CH.12 MICROBIOLOGY OUTLINE

–>Eukaryotic microbes include a fascinating and almost bewilderingly diverse assemblage. – includes unicellular and multicellular protozoa, fungi, algae, water molds, and slime molds. – ex; marine algae called diatoms and a set of protozoa called dinoflagellates provide ocean food chains. – eukaryotic fungi produce penicillin, and yeasts for making bread and alcoholic beverages.

–> Among the 20 most frequent microbial causes of death world-wide, six are eukaryotic, including the agent of malaria, African sleeping sickness, and amebic dysentery. – Pneumocytis pneumonia, toxoplasmosis, and cryptosporidiosis which are common afflictions of AIDS patients.–> A unique characteristic of living things is the ability to reproduce themselves. – Prokaryotic reproduction typically involves replication of DNA and binary fission of the cytoplasm to produce two identical offspring.
–> Most of the DNA in eukaryotes is packed with histone proteins as chromosomes in the form of chromatin fibers located within nuclei. – DNA are found in the mitochondria and chloroplasts
–> eukaryotes have a variety of methods of asexual reproduction, including binary fission, budding, fragmentation, spore formation, and schizogony.
–> Many eukaryotes

–> typicically, a eukaryotic nucleus has either one or two complete copies of the chromosomal portion of a cell’s genome. – A nucleus with a single copy of each chromosome is called a “haploid”, or 1n, nucleus, and one with 2 sets of chromosomes is “diploid”, or 2n, nucleus.
–> The cells of most fungi, many algae, and some protozoa are haploid, and the cells of most plants and animals and the remaining fungi, algae, and protozoa are diploid.
–> A cell divides its nucleus so as to pass a copy of its chromosomal DNA to each of its descendants so that each new generation has the necessary genetic instructions to carry on life. – two types: “mitosis” and “meiosis”.

–> eukaryotic cells have 2 main stages in their life cycle: a stage called “interphase”, during which the cells grow and eventually replicate their DNA, and a stage during which the cell’s nucleus divides. – In the type of nuclear division called “mitosis”, which begins after the cell has duplicated its DNA such that there are 2 exact DNA copies.
–> Mitosis has four phases: prophase, metaphase, anaphase, and telophase.

–> the cell condenses its DNA molecules into visible threads called “chromatids”. – “chromatids”, sister DNA molecules, are joined together in a region called a “centromere” to form one chromosome. – microtubules are constructed in the cytosol for form a “spindle”.

–> the chromosomes line up on a plane in the middle of the cell and attach near their centromeres to microtubules of the spindle.

–> sister chromatids separate and crawl along the microtubules toward opposite poles of the spindle. – where each chromatid is called a chromosome.

–> the cell restores its chromosomes to their less compact, nonmitotic state, and nuclear envelopes form around the daughter nuclei.

–> Students sometimes….during prophase and metaphase, a chromosome consists of 2 chromatids (DNA molecules) joined at a centromere. – …anaphase and telophase, the chromatids separate, and each chromatids is then called a chromosome.

–> In contrast to mitosis, “meiosis” is nuclear division that involves the partitioning of chromatids into four nuclei such that each nucleus receives only half the original amount of DNA.
–> Meiosis occurs in 2 stages known as “meiosis I” and “meiosis II”

–> aka (prophase of meiosis I), as with mitosis, DNA replication during interphase has resulted in pairs of identical chromatids, forming chromosomes. – “homologous chromosomes” are identical genetic sequences that line up side by side. – an aligned pair of homologous chromosomes is known as a “tetrad.

–> once tetrads have formed, the homologous chromosomes exchange secretions of DN in a random fashion via a process called “crossing over”.

–> tetrads align on a plane in the center of the cell and attach to spindle microtubules.

–> chromosomes of the tetrads move apart from one another; however, in contrast to mitotic anaphase, sister chromatids remain attached to one another.

–> the first stage of meiosis is completed as the spindle disintegrates. – nuclear envelopes may form. – each haploid chromosome consists of 2 chromatids.

–> nuclear envelopes disintegrate, and new spindles form.

–> the chromosomes align in the middle of each cell and attach to microtubules of the spindles.

–> sister chromatids separate as in mitosis.

–> daughter nuclei form. – cells divide yielding 4 haploid cells.

–> in summary, meiosis produces 4 haploid nuclei from a single diploid nucleus.

–> CYTOPLASMIC DIVISION AKA “CYTOKINESIS”, typically occurs simultaneously with telophase of mitosis, though in some algae and fungi it may be postponed or may not occur. – in mitosis, multinucleate cells called “coenocytes”.
–> In plant and algal cells, cytokinesis occurs as a vesicles deposit wall material at the equatorial plane between nuclei to form a cell plats, which eventually become a transverse wall between daughter cells.

–> Some protozoa, such as “Plasmodium”-the cause of malaria reproduce asexually within red blood cells and liver cells via a special type of reproduction called “schizogony”. – in schizogony, multiple mitoses form a multinucleate “schizont”; which cytokinesis occur, simultaneously releasing numerous uninucleate daughter cells called “merozoites”.

–> historically, the classification of many eukaryotic microbes has been fraught with difficulty and characterized by change. – since the late 18th century, when Carolus Linnaeus (1707-1778) began modern taxonomy, until near the end of the 20th century, taxonomists grouped organisms together largely according to readily observable structural traits. – unicellular algae and fungi are plants. – protozoa are animals. – by late 20th century he place protozoa and algae in kingdom Protista.
–> This scheme was trouble some, in part because the protista included both large, photosynthetic, multicellular kelps and nonphotosynthetic unicellular protozoa.
–> More recently, many taxonomists have abandoned classification schemes that are strongly grounded in large-scale structural similarities in favor of schemes based on similarities in nucleotide sequences and cellular ultrastructure as revealed by electron microscopy.

–> mitosis: during interphase, before nuclear division.
–> meiosis: during interphase, before meiosis I begins

–> mitosis: prophase, metaphase, anaphase, telophase.
–> meiosis: meiosis I > prophase I, metaphase I, anaphase I, telophase I.
meiosis > prophase II, metaphase II, anaphase II, telophase II

–> mitosis: does not occur
–> meiosis: early in prophase I

–> mitosis: does not occur
–> meiosis: following formation of tetrads during prophase I

–> mitosis: one
–> meiosis: two

–> mitosis: two nuclei with same ploidy as the original
–> meiosis: four nuclei with half the ploidy of the original

–> The microorganisms called “protozoa” are a diverse group defined by 3 characteristics: they are eukaryotic, are unicellular, and lack a cell wall. – except apicomplexans, protozoa are mobile by cilia, flagella, and pseudopodia.
–> Most of them are chemoheterotrophs.

–> Protozoa require moist environments; most species live worldwide in ponds, streams, lakes, and oceans, where they are critical members of the plankton, free-living, drifting organisms that form the basis of aquatic food chains.

–> Though protozoa have most of the features of eukaryotic cells, this group of eukaryotic microbes is characterized by great morphological diversity.
–> Some ciliates have 2 nuclei: a larger “macronucleus”, which contains many copies of the genome (often more than 50n) and controls metabolism, growth, and sexual reproduction, and a smaller “micronucleus, which is involved in genetic recombination, sexual reproduction, and regeneration of macronuclei.
–> Protozoa also show variety in the number and kind of mitochondria they contain. – “contractile vacuoles” > actively pumps water from the cells, protecting them from osmotic lysis.
–> All free-living aquatic and pathogenic protozoa exist as a motile feeding stage called a “trophozoite”, and many have a hardy resting stage called a “cyst”, which is characterized by a thick capsule and a low metabolic rate.

–> Defined by 3 characteristics: eukaryotic, unicellular, and lack a cell wall. – they are motile by means of cilia, flagella, and pseudopodia.

–> In which all free-living aquatic and pathogenic protozoa exist as a motile feeding stage.

–> Characterized by a thick capsule and a low metabolic rate. – protozoa cysts are not reproductive structures because one trophozoite forms one cysts that later becomes one trophozoite. – cysts allows survival of harsh environmental conditions such as desiccation, nutrient deficiency, extremes of pH and temperature, and lack of oxygen.

–> Most protozoa are chemoheterotrophic; that is, they obtain nutrients by phagocytizing bacteria, decayed organic matter, other protozoa, or the tissues of a host; a few protozoa absorb nutrients from the surrounding water. – dinoflagellates and euglenids are are photoautotrophic.

–> Most protozoa reproduce asexually only, by binary fission or schizogony; a few protozoa also have sexual reproduction in which 2 individuals exchange genetic material. – some sexually reproducing protozoa become “gametocytes” that fuse with one another to form a diploid “zygote”

–> in which some sexually reproducing protozoa’s become.

–> gametes that fuse with one another to form a diploid.

–> As we have seen, over two centuries ago Linnaeus classified protozoa as animals; later taxonomists grouped protozoa into kingdom Protista. – protozoa has four groups: sarcodina (motile by means of pseudopods), Mastigophora (flagella), ciliophora (cilia), and sporozoa (nonmotile).
–> Taxonomists today recognize that these schemes do not reflect genetic relationships either between protozoa and other organisms or among protozoa.
–> we will discuss 6 taxa protozoa: parabasala, diplomonadida, euglenozoa, euglenids, kinetoplastids, alveolates, ciliates, apicomplexans, dinoflagellates, rhizaria, amoebozoa, plasmodial (acellular) slime molds plasmodial slime molds, cellular slime molds.

–> These lack mitochondria; they have a single nucleus and “parabasal body”, which is a golgi body-like structure. – “trichonympha”, a parabasalid with numerous flagella, inhabits the guts of termites, where it assists in the digestion of wood. – ex; “trichomonas” which lives in the human vagina. – they cause inflammation when pH in vagina raises.

–> Because members of the group Diplomonadida lack mitochondria, golgi bodies, and peroxisomes, biologists once thought. – discovered “mitosomes” in the cytoplasm and mitochondrial genes in the nuclear chromosomes, suggesting that diplomonads might be descended from typical eukaryotes that somehow lost their organelles.
–> Diplomonads have 2 equal-sized nuclei and multiple flagella. – Ex; “Giardia”, a diarrhea causing pathogen of animals and humans that is spread to new hosts when they ingest resistant “Giardia” cysts.

–> part of the reason that taxonomists established the kingdom Protista in the 1960s was to create a dumping ground for euglenids, eukaryotic microbes that share certain characteristics of both plants and animals. – the presence of a crystalline rod of unknown function in the flagella, and the presence of mitochondria with disk-shaped cristae, some taxonomists have created a new taxon: Kingdom Euglenozoa. – euglenozoa include euglenids and some flagellated protozoa called “kinetoplastids”.

–> The group of euglenozoa called “euglenids”, which are named for the genus Euglena, are photoautotrophic, unicellular microbes with chloroplasts containing light-absorbing pigments, chlorophylls a and b and carotene. – they store food as a unique polysaccharide called “paramylon” instead of as starch. – similar to animals in that they >lack cell walls<, have >flagella<, and has a flowing, contracting, expanding cytoplasm. - they have a squirming movement like amoeboid but not like pseudopods, which is called "euglenoid movement". --> A euglenid has a flexible, proteinaceous, helical “pellicle” that underlies its cytoplasmic membrane and helps maintain its shape. – they have a a red “eyespot” for positive phototaxis by casting a shadow on a photoreceptor at the flagellar base. – they have cyts. – they produce by mitosis followed by longitudinal cytokinesis.

–> euglenozoa called “kinetoplastids each have a single large mitochondrion that contains a unique region of mitochondrial DNA called a “kinetoplast”.
–> Kinetooplastids live inside animals, and some are pathogenic. – Ex; “Trypanosoma” and “Leishmania”

–> “Alveolates” are protozoa with small membrane bound cavities called alveoli beneath their cell surfaces. – they have tubular mitochondrial cristae. – this group is further divided into three subgroups: “ciliates”, “apicomplexans”, and “dinoflagellates”.

–> as their name indicates, “ciliate” alveolates have cilia by which they either move themselves or move water past their cell surfaces. – all ciliates are chemoheterotrophs and have 2 nuclei, one macronucleus and one micronucleus.
–> Notable ciliates include “Vorticella”, whose apical cilia create a whirlpool like current to direct food into its “mouth”; “Balantidium”, which is the only ciliate pathogenic to humans; and the carnivorous “Didnium”, which phagocytizes protozoa, like the pond-water ciliate “Paramecium”.

–> the alveolates called “apicomplexans” are all chemoheterotrophic pathogens of animals. – they have “complex” special intracellular organelles located at the “apices” of the infective stages of these microbes. Ex; “plasmodium”, “Cryptosporidium”, and “Toxoplasma”, which causes malaria, cryptosporidiosis, and toxoplasmosis.

–> The group of alveolates called “dinoflagelates” are unicellular microbes that have photosynthetic pigments, such as carotene and chlorophylls a, c1, and c2. – food reserves includes starch and oil, and their cells are strengthened by internal plates of cellulose. – their 18S rRNA sequences and the presence of alveoli indicate that dinoflagellates are more closely related to ciliates and apicomplexans than they are to either plants or algae. – unlike other eukaryotic chromosomes, dinoflagellate chromosomes lack histone proteins.
–> Dinoflagellates make up a large proportion of freshwater and marine plankton. – the motile ones have 2 flagella of unequal length.
–>Many dinoflagellates are bioluminescent, that is, able to produce light via metabolic reactions. – others produce a red pigment, and their abundance in marine water is one cause of a phenomenon called a “red tide”.
–> Some dinoflagellates, such as “gymnodinium” and “gonyaulax”, produce “neurotoxins” poisons that can act against the human nervous system.
–> The neurotoxin of another dinoflagellate, “Pfiesteria”, may be even more potent: It has been claimed that the toxin poisons people who merely handle infected fish or breathe air laden with the microbes, resulting in memory loss, confusion, HA, respiratory difficulties, skin rash, muscle cramps, diarrhea, nausea, and vomiting. – CDC calls the poisoning “possible estuary-associated syndrome (PEAS).

–> a red pigment and their abundance in marine water is one cause of a phenomenon.

–> unicellular eukaryotes called “amoebae” are protozoa that move and feed by means of pseudopods. Some taxonomists currently classify amoebae into 2 kingdoms: Rhizoaria and Amoebozoa.
–> Rhizaria is a group of amoebae with threadlike pseudopods. – A major taxon is composed of armored marine amoebae known as “foraminifera”, which has a porous shell composed of calcium carbonate arranged on an organic matrix in a snail like manner. – they live in sand grains on ocean floors.
–> over 90% of known foraminifera are fossil species, some of which form layers of limestone hundreds of meters thick.
–> Amoebae called “radiolaria” make up another group of rhizaria, but they have ornate shells composed of silica (SiOx, the mineral found in opal) and live unattached as part of the marine plankton.

–> unicellular eukaryotes that are protozoa which moves and feeds by means of pseudopods.

–> in the rhizaria group of amoebae with threadlike pseudopods that has a porous shell composed of calcium carbonate arranged on an organic matrix in a snail like manner.

–> Amoebozoa constitute a second kingdom of amoebae distinguished from rhizaria by having lobe-shaped pseudopods and noshells. – Ex; “naegleria” & “acanthamoeba”, which causes diseases of the eyes or brains of humans and animals that swim in water containing them. – Ex; “Entamoeba”, live inside animals, where they produce potentially fatal amebic dysentery.
–> Taxonomists formerly considered another group of amoebozoa “slime molds”, to be fungi, but the lobe shaped pseudopods by which they feed and move as well as their nucleotide sequences show that they are amoebozoa. – two are identified: “plasmodial molds and “cellular slime molds”.
–> Species in the 2 groups of slime molds differ based on their morphology, reproduction, and 18S rRNA sequences.

–> amoebozoa classification of protozoa in which they lack cell walls, and that they are phagocytic rather than absorptive in their nutrition.

–> aka known as “acellular slime mold”, exist as streaming, coenocytic, colorful filaments of cytoplasm that creep as amoebae through forest litter, feeding by phagocytizing organic debris and bacteria.
– nutrients are distributed throughout the plasmodium by cytoplasmic streaming.
–> When food or water is in short supply, the plasmodium divides into individual masses of > cytoplasm, each of which produces a stalked sporangium. – Spores germinate to produce “myxamoebae, which look and act like other unicellular amoebae in the presence of water,
–> Compatible myxamoebae of opposite mating types fuse to form a diploid zygote.

–> such as “Dictyostelium” exist as individual haploid myxamoebae that phagocytize bacteria, yeasts, dung, and decaying vegetation. – produce by mitosis and cytokinesis when food is abundant, some secrete cyclic adenosine monophosphate (cAMP), which acts as a chemotactic attractant for other myxamoebae.
–> Some cells of a pseudoplasmodium form a stalked sporangium; the remaining cells climb the stalk and become spores.

–> Myxamoebae fuse to form a coenocytic plasmodium that feeds on organic debris and bacteria as plasmodium creeps. – it produces sporangia undergoes meiosis producing haploid spores. – spores fuse to form zygote undergoing multiple mitosis, but no cytokinesis to form new plasmodium.

–> myxamoebae congregate during times of starvation to form a multicellular slug, producing stalked sporagium – myxamoebae retain their individuality. – sporangium releases spores that germinate when conditions are more favorable. – all phases are haploid.

–> in which fungi produces diseases of plants, animals, and humans. – Ex; Dutch elm disease and athlete’s foot.

–> parabasal body; single nucleus; lack mitochondria.
–> Trichomonas

–> 2 equal-sized nuclei; lack mitochondria, golgi bodies, and peroxisomes.

–> multiple flagella
–> Giardia

–> flagella with internal crystalline rod; disk shaped mitochondrial cristae

–> photosynthesis; pellicle, “eyespot”
–> Euglena

–> single mitochondrion with DNA localized in kinetoplast
–> Trypanosoma, Leishmania

–> Alveoli (membrane-bound cavities underlying the cytoplasmic membrane); tubular cristae in mitochondria

–>ceilia
–> Balantidium, Paramecium, Didnium

–>apical complex of organelles
–> Plasmodium, Cryptosporidium, Toxoplasma

–> photosynthesis; 2 flagella; internal cellulose plates
–> Gymnodinium, Gonyaulax, Pfiesteria

–> threadlike pseudopods

–> shells of calcium carbonate

–> threadlike pseudopods, shells of silica

–> lobe shaped pseudopods; no shells

–> do not form aggregates
–> Naegleria, Acanthamoeba, Entamoeba

–> multinucleate body called plasmodium
–>Physarum

–> cells aggregate to form pseudoplasmodium but retain individual nature
–> Dictyostelium

–> Organisms in the kingdom “Fungi”, such as molds, mushrooms, and easts, are like most protozoa in that they are chemoheterotrophic; unlike protozoa, they have cell walls, which are typically composed of strong, flexible, nitrogenous polysaccharide called “chitin”, which is similar exoskeletons of insects and other arthropods, such as grasshoppers, lobsters, and crabs. – The study of fungi is “mycology” and scientists, “mycologists”.

–> Fungi are extremely beneficial microorganisms. – they decompose dead organisms (particularly plants) and recycle their nutrients. – roots of about 90% of vascular plants form “mycorrhizae” associated between roots and fungi that assist the plants to absorb water and dissolved minerals.
–> Human use fungi for food (mushrooms and truffles), in religious ceremonies, and in the manufacture of foods and beverages, including bread, alcoholic beverages, citric acid. – fungi produces antibiotics like penicillin and cephalosporin; also “cyclosporine”, and immunosuppressive drug for transplants; and “mevinic acids”, a cholesterol reducting agent.
–> Fungi are also important research tools in study of metabolism, growth, and development in genetics and biotechnology.
–> Not all fungi are beneficial, about 30% of known fungal species produce “mycoses” , which are fungal diseases of pants, animals, and humans. – Ex; Dutch elm disease is a mycosis of elm trees, as well as athlete’s foot. – they tolerate salt, acid, and sugar that inhibit bacteria, therefor they cause spoilage of fruit, pickles, jams, and jellies.

–> fungi have two basic body shapes: bodies of “molds” are relatively large, composed of long, branched, tubular filaments called “hyphae”. – Hyphae are either “septate” (divided into cells by cross walls called “septa”, or “aseptate” (not divided by septa. – aseptate hyphae are “coenocytic” which are (multinucleate). – “yeasts” are typically small, blobular, composed of single cell, that have buds.
–> In response to environmental conditions such as temperature or carbon dioxide concentration, some fungi produce both yeastlike and moldlike shapes; fungi that produce 2 types of body shapes said to be “dimorphic” (which means two shaped), in that they change growth habits in response to temp. – Ex; “Histoplasma capsulatum”, causes a respiratory disease called histoplasmosis, “Coccidioides immitis”, which causes flulike disease called coccidioidomycosis.- dimorphic yeast form causes diseases and the filamentous kind does not.
–> The body of a mold is composed of hyphae intertwined to form a tangled mass called a “mycelium”. – the largest known organisms on Earth are fungi in genus “Armillaria”, that can spread through thousands of acres of forest to a depth of several feet and weigh hundred of tons. – “fruiting bodies” like puffballs and mushrooms are hyphae of reproductive structures of molds.

–> In which fungi have bodies of molds relatively large and composed of long, branched, tubular filaments.

–> in which fungi are divided into cells by cross walls called septa.

–> in which fungi/mold are not divided by cross walls.

–> in which the fungi/mold is composed of hyphae intertwined to form a tangled mass.

–> fungi acquire nutrients by absorption; that is, they secrete catabolic enzymes outside their bodies to break large organic molecule into smaller molecules, which they then transport throughout their bodies. – “saprobes” are what most fungi which they absorb nutrients from the remnants of dead organisms. – “Haustoria” are fungi that derive their nutrients from living plants and animals usually have modified hyphae.
–> recently, scientists have discovered that some fungi use ionizing radiation (radioactivity) as an energy source for metabolism.
–> Most fungi are aerobic, though many yeasts are facultative anaerobes that obtain energy from fermentation, such as occurs in the reactions that produce alcohol. – anaerobic fungi are found in digestive systems of herbivores, cattle, deer, in they catabolize plant material.

–> what most fungi are in they absorb nutrients from the remnants of dead organisms.

–> Fungi that derive their nutrients from living plants and animals usually having modified hyphae.

–> whereas all fungi have some means of asexual reproduction involving mitosis followed by cytokinesis, most fungi also reproduce sexually.

–> yeasts typically bud in a manner similar to prokaryotic budding. – Ex; “Candida albicans” causes oral thrush and vaginal yeast infections. – “pseudohypha” is a long filament that forms. – “candida” invades human tissues by means of pseudohyphae that penetrates intercellular cracks.
–> Filamentous fungi reproduce asexually by producing lightweight spores, which enable the fungi to disperse vast distances on the wind.
– Asexual spores includes: “Sporangiospores” that form inside a sac called a “sporangium” often borne on a spore-bearing stalk, called a “sporangiophore” at either tips or sides of hyphae.
–>”Chlamydospores” form with a thickened cell wall inside hyphae.
–> “Conidiospores” are produced at the tips or sides of hyphae but not within a sac and also develop in chains on stalks called “conidiophores”.

–> Scientists designate fungal mating types as “+” and “-” rather than as male and female, in part because their bodies are morphologically indistinguishable in which fungi has 4 basic steps:
–> 1) haploid cells from a (+) fungus and a (-) fungus fuse to form a “dikaryon”, a cell containing both + and nuclei. – its neither diploid nor hapoid but instead designated (n+n).
2) after a period of time that typically ranges from hours to years but can be centuries, a pair of nuclei within a dikaryon fuse to form one diploid (2n) nucleus.
3) Meiosis of the diploid nucleus restores the haploid state.
4) The haploid nuclei are partitioned into (+) and (-) spores, which reestablish (+) and (-) fungi by mitoses and cell divisions.

–> they consider the four major subgroups into which taxonomists traditionally divided the kingdom fungi. – sexual spore produced divisions of Zygomycota, Ascomycota, and Basidiomycota, and the fourth, the (Deuteromycetes) that has no sexual stage.

–> Fungi in the division “Zygomycota” are coenocytic molds called zygomycetes. – most are saprobes, the rest are obligate parasites of insects and fungi.
–> Ex; the black bread mold “Rhozopus nigricans”; a distinctive feature of most zygomycetes is the formation of sexual structures called “zygosporangia”. – “R. nigricans” are black, rough walled structures that develop from the fusion of sexually compatible hyphal tips. – like fungal spores, zygosporangia can withstand desiccation and other harsh environmental conditions.
–> within a zygosporangium nuclei from one hypha (+) fuse with nuclei from the other hypha (-) to form many diploid nuclei.

–> are small organisms that are difficult to classify.
–> They are obligatory intracellular parasites; that is organisms that must live within their hosts cells. – Ex; “nosema”, which is parasitic on insects, such as silkworms and honeybees and also a biological control agent for grasshoppers. – “Nosema, Encephalatizoon, and Microsporidium” are known to cause diseases in immunocompromised patients.

–> The division “Ascomycota” contains about 32,000 known species of molds and yeasts that are characterized by the formaton of haploid “acospores” within sacs called “asci” that occur in fruiting bodies called “ascocarps”. – Ascomycota reproduce asexually by conidiospores.
–> Ascomycetes are familiar and economically important fungi. – “Claviceps purpurea” growing on grain produces “lysergic acid”, which causes abortions in cattle and hallucinations in humans. “Aspergillus” can also infect humans.
–> On the other hand, many asocmycetes are beneficial. – Ex; “penicillium” mold is the source of penicillin; “Saccharomyces”, which ferments sugar to produce alcohol and carbon dioxide gas; “truflles” grow as mycorrhizae in associatio with oak and beech trees to form culinary delights. – Ex; “Neurospora” is the pink bread mold. – Ex; “lichens” what forms green algae or cyanobacteria

–> 1) hypha produces conidiophores and conidiophores and conidiospores
–> 2) conidiospores are released
–> 3) conidiospre germinates producing mycelium
–> 4) vegetative mycelium grows
–> 11) Ascospore herminate to produce mycelia.

–> 5) hyphal tip undergoes cytoplasmic fusion with opposite mating type.
–> 6) Dikaryon (n+n) forms
–> 7) nuclei fuse in terminal cells to form 2n nuclei.
–> 8) Meiosis produces four haploid (1n) cells.
–> 9) Mitosis produces eight haploid ascospores on each tip.
–> 10) Ascus opens to releas ascospores.
–> 11) ascospores germinate to produce mycelia.

–> A walk through fields and woods in most parts of the world may reveal mushrooms, puffballs, stinkhorns, jelly fungi, bird’s nest fungi, or bracket fungi, all of which are the visible fruiting bodies of the almost 22,000 known species of fungi in the division “Basidiomycota”.
–> Mushrooms and other fruiting bodies of “basidiomycetes” are called “basidiocarps”. – “Amanita muscaria” is a poisonous mushroom (toadstool).
–> Besides the edible mushrooms, most notably, cultivated “Agaricus”, basidiomycetes affect humans in several ways. – they’re important decomposers of cellulose and lignin in dead plants and return nutrients to soil. – “Psilocybe cubensis” is a mushroom that produces toxins or hallucinatory chemicals. – “Crytococcus neoformans” is the leading cause of fungal meningitis.

–> As noted previously, the division Zygomycota, Ascomycota, and Basidiomycota are based on type of sexual spore produced. – an “imperfect fungi” to contain the fungi whose sexual stages are unknown. – the analysis of rRNA sequences has revealed that most deuteromycetes in fact belong in the division Ascomycota.

–> A discussion of fungi is incomplete without considering “lichens” which are partnerships between fungi and photosynthetic microbes commonly cyanobacteria or less frequently, green algae. – the hyphae of the fungus, usually an ascomycete, surround the photosynthetic cells and provide then nutrients, water, and protection from desiccation and harsh light.
–> The partnership in a lichen is not always mutually beneficial, in some lichens, the fungus produces haustoria that penetrate and kill the photosynthetic member.
–> The fungus of a lichen reproduces by spores, which must germinate and develop into hyphae that capture an appropriate cyanobacterium or alga. – “soredia”, in which wind, rain, and small animals disperse bits of lichen, which contain both phototrophs and fungal hyphae
–> Scientists have identified over 14,000 species of lichens, which are abundant throughout the world, particularly in pristine unpolluted habitats, growing on soil, rocks, leaves, tree bark, other lichen, and even the backs of tortoises.

–> Lichens grow slowly, but they can live for hundreds and possibly thousands of years and occur in 3 basic shapes:
–> “Foliose” lichens are leaflike, with margins that grow free from the substrate.
–> “Crutose” lichens grow appressed to their substrates and may extend into the substrate for several millimeters.
–> “Fruticose” lichens are either erect or are hanging cylinders.
–> Lichens create soil from weathered rocks, and lichens containing nitrogen fixing cyanobacteria provide significant amounts of usable nitrogen to nutrient poor environments. – Ex; animal eat lichens, used as nests, foods, dyes, clothing, perfumes, medicines, litmus of indicator paper, assays for air pollution.
–> In the preceding..fungi are chemoheterotrophic yeasts and molds that function primarily to decompose and degrade dead organisms.

–> coenocytic (aseptate)
–> Rhizopus

–> septate; some associated with cyanobacteria or green algae to form lichens
–> Claviceps, Neurospora, Penicillium, Saccharomyces, Tuber

–>septate
–> Agaricus, Amanita, Crytococcus.

–> the Romans used the word “alga” to refer to any simple aquatic plant, particularly one found in marine habitats. – refers to simple, eukaryotic, phototrophic, carry out oxygenic photosynthesis using chlorophyll a.
–> Algae are not a unified group, rather, they differ widely in distribution, morphology, reproduction, and biochemical traits. – algae can be found ingdoms Alveolata, Euglenozoa, Stramenopila, Rhodophyta, and Plantae. – the study of algae is phycology.

–> Even though some algae grow in such diverse habitats as in soil and ice, in intimate association with fungi as lichen, and on plants, most algae are aquatic, living in the photic zone of fresh, brackish, and salt bodies of water. – their primary photosynthetic pigment chlorophyll a captures red light.

–> Algae can be unicellular or colonial, or they can have simple multicellular bodies, which are commonly composed of branched filaments or sheets. – Many of the larger marine algae are buoyed in the water by gasfilled bulbs called “pneumocysts”

— In unicellular algae, asexual reproduction involves mitosis followed by cytokinesis.
–> Multicellular algae may reproduce asexually by fragmentation, in which each piece of a parent alga develops into a new individual, or by motile or nonmotile asexual spores. – every cell in the reproductive structures of the alga becomes a gamete, a feature distinguishable from all other photosynthetic eukaryotes.
–> Many multicellular algae reproduce sexually with an “alternation of generations” of haploids and diploid individuals. – both haploid and diploid algae may reproduce asexually as well.

–> The classification of algae is not yet settled. – Historically, taxonomists have used differences in photosynthetic pigments, storage products, and cell wall composition to classify algae into several groups that are named for the colors of their photosynthetic pigments: green algae, red algae, brown algae, golden algae, and yellow-green algae.

–> “Chlorophyta” are green algae that share numerous characteristics with plants. – they have chlorophylls a & b and use sugar and starch as food reserves. – cell walls are cellulose or glycoprotein or lack walls. – 18S rRNA sequences.
–> Most green algae are unicellular or filamentous and live in freshwater ponds, lakes, and pools, where they form green to yellow scum.
–> “Prototheca” is an unusual green alga in that it lacks pigments, making it colorless. – causes skin rashes. – “Codium” is a member of a group of marine green algae that do not form cross walls after mitosis, its entire body is a single, large, multinucleate cell, and also used as pepper. – “Trebuoxia” is the most common alga found in association with fungi in lichens.

–> Algae of division “Rhodohpyta”, which had been placed historically in Kingdom Plantae and then Protista, are now in their own kingdom, Rhodophyta. – characterized by the red accessory pigment “phycoerythrin”, the storage molecule glycogen, aka floridean starch, cell walls of “agar” or “carrageenan”, sometimes supplemented with calcium carbonate; and nonmotile male gametes called “spermatia”. – Most red algae are marine.
–> The gel-like polysaccharides agar and carrageenan, once they have been isolated from red algae such as “Gelidium” and “Chondrus” are used as thickening agents for the production of solid microbiological media and numerous consumer products, including ice cream, toothpaste, syrup, salad dressings, and snack foods.

–> The “Phaeophyta” are in kingdom Stramenopila based in large part on their gametes being motile by means of 2 flagella one whilike and one with hollow projections giving it a hairy appearance. – they have chlorophylls a and c, carotene, and brown pigments called “xanthophylls”. – most are marine organisms as giant kelps, such as “Macrocytis” that surpass the tallest trees.
–> Brown algae use the polysaccharide “laminarin” and oils as food reserves and have cell walls compsed of cellulose and “alginic acid”, a thickening agent in medicine in the preparation of dental impressions.
–> A brown algal spore is motile by means of one “hairy” flagellum and one whiplike flagellum.

–>”Chrysophyta” is a group of algae that are diverse with respect to cell wall composition and pigments. – they are unified in using the polysaccharide “chrysolaminarin” as a storage product. – One taxon of chrysophytes, Bacillariophyceae the “diatoms” are unique in having silica cell walls composed of 2 halves called “frustules” that fit together like a Petri dish.
–> Most chrysophytes are unicellular or colonial. All chrysophytes contain more orange colored “carotene” pigment than they do chlorophylls a and c; two major classes chrysophytes > “golden algae” and “yellow green algae”.
–> Diatoms are a major component of marine “chytoplankton: free floating photosynthetic microorganisms that form the basis of food chains in the oceans. – Ex; “diatomaceous earth” are used as pesticide against harmful insects and worms, polishing compounds, detergents, and paint removers, firebrick, soundproofing products, swimming fool filters, and reflective paints.
–> In summary, algae are unicellular or multicellular photoautotrophs characterized by sexual reproductive structures in which every cell becomes a gamete.

–> Plantae
–> shlorophylls a and b, carotene, xanthophylls
–> sugar, starch
–> cellulose or glycoprotein; absent in some
–> fresh, brackish, and salt water; terrestrial
–> spirogyra, protetheca, codium, trebouxia

–> Rhodophyta
–> Chlorphyll a, phycoerythrin, phycocyanin, xanthophylls
–> Glycogen (floridean starch)
–> agar or carrageenan, some with calcium carbonate
–> mostly salt water
–> chondrus, gelidium, Antithmnion

–> Stramenopila
–> Chlorophylls a, c1, and c2, carotene, xanthophylls
–> chrysoaminarin, oils
–> cellulose, silica, calciu carbonate
–> fresh, brackish, and salt water; terrestrial; ice
–> Stephanodiscus

–> Stramenopila
–> Chlorophylls a and c, carotene, xanthophylls
–> Laminarin, oils
–> cellulose and alginic acid
–> Brackish and salt water
–> Macrocytis

–> Alveolata
–> Chlorphylls a, c1, c2, carotene
–> Starch, oils
–> Cellulose
–> Fresh, brackish, and salt water
–> Gymnodinium, Gonyaulax, Pfiesteria

–> Euglenozoa
–> Chlorophylls a and b, carotene
–> Paramylon, oils, sugar
–> absent
–> Fresh, brackish, and salt water; terrestrial
–> Euglena

–> Scientists once classified the microbes commonly known as “water molds” as fungi because they resemble filamentous fungi in having finely branched filaments. – they are not true molds and are not fungi.
–> they have tubular cristae in their mitochondria.
–> they have cell walls of cellulose instead of chitin.
–> their spores have 2 flagella, one whiplike and one hairy.
–> they have true diploid bodies rather than haploid bodies.
–> Because water molds have “hairy” flagella and certain similarities in rRNA sequence to sequences of diatoms, other chrysophytes, and brown algae, taxonomists classify all these organisms in kingdom Strmenopila.
–> Water molds decompose dead animals and return nutrients to the environment.

–> Microbiologists are interested also in 2 other groups of eukaryotes, although they are not microorganisms. – the first group are the parasitic “helminths”, aka parasitic worms.
–> Microbiologists are also interested in “arthropod vectors”, animals that carry pathogens and have segmented bodies, hard external skeletons, and jointed legs. – some are “mechanical vectors”. – other are “biological vectors”, meaning they merely carry pathogens;
–> Disease vectors belong to 2 classes of arthropds: “Arachnida and Insecta”.

–> All adult “arachnids” have four pairs of legs. – Both “ticks” and “mites” go through a six-leg stage when they are juveniles, but they display the characteristic eight legs as adults.
–> Ticks are the most important arachnid vectors. – Some tick-borne diseases are Lyme disease, Rocky Mountain spotted fever, tularemia, relapsing fever, and tick borne encephalitis.
–> Parasitic mites of humans live around the world, wherever humans and animals coexist.

–> A adults, all “insects” have three pairs of legs and three body regions, head, thorax & chest), and abdomen.
–> The fact that many insects can fly has epidemiological implications. Flying insects have broader home ranges than nonflying insects, and some migrate, making control difficult.
–> “Fleas” are small, vertically flattened, wingless arthropods that are found worldwide, though some species have geographically limited ranges. – “Dipylidium”, the most significant microbial disease transmitted by fleas is plague, carried by rat fleas.
–> “Lice” are parasites that can also transmit disease. – they are horizontally flat, soft bodied, wingless insects found worldwide among humans and their habitations.