivax
-P. ovale
-P. malariae
what parasite related to malaria infects monkeys but could also infect humans?
P. knowlesi
what is the insect vector for malaria?
female anopheles mosquito
T/F: the life cycle of malaria consists of a sexual and asexual cycle
true
where does the sexual cycle of malaria occur?
the female mosquito
where does the asexual cycle of malaria occur?
humans
What are sporozoites?
motile form of parasite
where are sporozoites in the malaria life cycle?
they are introduced into the host following the insect bite and then develop in the liver
what are schizonts?
Cyst-like structures formed by Plasmodium that contains thousands of merozoites
what occurs to schizonts?
they burst and release merozoites
What are merozoites?
daughter parasites of sporozoites
What are trophozoites?
the active, motile feeding stage of a sporozoan parasite
What is an erythrocytic cycle?
malaria parasite found in the blood
what is an exoerythrocytic cycle?
malaria parasite found in the liver
what are the characteristics of P. falciparum?
-48 hr erythrocytic cycle in humans
-produces malignant tertian malaria
-“malignant”: the most severe form of malaria
-“tertian”: fever believed to return every 3 days
What are the characteristics of P. vivax?
-benign tertian malaria
-rarely fatal
-exoerythrocytic forms may persist for many years and cause relapses
what are the characteristics of P. ovale?
-48 hr erythrocytic cycle
-exoerythrocytic stage
-rare
what are the characteristics of P. malariae?
-quartan malaria
-72 hr erythrocytic cycle
-no exoerythrocytic cycle
Patients with what disease are protected from malaria?
Sickle Cell Anemia
how does sickle cell anemia protect against malaria?
-excess production of CO restricts availability of hemoglobin
-APC
Which of the following protozoal infections cause sleeping sickness?
A. Yellow Fever
B. Malaria
C. Trypanosomiasis
D. Athlete’s Foot
C. Trypanosomiasis
what medications are used to treat trichomoniasis?
metronidazole or tinidazole
what medications are used to treat giardiasis?
metronidazole or tinidazole
what medications are used to treat Amoebic dysentery?
metronidazole or tinidazole
what medication is used to treat trypanosomiasis?
pentamidine
drugs used to treat the acute attack of malaria act on…?
the parasites in the blood –> can cure malaria with no exoerythrocytic stage
drugs used for prophylaxis of malaria act on…?
merozoites emerging from liver cells
drugs used for the radical cure of malaria act on…?
parasites in the liver
drugs that act on mosquito gametes help prevent what?
prevent transmission by the mosquito
what drug is used to treat P. falciparum, mixed organisms, or unknown malaria
quinine
what drug is used to treat P malariae, P. vivax or P. ovale
chloroquine
why has the use of drugs for treatment of malaria changed?
developed resistance to chloroquine and other successful early drug combinations
T/F: monotherapy has been largely abandoned in favor or artemisinin-based combination therapy for the treatment of malaria?
true
What are the four reasons antimalarial drugs are used?
-treat acute attack
-radical cure
-chemoprophylaxis
-prevent transmission
what are the characteristics of quinine?
-derived from cinchona bark
-blood schizonticidal drug effective against the erythrocytic forms of all four species
-no effect on exoerythrocytic forms or gametocytes
what are the characteristics of artemisinin?
-derived from herb qinghao
-often only drugs that can effectively treat resistant P. falciparum
what is considered to be the second leading cause of death from parasitic disease worldwide?
amoebiasis (Entamoeba histolytica)
what drugs are used to treat amoebiasis (Entamoeba histolytica)?
metronidazole or tinidazole followed by diloxanide for acute invasive intestinal amoebiasis
what do the drugs used to treat trypanosomiasis depend on?
the disease stage
what drug is used to treat trypanosomiasis in the first stage?
pentamidine and suramin
what drug is used to treat trypanosomiasis in the second stage?
-melasoprol
-eflonithine
-nifurtimox
T/F: Viruses have cellular structure
False, they only have genomic structure (RNA/DNA)
Who/what are susceptible to virus infection?
all cellular organisms
where do viruses grow/reproduce?
inside host cells
what is a free-living virus particle called? (outside the host)
virion
what is in the nucleocapsid of a virus?
-coat (capsid)
-nucleic acid core (DNA or RNA)
what does the coat (capsid) of a virus do?
encloses the nucleic acid
T/F: some virus have a lipoprotein envelope and some viruses do not
true
what are viruses that have a lipid envelope susceptible to?
-drying
-solvents and disinfectants
T/F: viruses that do not have a lipoprotein envelope are not easily treated with chemicals or heat
true
what is the common structure of a virus?
not a true sphere but an icosahedron (comprising 20 triangular sides)
what is an example of a virus with a tail?
bacteriophage
what is an example of a virus that has a structure of long curved or coiled filaments?
Ebola
what is an example of a virus that has a filamentous structure?
tobacco mosaic (helical capsid)
what is an example of a virus that has a structure that resembles a brain?
smallpox
what are examples of DNA viruses?
-herpesviruses (chickenpox, shingles)
-adenoviruses (common cold)
what are examples of RNA viruses?
-influenza
-coronavirus
-retroviruses (AIDS, T-cell, leukemia)
what is an example of a hepadna virus?
Hepatitis B virus
what are the characteristics of adenovirus?
-“common cold”
-non-envelope
-DNA virus (linear ds DNA)
what are the characteristic of Influenza?
-enveloped virus
-segmented viral genome
-hemagglutinin and neuraminidase
What is hemagglutinin?
-protein on influenza that mediates entry of virus into cell
-highly immunogenic
what is hemagglutinin’s immunogenic ability?
-capable of stimulating the immune system
-how immunity to influenza through is developed vaccines
What is neuraminidase?
breaks sialic acid (component of host cell memb.) for the virions incorporation
when does infection of influenza begin?
attachment of the viral hemagglutinin to neuraminic (sialic) acid residues on host cells
what occurs in the infection of influenza after the virus enters the cell?
-the nucleocapsid separates from the envelope and migrates to the nucleus
-activation of viral RNA
what type of illness is influenza?
respiratory
what is the M1 located on the influenza virus?
holds RNA in place
what is the M2 located on the influenza virus?
proton channel (entry of H+ ions)
what are the symptoms of influenza?
-headache
-fever
-cough
-sore throat
-aching muscles/joints
what are the three main types of influenza?
A,B,C
what is the most severe form of influenza?
influenza A
what are the structural characteristics of corona viruses?
-large single stranded RNA genome
-fatty outer envelope
-spikes on outer surface
what is corona viruses named corona viruses?
-crown or “corona” of club-shaped spikes on their surface
how are coronaviruses transmitted?
-coughing
-sneezing
-person-to-person contact
-touching objects containing viral particles
T/F: coronaviruses are rapidly inactivated by 70% ethanol or 90% isopropanol, soaps, detergents, and UV lights
true
What are the steps of conrona virus infecting a host cell?
- binding and viral entry
- release of viral genome
- replication of viral genomic RNA
- transcription of viral RNA
- translation of viral proteins
- assembly of viral particles
- formation of mature virion
what does HIV stand for?
human immunodeficiency virus
what are the characteristics of Retrovirus (HIV)?
-contains two identical copies of the RNA genome
-enveloped
-transcriptase
how does retrovirus weaken a person’s immune system?
destroys important cells that fight disease and infection
what are the three enzymatic activities of reverse transcriptase
- reverse transcriptase activity
- ribonuclease activity
- DNA polymerase
what is the reverse transcriptase activity of reverse transcriptase?
to synthesize DNA from an RNA template
what is the ribonuclease activity of reverse transcriptase?
to degrade the RNA strand of RNA:DNA hybrid
what is the DNA polymerase activity of reverse transcriptase?
to make double-stranded DNA from single-stranded DNA
T/F: viruses have their own metabolic machinery
false
they do not have their own metabolic machinery and will hijack their host’s metabolic process to replicate
how do viruses replicate?
- polypeptide binding site on virus interact with receptors on host cell
- the receptor-virus complex enters the cell through receptor-mediated endocytosis
3.viral nucleic acids use the host machinery to synthesize acids and proteins (this step varies in RNA and DNA viruses)
what are the steps of replication for RNA viruses?
-enzymes within the virion synthesize mRNA from its viral RNA template
-translated by host cell into various enzymes (structural enzymes and RNA polymerase)
what are the steps of replication for DNA viruses?
-viral DNA is transcribed into mRNA in the nucleus of the host cell (uses RNA polymerase of the host cell)
-translation of mRNA in virus-specific proteins
-coat proteins assemble around viral DNA
-virions released by budding or host cell lysis
smallpox can infect who
humans only
HIV can infect who
humans and other primates
vertical transmission
from pregnant mother to baby via breastmilk
horizontal
from one individual to another of the same species not in a parent-child relationship
what virus transmits through transplacental
cytomegalovirus
which virus has transmission at time of birth
hep B, HIV, HPV
Which virus transmits through breast feeding
human T-cell lymphotrophic virus
how do viruses transmit through droplet nuclei
particles expelled into air during sneezing coughing or talking
ex: flu, COVID, respiratory system
how do viruses transmit through the fecal-oral route
primary infection for viruses is gastro-intestinal tract or associated organs. don’t eat shit ???
ex: hep A and polio
what are examples of sexually transmitted disease
HIV/AIDS
What viruses do insect vectors transmit
dengue fever virus, west nile
how is flu transmitted
aerosol droplets, chickens
how is SARS transmitted
aerosol droplets, civet cat
how is encephalitis transmitted
bite of various mosquitos, wild birds
what is direct contact
direct contact with infected patients or contaminated objects in which virus is introduced to skin
ex: warts, and in some cases, blood stream, pox viruses
direct introduction
into the bloodstream
ex: used needles, Hep B, rabies following animal bites
how do viruses usually reproduce once inside human cell vs. a latent virus
usually reproduces and causes the cell to die via lysis and releases new virus particles
BUT
some viruses enter a latent (dormant) state in a small fraction of infected cells and DON’T cause immediate damage but give rise to a persistent infection
What is an example of a latent virus that can reactivate with suitable stimuli causing it to reproduce and kill the cell “normally”
varicella zoster = chicken pox–> shingles
true or false: herpes is a latent virus
true
- cold sores appear following the reactivation of stimulus of exposure to UV
which viruses can cause viral cancers
HPV –> cervical cancer
Hep B and C –> liver cancer
what is the first defense against a virus
barrier function of intact skin
true or false broken skin and mucous membranes are less likely to become vulnerable to attack
false
- if you said true are you okay?
what happens when virus gets inside you
initiation of innate and subsequently adaptive immune system
what two ways can a virus attack the host defense
subversion of the immune response
evasion of immune detection and attack by killer cells
What does subversion of the immune response mean
viruses inhibit IL-1 or TNF alpa that coordinate the innate and adaptive responses
ex: pox virus expresses proteins that mimic cytokine receptors. These pseudoreceptors bind cytokines and prevent them from reaching their natural receptors and thus moderating immune response
What does evasion of human detection and attack by killer cells mean
how once viruses are inside the host cell they can escape immune detection and avoid attacks by cytotoxic t-cells and NK cells
How are viruses able to avoid these immune responses
- interference w/ surface proteins on infected cells making the lymphocytes and NK cells unable to recognize and attack
- interference w/ apoptotic pathway
- adopting baby turkey ploy –> produce MHC markers that body thinks is its own and leaves alone
what does “-vir” mean
antiviral agents
what type of antiviral is abacavir and zidovudine
nucleoside reverse transcriptase inhibitors
What type of antivirals are nevirapine
non-nucleoside reverse transcriptase inhibitors
What type of antivirals are atanzanavir
protease inhibitors
What type of antivirals are acyclovir
Viral DNA Polymerase inhibitors
which drug is a neurominidase inhibitor
oseltamivir (flu)
whuch drug is an M2 ion blocker
ratelgravir
What do reverse transcriptase inhibitors do
Act against reverse transcriptase - an enzyme HIV uses early in the replication cycle to make DNA copies of RNA genome (typified by zidovudine)
what is zidovudine
the first drug to be introduced for the treatment of HIV
- diminishes HIV-associated dementia
what is the down side of using this medication too long
because the virus is a constantly moving target, and resistance develops with long-term use, especially in the later stages of the disease
what are non-nucleoside reverse transcriptase inhibitors
chemically diverse compounds that bind to the reverse transcriptase enzyme near the catalytic site and inactivate it
what drugs are available that are considered NNRTI
efavirenz and nevirapine (related compounds are etravirine and rilpivirine)
What are protease inhibitors
bind to the site where cleavage occurs and their use, in combination w reverse transcriptase inhibitors, has transformed the therapy of aids
- block new HIV from becoming mature HIV
What are fusion inhibitors?
agents that inhibit fusion of HIV with host cells
ex: enfurvitide
What do DNA polymerase do
inhibits viral DNA polymerase and gets incoorporated into DNA to terminate the nucleotide chain
how many times more potent is acyclovir against the herpes virus enzyme than the host enzyme
30x
What are integrase inhibitors
agents that block the virally encoded integrase enzyme that splices the viral DNA into the host genome forming the provirus
what is an example of integrase inhibitor and when is it used
Ex; ratelgravir
- used in the treatment of HIV as part of combination therapy
how is varicella zoster (chix pox and shingles) used in immunocompetent people
orally
how is varicella zoster (chix pox and shingles) used in immunocompromised people
IV
what does prophylactically mean
prevention
When are prophylactic antibiotics given?
in patients who are to be treated with immunosuppressant drugs or radiotherapy and who are at risk of herpes which may lead to reactivation of latent virus
what are neuraminidase inhibitors (flu)
prevents release of intact virions from the host cell
What is neuraminidase?
It is an enzyme that catalyses a cleavage reaction which allows the new viral particles to escape from the host cell and spread infection.
how does one become infected w these
infection of these RNA viruses begin w attachment of viral hemagluttin to neuraminic acid residues on host cells
- viral particle enters by endocytosis
- endosome is acidified following the influx of h+ through the M2 (viral protein) ion channel
- dissambly of virus occurs and RNA enters the host nuclei so replication of virus can occur
what are neuraminidase inhibitors like zanamivir and oseltamivir active against
influenza A and B
which “old” drug effectively blocks the M2 ion channel, inhibiting dissambly of the virus
amantadine
true or false amantadine is effective against influenza A and B
false, only A
What are immunoglobulins?
antibodies directed against the virus envelope and can neutralize certain viruses and prevent their attachment to host cells
what are interferons
they bind to specific ganglioside receptors on host cell
- they induce the production of enzymes that inhibit the translation of viral mRNA –> halt replication
what are immunomodulators
drugs that act by moderating the immune response to viruses or use an immune mechanism to target a virus
what is inosine pranobex
interferes w viral nucleic acid synthesis –> used to treat herpes infection of mucosal tissues or skin
what is tribavirin
a synthetic nucleoside that alters virus nucleotide pools or interfere with the synthesis of viral mRNA
How much histoplasma capsulatum is subclinical and how is it tested?
95% - tests by skin
