Mycology, Virology & Parasitology Flashcards
How do yeasts differ from moulds?
- Moulds: mycelial growth made of branching
tubular filaments called hyphae - True yeasts: unicellular
What is a dimorphic fungus?
- A fungi that can exist either as a mould or a yeast
What media is used for growing fungi?
- Sabouraud’s agar
Why are oranges spoilt by mould rather than bacteria?
- The environment of an orange suits the growth of fungi rather than bacteria (it is acidic, moderate temp, aerobic, moist)
Types of asexual spores of fungi
- Sporangiospores
- Chlamydospores (spores within thickened cell wall of hyphae)
- Conidiospores (naked spores in chains at hyphal tip)
- Arthrospores (fragmentation of hyphae)
- Blastospores (form as buds)
Four stages of fungal sexual spore formation
- Cells of + thallus and – thallus fuse (Dikaryotic
stage) - After several hours / years/ centuries nuclei fuse
(diploid stage) - Meiosis of nucleus restores haploid state
- Haploid nucleus partitioned into + and - spores
Three types of fungal sexual spores.
- Zygospores
- Basidiospores
- Ascospores
Dermatophyte that causes tinea
- M. gypseum or T. mentagrophytes
Sporotrichosis is caused by which fungus?
- Sporothrix schenckii
Systematic mycoses are caused by which fungi?
- Histoplasmosis (H. capsulatum)
- Blastomycosis (B. dermatitidis)
- Coccidiodomycosis (Coccidioides immitis)
- Paracoccidoidomycosis (Paracoccidioides brasiliensis)
Candidosis, crytococcosis and pneumosystis pneumonia are diseases
caused by opportunistic fungi. True or false?
True
Mycotoxins contaminate approximately 25% of foods world wide,
however usually do not cause disease, why?
- They only rarely appear at a dangerous level
Why can’t viruses by grown on artificial media?
- Viruses cannot live by themselves, they require a host cell to reproduce themselves
What is the main feature of viruses that is used to classify them?
- Whether they contain DNA or RNA (enveloped or non enveloped)
What two main viral symmetries do viruses causing human diseases have?
- Most human viral infections are caused by
viruses that have iscosahedral or helical
symmetries
What two ways that viruses can cause disease?
- Replication within the host cell leading to direct
damage of the cell - Host defenses leads to cell damage as it attempt to
clear the virus infected cells
Stages of viral infectivity
- Attachment (to host cell via specific receptor on cell membrane)
- Penetration (entry into host cell, uncoating protein shell)
- Replication of viral genome
- Production of late viral proteins (structural)
- Assembly of the progeny virions
- Release of virions from cell (budding or lysis)
Two methods of viral control
- Heat
- Disinfectants
What is the basic structure of viruses?
- Nucleic acid core (DNA or RNA)
- Capsid (capsomeres)
Two modes of transmission of viruses
- Physical contact
- Food borne
Two methods of detecting viruses for diagnostic
purposes
- Fluorescent microscopy
- Serological tests (blood samples)
Prion
- A proteinaceous infectious particle
Names for round and flat worms
- Nematodes (round)
- Platyhelminths (flat)
Trichinella spiralis is found in what type of food?
- Pig meat
What is the common name for cestodia?
- Tape worms
Why are nematode infections so common?
- Most transmission is through contaminated water
What are the symptoms of malaria and why do these
symptoms occur?
- Fever, chills, nausea, headache
What is the main route of infection for parasites? What is an exception?
- Faecal-oral route
- An exception is malaria, which is through the bloodstream
Ascaris lumbricoides,Trichuris trichiura and Enterobius
vermicularis are what type of helminth?
- Nematodes (roundworms)
