Microbiology: exam 3

Describe the lytic cycle of T-even bacteriophages.

(Attachment) attach to the cell mainly bacterial cell (penetration) only nucleic acid is injected into the cell through the hole caused by the tail fibers and enzymes (synthesis) replication of viral nucleic acid and protein and envelope (assembly) spike proteins insert into the cell membrane, the capsid forms around the nucleic acid to form the mature virion. (release) usually by lysis through the membrane.

Review questions in PP "Viruses PartII)

16.

Why should we cook well pork meat? (Trichinelle spiralis)

Because a human could contract trichinosis or "pork worm"

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

What are the three phyla of Algae and their pigment.

Chlorophyta: green algae Phaeophyta: brown algae Phodophyta: red algae

Distinguish between cyst and trophozoite and relate the two terms to bacteria.

Cyst • non-dividing • rigid cell coat • resistant to H20 + dessication • can survive outside of host in most ambient conditions • transmission state relates to bacteria because it can survive outside of the host Trophozoite • dividing (binary fission) • labile cell membrane • disease causing state • cannot survive outside of host related to bacteria because reproduces through binary fission

Describe the basic structure of a virus. What are main characteristics?

DNA or RNA Capsid protein myelin sheath protein coat envelope envelope proteins characteristics: small in size no metabolism of their own noncellular do not absorb nutrients commands the host cell produce virus can be crystallized all of them produce disease

Give an example of DNA virus and RNA virus

DNA virus: Herpes RNA virus: Influenza

Classify them and give one example of pathogenic protozoan for each group.

Diplomonads: giardia lamblia parabasalids: trichomonas vaginalis euglenozoa: trypanosoma amebae: entamoeba apicomplexa: cryptosporidium ciliates: balantidium coli

Give an example of a family, genus, and common name for a virus.

Family: Retroviridae Genus: Lentivirus Common name: HIV

6 main descriptors of fungi

Growth enviornment pH: 5 All molds other than some yeasts are aerobic Can grow in high sugar or salt concentrations (Most fungi are resistant to osmotic pressure) Can grow on structures with low moisture: Require less nitrogen than bacteria Capable of metabolizing complex carbohydrates

Name one virus that carries the enzyme "Reverse Transcriptase"

HIV

List the defining characteristics of fungi. What is their main role in Ecosystem?

Kingdom: fungi nutritional type: chemoheterotroph multicellularity: all, except yeasts cellular arrangement: unicellular, filamentous, fleshy food acquisition method: absoprtive characteristic features: sexual and asexual spores main role in environment decomposers and recyclers:

What are lichens? Describe the role of the fungus and the alga in the lichen

Lichens mutualistic relationship between cyanobacteria and a fungus The alga photosynthesizes, providing carbohydrates for the lichen; the fungus provides a holdfast Lichens colonize habitats that are unsuitable for either the alga or the fungus alone

Define mechanical and biological transmission + example.

Mechanical transmission: vector transfers agent from infected host to suspected host biological transmission: agent develops and/or propagates within the vector,

What is a mass of hyphae

Mycelium

Discuss mycotoxin: ergot and aflatoxin as to their source, their effects.

Mycotoxins are secondary metabolites produced by microfungi that cause disease and death in humans and other animals ergot: an alkaloid produced by fungi of the genus clavicep. can cause hallucinogenic affects in humans source: grows on grains aflatoxin: toxin produced by fungi aspergillus flavus. when ingested can cause mutagenic compound in humans source: grows on grains

Define oncogene and transformed cell.

Oncogene: a gene that could possibly transform a cell into a cancerous cell transformed cell development of new genetic traits after taking in foreign dna material

Important temperatures for dimorphic fungi?

Pathogenic dimorphic fungi are yeastlike at 37°C and moldlike at 25°C

Hyphae:

The branching, threadlike tubes that make up the bodies of multicellular fungi

Differentiate between virus, viroid, and prion.

Virus= Tiny infectious a cellular agent having either DNA or RNA (Does not have a cell, but has a genome.) Viroid= Naked RNA molecule which infects plants Prion= Proteinaceous infectious particle that lacks nucleic acids and replicates by converting similar normal proteins into new prions. (mutation caused protein to have different folding properties)

Classify fungi a) according to the shape (morphology); b). according to sexual spores. Example for each

Zygomycota: Non septate hyphae Sporangiospores Rhizopus Mucor Microsporidia No Hyphae Nonmotile Spores Encephalitozoon Nosema Deuteromycota: fungi imperfecti hyphomycetes Ascomycota: Dimorphic Conida Aspergillus Claviceps Anamorphs: Septate hyphae Dimorphic Conida Epidermophyton Basidiomycota: Septate Hyphae Conida Cryptococcus

Describe how animal viruses are cultured.

by infecting an animal cell with a virus within the culture media in the laboratory

Give some fungal enzymes which make of them "decomposers"

cellulase (breaks down cellulose) (enzymes split many of lignin's chemical bonds, turning it into simple sugars and releasing carbon dioxide into the air.)

The two types of hyphae ( coenocytic and septate)

coenocytic: hyphae (long filaments of cells joined together that make up the "mold" or "flesh like" structure of the fungus) that do not have a septate (cross walls that divide hyphae into cell like units) and are look long and continuous. they have many nuclei. dont form septa between nuclei do form septa at branch points to connect filaments together nutrients flow through coenocytic easier, but more prone to rupture because there's nothing to keep cytoplasm from leaking out usually Zygomycetes. septate: have dividers between cells called septa. the septa have pores between that let cytoplasm and nutrients go through the mycelium when new cells bud at the head of the hyphae, septa dont grow immediately. While the cell is maturing the cell wall grows down into the cytoplasm, forming a septum will close one injured septa to save entire filament Basiodiomycetes and Ascomycetes form septate hyphae.

blastoconidia:

consists of buds coming off the parent cell

Define and differentiate between an intermediate host and a definitive host in parasitic infection and apply these terms to reproductive cycle of Plasmodium malariae .

definitive host: a host in which the parasite reaches maturity and, if possible, reproduces sexually. intermediate host: a host that harbors the parasite only for a short transition period the definitive host is the vector mosquito Anopheles the intermediate host is the human

Coenocytic hyphae:

do not contain septa

What is a dimorphism? Factor directing the dimorphism?

either yeast or mold if they're yeast they produce single cells and multiply by old cells producing daughter cells. factor directing dimorphism is heat (example: penicillin)

Sporangiospore:

enclosed in a sac

Give one of dimorphic fungi and the factor that controls the dimorphism.

example: penicillium marneffei grows as mold at room temperature and yeast at human body temperature

arthroconidia:

fragmentation of septate hyphae

Plasmogamy:

fusion of cytoplasm

Karyogamy:

fusion of nuclei

Describe how bacteriophages are cultured.

grown by infecting bacterial cells with viruses

conidiphore:

he virus is not cleared but remains in specific cells of infected individuals

Discuss four different ways fungi are beneficial for mankind and four different ways fungi can harm mankind.

helpful: produce drugs (alcohol and penicillin) mycorrhizae help plant roots absorb minerals and water from soil (so humans can eventually eat those plants) for food (mushrooms) produce foods (bread and citric acid) harmful: some cause disease (200 out of 100,000) (all fungal infections are called mycosis) kill important plants, costing 1 billion dollars annually food spoilage fungal toxins

What criteria is used for their classification?

locomotion amoebas ciliates sporozoa (non motile) flagellates

Describe their reproductive system. (monoecious, diecious & meaning)

monoecious: having both male and female diecious: male or female reproductive system

What is mycosis? Different types?

mycosis: fungal infection systemic mycoses: fungal infections deep within the body subcutaneous mycoses: fungal infections beneath the skin caused by saprophytic fungi (live in soil and on vegetation) Dermatomycoses: only affect epidermis, hair and nails Superficial mycoses: local to hair shaft and in superficial epidermal cells oppourtunistic pathogen: usually harmless - but can become pathogenic in a host who is seriously debilitated

Differentiate between persistent viral infections and latent viral infections.

persistent viral infections: where the virus is not cleared but remains in specific cells of infected individuals latent viral infections: an infection is dormant

Give an example of a platyhelminth and an example of nematode.

platyhelminth: tapeworms nematode: enoplea

What are defining characteristics used to classify Algae? Role in Ecosystem?

producers in all ecosystems aquatic and marine habitats AKA phytoplankton not a taxonomic group

List the characteristics of parasitic helminthes.

reduced digestive system reduced nervous system reduced locomotion complex reproduction

List few benefits that human get from Algae.

reduces amount of toxic chemicals from water source.

Contrast saprophyte from parasite.

sarophyte: plant, fungus, or microorganism that lives on decaying matter parasite: lives in or on another organism, and lvies by taking nutrients at the host expense

Define and provide an example of latent viral infection.

shingles disease

Septa:

the cells that make up hyphae are divided by these cross sections

chlamydoconidium:

thick-walled spore formed by rounding and enlargement within a hyphal segment

Discuss how a protein can be infectious.(Prion)

through protein misfolding

Differentiate between a tick and a mosquito, and name a disease transmitted by each.

ticks are arachnida and have 8 legs disease: lyme disease mosquitoes are insecta and have 6 disease mosquitoes: malaria

Define arthropod vectors

vectors (like mosquitoes, tick etc) that transmit pathogens while feeding on blood

List the defining characteristics of Protozoa.

vegetative form is trophozoite asexual reproduction by fission, budding or schizogony sexual reproduction by conjugation some produce cysts

Differentiate between a virus and a bacterium.

virus: small in size no metabolism of their own noncellular do not absorb nutrients commands the host cell produce virus can be crystallized all of them produce disease bacteria: larger in size absorb nutrients single celled have their own metabolism can reproduce on their own some are harmless, some are useful, some are disease causing

What is a pseudohyphae? Relate this to Candida albicans's pathogenicity.

yeast bud that fails to detach itself that then forms a short chain of cells. candida albicans attaches to human epithelial cells as yeast

Discuss the sexual reproduction in fungi (three phases).

• Plasmogamy: haploid donor cell nucleus + penetrates cytoplasm of recipient cell − • Karyogamy: + and − nuclei fuse • Meiosis: diploid nucleus produces haploid nuclei (sexual spores)