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The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

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Presentation on theme: "The Eukaryotes: Fungi, Algae, Protozoa, and Helminths"— Presentation transcript:

1 The Eukaryotes: Fungi, Algae, Protozoa, and Helminths
12 The Eukaryotes: Fungi, Algae, Protozoa, and Helminths

2 Fungi Eukaryotic Cells contain a nucleus
Aerobic or facultatively anaerobic Makes ATP (energy) through respiration if oxygen is present, but can go through fermentation if oxygen is not present Chemoheterotrophic Must break down and absorb organic compounds for energy and carbon Most are decomposers

3 Types of fungi: Molds The thallus (body) of a mold consists of long filament of cells joined together called hyphae Grow by elongating at the tips Every part of a hypha (singular) is capable of growing Most fungus grown in labs is grown from fragments When conditions are favorable for growth, hyphae will grow into a mass called a mycelium Figure 12.2

4 Types of Hypha Vegetative hypha
The portion of a hypha that obtains nutrients Aerial hypha Portion of hypha concerned with reproduction Projects above the surface the mold is growing on Usually produce reproductive spores

5 Types of Fungi: Yeasts Nonfilamentous, unicellular fungi
Typically spherical or oval in shape Two types: Budding yeasts - divide unevenly A protuberance known as a bud forms on the surface of a parent cell and elongates, eventually breaking off after the nucleus divides Some yeast buds fails to detach and instead form a small chain of cells called a pseudohypha Ex: Candida albicans attaches to human skin cells but require pseudohypha to get to deeper tissue Figure 12.3


7 Fission yeasts Divide evenly to produce two new identical cells Entire parent cell elongates and splits Similar to bacterial fission

8 Dimorphism - The ability to take on two different forms
Can grow as either yeasts or molds Usually temperature dependent histoplasma capsulatum below is yeast like at 37 C (left), but mold like below 36 C (right) Can be dependent on presence or lack of CO2 Figure 12.4

9 Fungal life cycle Fungi reproduce both sexually and asexually through the use of spores Formed from aerial hyphae Asexual spores are formed by hyphae of one organism When they germinate, they produce genetically identical organisms to the parent

10 Types of asexual spores Conidiospore
Uni or multicellular spore that is not enclosed in a sac Sporangiospore – formed within a sac A single sac can contain hundreds of spores

11 Sexual spores result from fusion of the nuclei from two strands of the same species
Results in organisms with characteristics of both parental strands Three phases Plasmogamy: nuclues of donor cell penetrates cytoplasm of recipient cell Karyogamy: two nuclei fuse Meiosis: nucleus divides to form spores


13 The difference between bacteria and fungi
Fungi are adapted to environments that would be hostile to most bacteria Grow better in environments that are too acidic for bacterial growth Can grow in high sugar or salt concentrations Can grow on substances with low moisture content Require less nitrogen Can metabolize complex carbs

14 Fungi Phyla The following three phyla are telemorphs
Can reproduce both sexually and asexually Zygomycota Conjugation fungi Reproduction occurs when hypha of two fungi merge together to form spores instead of using a reproductive structure such as a mushroom cap Have coenocytic hyphae Multinuclear Occurs when there is mitosis but not cytokinesis

15 Zygomycete Life Cycle Zygospores are created when two fungal hypha
fuse – sexual reproduction A sporangium will form from the zygospore which produces hundreds of identical spores to be released for new fungi to grow – asexual repro. Figure 12.6

16 Ascomycota Sac fungi Septated hyphae The hypha have a cell wall-like septa within to make it look like it is multicellular Some are anamorphs – have lost the ability to reproduce sexually

17 Ascomycete Life Cycle Asexual repro: spores are usually conidia that are produced in long chains and can freely detach Sexual repro: ascopores result from the fusion of two nuclei Produced in the ascus (saclike structure) Figure 12.7

18 Basidiomycota Club fungi Septate hyphae Include fungi that produces mushrooms

19 Basidiomycete Life Cycle
Asexual repro: portion of hypha breaks off and grows into a new hypha/mycelium Sexual repro: basidiospores are produced on the basidium In cap mushrooms, these are located on the gills Figure 12.8


21 Fungal diseases Mycosis: any fungal infection
Generally chronic (long-lasting) because of the slow growth of fungi Classified into 5 groups Based on the degree of tissue involvement and mode of entry into host Many are difficult to treat because of the close evolutionary relationship between fungal and animal cells

22 Systemic mycoses Fungal infections deep within the body
Can affect a number of tissues and organs Not restricted to any one region of the body Usually caused by fungi found in soil Transmitted through inhalation of spores Typically begin in the lungs and spread to other tissue Not contagious Ex: histoplasmosis(aka cave disease)

23 Disseminated histoplasmosis: has spread beyond the lungs and is life threatening at this point

24 Subcutaneous mycoses Fungal infections beneath the skin
Caused by saprophytic fungi (decomposers – break down dead/decaying matter) that live in soil and on vegetation Ex: sporotrichosis Common in gardeners and farmers that causes lesions on the hands (or wherever comes in contact) Infection occurs when spores or part of the mycelium enter a puncture wound on skin

25 Cutaneous mycoses Aka dermatomycoses
Infect the epidermis, hair and nails Caused by dermatophytes Secrete keratinase, an enzyme that breaks down keratin Transmitted human to human or animal to human by direct contact with infected hair or epidermal cells Ex: athlete’s foot and ringworm


27 Superficial mycoses Infections localized along hair shafts and in surface epidermal cells Most prevalent in tropical climates Very similar to cutaneous Difference is the localization – does not spread around the body

28 Opportunistic mycoses
Caused by normal microbes or fungi that typically are harmless Become pathogenic in a host with a compromised immune system Examples: Pneumocystis - most common life-threatening infection in AIDS patients Stachybotrys – normally grows on cellulose of dead plants, can cause fatal pulmonary hemorrhage in infants when found in homes

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