Chapter 12- Eukaryotes (EXAM 2) Flashcards by Amreen Patel

Almost all molds are ________; most yeast are __________ __________; bacteria vary

aerobic; facultative anaerobes

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Most fungi can tolerate lower _____s and higher _________ _________ (i.e. higher sugar and salt concentrations) than bacteria

pHs; osmotic pressure

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________ require less moisture and nitrogen for growth than ________

fungi; bacteria

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Fungi can metabolize complex ____________ for energy (i.e. ________, a component of wood) that most bacteria cannot use

carbohydrates; lignin

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mycology

the study of fungi

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What are some harmful effects of fungi? (2)

Medically, fungal infections increasing over last 10 yrs due to health care
related infections and more people with compromised immune systems
Commercially, cause an estimated $1 billion dollars in damages to crops
annually

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What are some beneficial effects of fungi? (3)

• Critical for maintenance of the food chain/replenishment of soil nutrients
via decomposition of dead plant material, especially those parts animals can’t break down
• nearly all plants depend on symbiotic fungi
(Mycorrhizae) which aid roots in absorbing
nutrients from the soil
• used by humans as food (mushrooms), and to produce food (bread and citric acid) and drugs (alcohol and penicillin)

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what nutritional type are fungi?

chemoheterotrophs

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are fungi multicellular?

yes, except for yeast

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how do fungi acquire food?

absorption

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how do fungi reproduce?

sexual and asexual spores

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how are most fungi identified?

biochemical tests are used for yeast
However, multicellular fungi are identified on the basis of physical appearance: including colony characteristics and reproductive spores

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The fungal _______ (body) consists of

filamentous structures called _______

thallus; hyphae

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multinucleated, long, continuous cells

Coenocytic Hyphae

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uninucleated ,cell like units created by the formation of septa with a pore in the center

Septate Hyphae

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portion that anchors and absorbs nutrients

vegetative hyphae

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portion of the hyphae concerned with growth; projects above the surface of the medium

Reproductive/ Aerial Hypha

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Under favorable conditions a fungus can
colonize a substrate and produce masses of
hyphae visible to the eye. What is this mass called?

A hyphal mass is referred to as a mycelium.

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Non-filamentous, unicellular fungi

Typically spherical or oval

yeast

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what are the two methods by which yeast divide by?

fission yeasts

2. budding yeasts

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divide symmetrically; eg Schizosaccharomyces pombe

fission yeast

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divide asymmetrically; eg Saccharomyces

cerevisiae

budding yeast

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Buds that fail to detach from the parent cell form structures known as ____________

pseudohyphae

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a human pathogen that requires the

formation of pseudohyphae to aid in its pathogenicity

Candida albicans

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One yeast cell can in time produce | approximately ____ daughter cells by budding

Why is it beneficial for yeast to undergo respiration or fermentation?

Yeast can use O2 or an organic compound as final e acceptor (respiration or fermentation) - This allows them to inhabit more environments

For yeasts, which is preferred: aerobic or anaerobic respiration?

aerobic

in absence of ______, yeast can ferment carbohydrates to yield ______ and ______

O2; EtOH; CO2

describes the phenomenon whereby the yeast S. cerevisiae, produces EtOH aerobically in the presence of high external glucose concentrations

Crabtree Effect

What are some commercial uses of S. cerevisiae

- alcoholic beverage production | - leavening agent for bread production

What are fungi that grow either as a mold, forming hyphae, or as a yeast through budding called?

dimorphic fungi

Dimorphism in fungi can triggered by ___________ and _____ levels.

temperature; CO2

Dimorphism in ________ fungi is predominately temperature dependent, yeast-like at _____C and mold-like at ____C

pathogenic; 37; 25 | yeast pathogens are more dangerous to humans because they thrive at physiologic temperatures

filamentous fungi can reproduce asexually by | ____________ of their hyphae

fragmentation

unlike bacterial endospores, fungi are true __________ spores. Detaches from parent and germinates into _____ ______

reproduction; new mold

Which type of spore is genetically identical to the parent; and originate from a single hyphae?

asexual spores

Which type of spores arise from the fusion of nuclei from two opposite mating strains of the same fungal species?

sexual spores

Fungi that reproduce both sexually and asexually

telomorphs

Fungi that reproduce only asexually

anamorphs

a spore not enclosed in a sac

Conidiospore/conidium

Conidia is produced in a chain at the end of a _____________

conidiophore

easily dispersed asexual spore

conida = dust

which type of asexual spore is formed within a sac at the end of an aerial hypha?

sporangiospores

one ____________ can contain hundreds of ______________.

sporagium; sporangiospores

what are the two types of asexual spores?

conidiospore/ sporagniospore

types of conidia

Arthroconidia Blastoconidia Chlamydoconidia

spore released by fragmentation of a septate hypha, Slightly thicker than the hypha it was produced

Arthroconidia

budding from a parent cel

Blastoconidia

thick-walled spore formed by rounding and enlargement within hyphae

Chlamydoconidia

what are the three phases of sexual reproduction in spores?

Plasmogamy Karyogamy Meiosis

union of two haploid cells with mixing of the cytoplasm

Plasmogamy

sexual reporduction phase where + and – nuclei fuse

Karyogamy

Diploid nucleus produces haploid nuclei (sexual spores), some of which may be genetic recombinants

meiosis

The sexual spores produced by fungi determine the _______

phyla

However, many fungi reproduce only __________, and cannot be easily placed in a classification based on _________ characters.

asexually; sexual

Historically, fungi whose sexual cycle had not been observed were put in a “holding category” called ____________.

deuteromycota

Medically Important Phyla of Fungi

Zygomycota Ascomycota Basidiomycota Deuteromycetes/Fungi Imperfect

Most are Ascomycota that have lost ability to produce | sexually ( a few are Basidiomycetes) also are classified by rRNA

Deuteromycetes/ Fungi Imperfecti

a large diploid spore enclosed in a thick wall

Zygospore

sexually reproduced spores that are medically important

Zygospore Ascospore Basidiospore

What is the sexual spore that has a multi-nucleated diploid reproductive stage resulting from the fusion of the haploid nuclei from two cells

Zygospore

spores produced in saclike structure called an _______ - results from the fusion of the nuclei from two cells. ________ spores are produced during meiosis. What type of sexual spore is this?

ascus; haploid; Ascospore

What is the sexual spore that has haploid spores formed externally on a __________.

pedestal (basidium); | Basidiospore

Any fungal disease

mycosis

Mycoses are generally _________ infections | because fungi grow slowly

chronic (long-lasting)

since fungi and animals are both ________, drugs that affect fungal cells may also affect animal cells. Thus, fungal infections in animals and humans are often hard to treat

eukaryotic

Mycoses are classified into _____ groups according to the degree of tissue involvement and mode of entry into the host

five

Degrees of Mycoses (5)

``` Superficial Cutaneous or Dermatomycoses Subcutaneous Systematic Opportunistic ```

limited to the outermost layers of the skin and hair. Infections prevalent in tropical climates.

superficial

infect only the nails, skin and hair. These fungi are called ___________. Transmission occurs from either human or animal to human by ___________ or contact with __________ etc)

dermatophytes; direct contact; infected hairs; | description of cutaneous or dermatomycoses

beneath the skin; caused by fungi that live in _____ or on __________. Infection occurs by direct spore implantation into a puncture wound

soil; vegetation; subcutaneous

can affect a number of organs and tissues. Usually caused by _____ fungi. Inhalation of spores is the route of transmission; infections usually spread from lungs to other parts of the body.

soil; systematic

usually harmless but become pathogenic in an immunocompromised host

opportunistic

called conjugation fungi, sporangium fungi or common mold

Phyla Zygomycota

Molds that have coenocytic hyphae

Phyla Zygomycota

Asexual spore type in phyla zygomycota

sporangiospores

how do zygomycota reproduce sexually?

reproduces sexually by means of zygospores

- called Sac fungi (due to the ________) • includes molds with septate hyphae and some yeast • Asexual spores: ___________ • Sexual spores: ___________

ascus; conidiospores; ascospores Phyla Ascomycota

* called club fungi derived from the club shape of the __________ * includes fungi that produce _______ * posses septate hyphae * Asexual spore type: some produce ___________ (others reproduce by ___________) * Sexual spore type: ___________

basidium; mushrooms; conidiospores; fragmentation; basidiospores (Basidiomycota)

``` Produce asexual spores only – rRNA sequencing places most in __________; a few are ___________ – Penicillium – Candida albicans-- _________ ________ ```

(Anamorphs) ascomycota; basidiomycota; cutaneous mycoses

used to produce citric acid (since 1914)

Aspergillus niger

used to produce bread, wine, beer, and genetically modified to produce a variety of proteins (i.e. HBV vaccine)

Saccharomyces cerevisiae

produces the enzyme Cellulase used to digest | plant cell walls to produce a clear fruit juice, etc.

Trichoderma

produces Taxol, an anticancer drug (1967- 1993 | the bark of Pacific yew trees was only source)

Taxomyces

kills gypsy moths

Entomophaga

grows on plant roots. Parasitic weevils that eat the roots die

Metarrhizium

foam containing fungi used to kill termites

Paecilomyces fumosoroseus

feeds on other fungi that feed on soybeans

Coniothyrium minitans

_______ (not bacteria) commonly spoil fruits, grains and vegetables - little moisture on the unbroken surface - fruit interiors are too ______ for many bacteria

molds; acidic

Molds spoil jams and jellies - tend to be acidic and have a high _______ due to sugars - a ________ layer will keep out oxygen and deter mold growth

osmolarity; parrafin

Fungi have devastated some tree species - A fungal blight caused by an __________ killed almost all spreading chestnut trees in the U.S. - The dutch elm disease has devastated the American elm population

ascomycete

which kingdom are lichens placed into?

fungi

Mutualistic relationship between a green alga (or ___________) and a fungus (usually an ___________) – Require the mutualistic relationship for each to exist – Exist where neither an alga or fungus could exist alone • typically first life forms to colonize newly exposed soil and rock • found on trees, concrete and rooftops

cyanobacteria; ascomycete

Alga produces and secretes ___________; fungus provides attachment (_________) and protection from __________ (cortex)

carbohydrates; rhizines; desiccation

______ secrete organic acids to chemically weather rock | • Some of the slowest growing organisms on Earth

lichens

what are the three morphological categories of lichens

Fruticose Foliose Crustose

lichens that have finger-like projections

fruticose

lichens that are leaf-like

foliose

lichens that are flat

crustose