Introduction to mycology, virology, parasitology Flashcards by Ashlee Tran

How are fungi different from plants and animals?

Presence of cell wall

No chlorophyll; does not obtain energy from photosynthesis

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How do yeast differ from moulds

Yeast: unicellular
Moulds: mycelial growth of tubular filaments; hyphae

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What is a dimorphic fungus?

depending on environment; can exist either as yeast or mould

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What media is used for growing fungi?

Sabouraud’s agar

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Why are oranges spoilt by mould rather than bacteria?

Environment of an orange suits fungi rather than bacteria; acidic, moist, aerobic

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List the types of asexual spore of fungi

1- sporangiospores (sporangio-) 
2- Chlamydospores (chlamydo-)
3- Conidiospores
(Conidio-) 
4- Arthrospores (Arthro-) 
5- Blastospores (Blasto-)

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List the four stages of fungal sexual spore formation

1- Dikaryotic: Cells of + thallus and – thallus fuse
2- Diploid: After several hours / years/ centuries nuclei fuse
3- Meiosis of nucleus restores haploid state
4- Haploid nucleus partitioned into + and - spores

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List three types of fungal sexual spores

1- Zygospores (Zygo-)
2- Ascospores (Asco-)
3- Basidiospores (Basidio-)

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Name one dermatophyte that causes tinea.

M. Gypseum

T. Mentagrophytes

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Sporotrichosis is caused by which fungi?

Sporothrix Schenckii

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Systematic mycoses are caused by which fungi?

1- Histoplasmosis (H. capsulatum)
2- Blastomycosis (B. dermatitidis)
3- Coccidiodomycosis (Coccidioides immisits)
4- Paracoccidoidomycosis (Paracoccidioides brasiliensis)

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Candidosis, cryptococcosis and pneuosytis pneumonia are diseases caused by opportunistic fungi. (T or F)

True

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Mycotoxins contaminate approximately 25% of foods worldwide, however do not usually cause disease, why?

Rarely appear at dangerous levels.

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Why can’t viruses be grown on artificial media?

Cannot live independently

Dependent on hosts to reproduce

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What is the main feature of viruses that is used to classify them?

Presence of DNA or RNA

Enveloped or non-enveloped

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What two main viral symmetries do viruses causing human diseases have?

Most human diseases caused by viruses have a icosahedral or helical symmetry

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What two ways that viruses can cause disease?

1- Replication within host cell; causes direct damage of the cell
2- Host defences are weakened as it attempts to fight and remove the virus

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List the stages of viral infectivity

Mild
Latent
Severe
Chronic 
Oncogenic 
Teratogenic

List two methods of viral control

1- Heat
2- Disinfectants
3- Vaccines

What is the basic structure of viruses?

Nuclei acid (DNA/RNA)
Capsid (protein coat) & capsomeres (capsid subunits)
Presence/absence of an enevelope

List two modes of transmission of viruses

Direct/indirect contact
Food borne
Air borne
Direct inoculation

List two methods of detecting viruses for diagnostic purposes

Nucleic acid detection (PCR) 
Blood samples (serological tests)

What is a prion?

Proteinaceous infectious particle

What are the names for round and flat worms?

Helminths
Roundworms: Nematodes
Flat worms: Platyhelminths

Trichinella spiralis is found in what type of food?

Pork

What is the common name for cestodia?

Tapeworm

Why are nematode infections so common?

Lack of sanitation, as transmission of nematodes are commonly through faeces.

What are the symptoms of Malaria and why do these symptoms occur?

``` Fever Chills Nausea Headaches Due to lysis (bursting) of RBCs as they are infected with metroziotes ```

What is the main route of infection for parasites? What is an exception?

Faeces, as eggs are passed through faeces and can be transmitted via water. It can also be ingested through food.

What are the general properties of fungi?

- Eukaryote - Unicellular + multicellular - Vary in size - Reproduction: Yeast; budding and moulds spores - Grows on synthetic media - Tolerate high salt, sugar and low pH

What are the levels of classification of fungi?

- Based on thallus; vegetative body of fungus 1- Moulds: mycelial growth of tubular filaments; hyphae 2- True yeasts: unicellular 3- Yeast-like fungi 4- Dimorphic fungi: can exist either and yeast or mould dependent on the environment

What are the benefits of fungi?

``` Food preparation Antibiotic production Enzyme production Acid production Decomposition ```

What the harmful effects of fungi?

Food spoilage Mycotoxin production Unwanted growth on surfaces Animal and plant disease

What are the growth requirements for fungi?

Temp: 25-30 Acidic pH 4-6 Moist Aerobic; requires oxygen

Name the types of fungal infections

``` 1- Superficial infections 2- Skin 3- Cutaneous 4- Sub-cutaneous 5- Systemic mycoses 6- Dermatophycoses 7 -Opportunistic fungal infections ```

How does virus replication occur?

``` 1- Attachment 2- Penetration - Entry into host cell - Uncoats: shedding protein shell 3- Replication of viral genome - Varies; production of viral mRNA - Production of viral proteins 4- Production of structural viral proteins 5- Assembly of progeny virions 6- Release of virions from cell ```

What are examples of pathogenic human DNA viruses?

``` Herpes viruses Adenovirus Papillomavirus Pox viruses Hepadnavirus Polymavirus Parvo B19 ```

What are examples of nematodes

- Tichinella spiralis - Acaris lumbicoides - Trichuris trichiura - Hookworms

What is the method of nematode transmission?

- Egges in faeces | - Water borne

What is an example of platyhelminths?

Trematodia; liver flukes

How are trematodia transmitted?

- Establishes itself in bile duct - Eggs passed into faeces - Eggs passed into water system - Eggs ingested by water snails & larvae released - Ingested by sheep and cattle - Ingested by humans

What is causes fascioliasis and what are its symptoms?

Disease caused by trematodia | Symptoms: fever, tiredness, loss of appetite

What diseases are caused by protozoa?

``` 1- Malaria 2- Giardia lambila 3- Entamoeba Histolytica 4- Cryptosporidium Parvum 5- Tozoplasma gondii ```