BI203 chapter 12: The Eukaryotes

3.Give some fungal enzymes which make of them "decomposers" ?

1. Through the use of extracellular enzymes like cellulases, fungi are able to decompose the hard part of plants which cannot be digested by animals 2. Nearly all plants depend on a fungi known as mycorrhizae, which helps their roots absorb minerals and water from soil 3. Fungi farming ants cultivate fungi that breakdown cellulose and lignin from plants, providing them with glucose that the ants can digest

23 continued

2. Cestodes, or tapeworms, are intestinal parasites. The head of a cestode, called the scolex, has suckers for attaching to the intestinal mucosa. Some species also have hooks for this purpose. However, tapeworms do not ingest the tissues of their hosts; they actually lack a digestive system. To obtain nutrients, they absorb food through their cuticle. Their body consists of segments called proglottids, which are continaullyh produced by the neck region of the scolex. Every mature proglottid contains both male and female reproductive organs. a. Taenia saginata, the beef tapeworm, is an example of a cestode. It lives in humans and can reach a length of 6 meters. Below is the life cycle of a cestode: ii. Nematodes, or roundworms, are cylindrical and tapered at each end. They have a complete digestive system, with a mouth, an intestine, and an anus. Some species of nematodes are free-living in soil and water, and others are parasites on plants and animals. Some nematodes pass their entire life cycle, from egg to adult, in a single host. Nematode infections of humans can be divided into two categories: those in which the egg is infective, and those in which the larva is infective. 1. Eggs infective for humans: the pinworm Enterobius vermicularis spends its entire life in a human host. Adult pinworms are found in the lg. intestine, from where female pinworms migrate to the anus to depost eggs on the perianal skin. These eggs can be ingested by the host or by another person exposed through contaminated clothing or bedding. Thus the eggs are infective for humans. 2. Larvae infective for humans: The adult hookworm Necator americanus lives in the small intestine of humans; the eggs are excreted in feces. The larvae then hatch in soil, where they feed on bacteria. They then enter a host by penetrating the host's skin, where it next enters a blood or lymph vessel for transport to the lungs. It is then coughed up into the sputum, swallowed, and carried to the small intestine.

24 Define arthropod vectors:

: arthropods are animals characterized by segmented bodies, hard external skeletons, and joined legs. With nearly 1 million species, it ist helargest phylum in the animal kingdom. Arthropods that carry pathogenic microorganism are called arthropod vectors. a. Mites, ticks, lice, fleas, and flies are some important arthropod vectors of human disease. Some vectors are just a mechanical means of transport for a pathogen, e.g. houseflies picking up pathogens on their feet and transporting them. Other vectors multiply the parasites within themselves, so that the parasite accumulates in the vector's feces or saliva. The spirochete that causes Lyme disease, Borrelia burgdorferi, is transferred in this manner, along with the West Nile virus. i. Plasmodium is an example of a parasite that requires that its vector also be the definitive host. Plasmodium can sexually reproduce only in the gut of an Anopheles mosquito. It is introduced into a human host with the mosquito's saliva, which acts as an anticoagulant that keeps blood flowing.

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

a. A tick is in the phylum arthropod, class Arachnida (meaning it has 8 legs). It is not an insect. The Ixodes tick carries Lyme disease. b. Mosquitos is in the phylum arthropod, class insecta (meaning they have sig legs). Mosquitos transmit the West Nile virus.

20 Distinguish between cyst and trophozoite:

a. A trophozoite is a protozoa in its feeding and growing stage, when it is feeding upon bacteria and small particulate nutrients. i. Under certain adverse conditions, some protozoa produce a protective capsule called a cyst. A cyst permits the organism to survive when food, moisture, or oxygen are lacking, when temperatures are not suitable, or when toxic chemicals are present. A cyst all enables a patristic species to survive outside a host. A cyst is very similar to an endospore, in that the bacteria is not growing or feeding when cystic. It is merely lying dormant and waiting for the proper supply of nutrients.

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

a. Algae are mostly relatively simple eukaryotic photoautotrophs; they lack the tissues of plants. They are classified according to their rRNA sequences, structures, pigments, and other qualities. i. Most algae are found in the ocean. ii. Algae absorb nutrients from the water over their entire surfaces. iii. All algae can reproduce asexually, but sexual reproduction can also occur in some species. iv. For nutrition: algae is a common name for several phyla; most algae are photosynthetic; however, there are some chemoheterotrophs v. The body of a multicellular alga is called a thalus. The cells covering the thallus can carry out photosynthesis, but the thallus lacks the conductive tissue (xylem and phloem) of vascular plants. The surrounding water supports the algal thallus in most algae, but some algae are buoyed by a float, gas-filled bladder called a pneumatocyst. b. Role of algae in ecosystem: algae are an important art of any aquatic food chain because they fix CO2 into organic molecules that can be consumed by chemoheterotrophs. They do this by using the energy produced in photophosphorylation to convert CO2 into carbohydrates, with O2 as a byproduct. It is estimated that 80% of the earth's oxygen is produced by planktonic algae. i. Much of the world's petroleum was formed from diatoms and other planktonic organisms that lived several million years ago. When these organisms died, their organic molecules did not decompose; heat and pressure altered the oils stored in the cells so that oxygen and other elements were elimanted. ii. Many unicellular algae are symbionts in animals.

15) Fungal diseases and examples for each:

a. Any fungal infection is called a mycosis. Mycoses are generally chronic (long-lasting) infections because fungi grow slowly. They are divided into 5 groups according to the degree of tissue involvement and the mode of entry into the house: i. Systemic mycoses are fungal infections deep within the body. They are not restricted to any particular region of the body but can affect a # of tissues and organs. They are usually caused by fungi that live in soil; inhalation of spores is the route of transmission. Histoplasmosis (spelunker's lung) is an example of a systemic mycosis. ii. Subcutaneous mycoses are fungal infections beneath the skin caused by saprophytic fungi that live in soil and on vegetation. Infection occurs by direct implantation of spores or mycelial fragments into a puncture wound. Sporotrichosis is an example of a subcutaneous mycosis. iii. Cutaneous mycoses are fungal infections that infect only the epidermis, hair, and nails. They are caused by dermatophytes, which secrete keratinase, an enzyme that degrades keratin. Ring worm is an example of a cutaneous mycoses. iv. Superficial mycoses are localized along hair shafts in in superficial epidermal cells. They are prevalent in tropical climates. Tinea versicolor, which causes a browning of the skin, is an eample. v. Opportunistic mycoses are harmless in a normal habitat but become pathogenic in an immunocompromised host. Pneumocystis (which causes death in aids patients) is an example.

22 What are the three phyla of Algae and their pigment. Example for each.

a. Brown algae, or kelp, are macroscopic and can reach lengths of 50m. Most brown algae are found in coastal waters. A thickener, algin, extracted from their cell walls and is used in a wide variety of nonfood goods. b. Red algae have delicately branched thalli and can live at greater ocean depths than other algae. Their red pigments enable red algae to absorb the blue light that penetrates deepest into the ocean. The agar used in microbiological media is extracted from red algae. (Also MacDonald's uses red algae's carrageenan to thicken its desserts.) c. Green algae have cellulose cell walls, contain chlorophyll a and b, and store starch, as plants do. They are believed to have given rise to terrestrial plants. Most green algae are microscopic, although they may be either unicellular or multicellular. d. Diatoms, donoflagellates, and water molds are also phyla of algae (but I think she wants us to know the first three). i. Diatoms are uniceullar or filamentous algae with complex cell walls that consist of pectin and a layer of silica. They can produce domoic acid, a toxin that has caused deaths from eating mussels. ii. Dinoflagellates are unicellular algae collectively called plankton (i.e. free floating organisms). Some dinoflagellates produce neurotoxins. iii. Water molds, or oomycota, are decomposers. They form the cottony masses on dead algae and animals, usually in fresh water.

23 List the characteristics of parasitic helminthes. Describe the sub-phyla and their classes if any. Give an example of each.

a. Characteristics: helminths are multicellular eukaryotic animals that generally possess digestive, circulatory, nervous, excretory, and reproductive systems. Parasitic helminths must be highly specialized to live inside their hosts. The following generaliations distinguish parasitic helminthes from their free-living relatives: i. They make lack a digestive system: they can absorb nutrients from the host's food, body fluids, and tissues ii. Their nervous system is reduced: they do not need an extensive nervous system because they do not have to search for food or respond much to their environment (since the environment within a host is fairly constant) iii. Their means of locomotion is occasionally reduced or completely lacking: because they are transferred from host to host, they do not need to search actively for a suitable habitat iv. Their reproductive system is often complex: an individual produces large numbers of eggs, by which a suitable hose is infeted b. There are two sub-phyla of helminthes: Platyhelminthes and nematode i. Platyhelminthes, or flatworms, parasitic helminths, are dorsoventrally flattened. There are two classes of parasitic flatworms, trematodes and cestodes, which cause disease or developmental disturbances in a wide variety of animals. 1. Trematodes, also called flukes, usually have flat, leaf-shaped bodies with a ventral sucker and an oral sucker, both of which serve to hold the organism in place. Flukes obtain food by absorbing it through their nonliving outer covering, their cuticle. They are given common names according ot the tissue of the definitive host in which they live. An example is the lung fluke, Paragonimus westermani, which occurs throughout the world, including the US and Canada. It lives in the bronchioles of humans and other mammals.

13 What is dimorphism?

a. Dimorphism is the ability to exhibit two forms of growth (e.g. as a mold or as a yeast), depending on temperature or CO2 concentration. It is most common in pathogenic species.

16) List the defining characteristics of protozoa:

a. Protozoa (meaning "first animal") are unicellular, eukaryotic chemoheterotrophs. They inhabit water and soil and have two stages - a cystic stage and a trophozoite stage. Some protozoa are part of the normal microbiota of animals. i. Protozoa reproduce asexually and sexually. Asexually, they use budding, fission, and schizogony (multiple fission). Sexually, they use conjugation. ii. Encystment occurs when, under adverse conditions, protozoa produce a protective capsule called a cyst. A cyst permits the organism to survive when food, moisture, or xygen are lacking. It also enable a patristic protozoa to survive outside a host. iii. Nutritionally, protozoa are mostly aerobic heterotrophs, although some are capable of anaerboc growth. All protozoa live in areas with a large supply of water.

19 Differentiate between and intermediate host and a definitive host. Apply these two terms to the reproductive cycle of plasmodium malaria and fluke:

o In plasmodium vivax, the Apicomplexa that causes malaria, asexual reproduction occurs in the liver (making the liver the intermediate host) while sexual reproduction occurs in the intestine of an Anopheles mosquito, after the mosquito has ingested gametocytes (making the mosquito the definitive host). o In Paragonimus westermani, a trematode (fluke), sexual reproduction occurs in a human (making the human its definitive host) while asexual reproduction occurs in a snail (making it its first intermediate host). It can also have a second intermediate host, a crayfish, which is eaten by humans, continuing the cycle.

12. Discuss different morphologies of fungi. Examples

o Molds and fleshy fungi - the thallus (body) of molds of fleshy fungi consist of long filaments of cells joined together called hyphae. The hyphae can grow to immense proportions. When environmental conditions allow the hyphae grows to form a filamentous mass called mycelium, which is visible to the unaided eye. • Eg. Penicillum notatum, Aspergillus flavus o Yeasts - are non filamentous, unicellular fungi that are typically spherical or oval. Like molds widely distributed in nature and found mostly in white powdery coating of fruits and leaves. Budding yeasts like Saccharomyces divide unevenly. Fission yeasts like Candida albicans divide evenly to produce two new cells. • Eg. Saccharomyces cereviciae o Dimorphic fungi - some fungi, most notably the pathogenic species, display dimorphism, two forms of growth. These fungi can grow either as mold or yeast. The form of growth depends on temperature and CO2. Eg. Candida albicans growing as yeast in 37" temperature and Histoplasma capsulatum growing as mold in 25" temp. Due to CO2 effect, on top of media growing as yeast and stabbed media growing as mold • Eg. Mucor indicus, Histoplasma capsulatum 13) What is dimorphism:

2.Contrast saprophyte from parasite.

o Saprophytes obtain their nutrients from dead matter. o Parasites derive their nutrients from a living host.

11. What are lichens? Describe the role of the fungus and the alga or photosynthetic bacteria (cyanobacterial) in lichen

• A lichen is a combination of a green alga (cyanobacterium) and a fungus. Lichens are placed in the kingdom fungi and are classified according to the fungal partner, most often an ascomycete. The two partners exist in a mutual relationship in which both benefit; the lichen is very different from the alga or the fungus growing alone; if the partners are separated, the lichen no longer exists. Fungal hyphae grow around algal cells, forming the medulla (thallus). The hyphae also project below the lichen body to form rhizines, or holdfasts, as well as a cortex (protective covering over the algal layer). o when an algae is associated with a fungus, the algal plasma membrane is more permeable and picks up more products of photosynthesis (giving them to the fungus). The algae also benefits in that it receives protection from dessication through the cortex and ability to attach through the rhizines.

4.Discuss four different ways fungi are beneficial to mankind 4 ways and fungi can harm mankind.

• Beneficial 1. Food production • Saccharomyces cerevisiae in bread and wine production 2. Fermentation and industrial use • Aspergillus niger is used in citric acid production (for foods and beverages) • Trichoderma is used commercially to produce the enzyme cellulose, which is used to remove plant cell walls to produce a clear fruit juice. 3. Medical use • Saccharomyces cerevisiae in hepatitis B vaccine production • Taxomyces in taxol production (anticancer drug) 4. Biological pest control • Entomophage in moth control • Coniothrium minitans feeds on fungi that destroy soybeans and other bean crops. • Harmful 1. Causes breakdown of food products. E.g. Rhizopus stolonifer, which causes black bread mold. 2. Fungal infections on the epidermis, hair, and nails, called dermatomycoses, caused by dermatophytes, wich secrete an enzyme that degrades keratin. 3. Opportunistic pathogens such as pneumocystis (the most common life-threatening infection in AIDs patients), which afflicts indivials with compromised immune systems 4. Production of mycotoxins such as ergot or aflatoxin

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

• Characteristics: Fungi are eukaryotic; they have sterols present in their cell membrane, are capable of sexual and asexual reproduction, are either aerobic or facultatively anaerobic, and are heterotrophic (they cannot fix carbon themselves and rely on organic carbon sources for growth). They are also chemotrophs - they obtain energy through the oxidation of electron donors. All fungi, except yeasts, are multicellular. Thus they are chemoheterotrophs. o Fungal colonies are described as vegetative structures because they are composed of the cells involved in catabolism and growth. The three types of fungi are molds and fleshy fungi, yeasts, and dimorphic fungi. • Role in the ecosystem: fungi are important in the ecosystem and food chain because they decompose dead plant matter, thereby recycling vital elements. By the use of extracellular enzymes like cellulose, fungi are primary decomposers of hard parts of plants which can't be digested by animals.

14 Give three examples of dimorphic fungi and the factors that control the dimorphism:

• Coccidioides immitis is a dimorphic fungus that causes coccidioidomycosis, a disease endemic to the southwestern United States. The mold form of the fungus grows in arid soil and produces thick-walled, barrel-shaped asexual spores called arthrospores by a fragmentation of its vegetative hyphae. After inhalation, the arthrospores germinate and develop into endosporulating spherules in the terminal bronchioles of the lungs. • Histoplasma capsulatum is a dimorphic fungus that causes histoplasmosis, a disease commonly found in the Great Lakes region and the Mississippi and Ohio River valleys. The mold form of the fungus often grows in bird or bat droppings or soil contaminated with these droppings and produces large tuberculate macroconidia and small microconidia • Blastomyces dermatitidis- caused by Blastomyces dermatitidis, is common around the Great Lakes region and the Mississippi and Ohio River valleys. Blastomyces dermatitidis produces small condidiospores and grows actively in bird droppings and contaminated soil. When spores are inhaled or enter breaks in the skin, they germinate and the fungus grows as a yeast having a characteristic thick cell wall. It is diagnosed by culture and by biopsy examination.

8. Different types of asexual spores and examples of each

• Filamentous fungi can reproduce asexually by fragmentation of hyphae. In addition, they are capable of both sexual and asexual reproduction through the formation of spores. • A bacterial spore is a form of vegetative survival mechanism, but the fungal spore can germinate into a new mold once it detaches from the parent. Thus the fungal spore is a true reproductive spore unlike bacterial spore. However they are not as strong in surviving extreme conditions as bacterial spores. • Asexual spores are formed by the hyphae of one organism. When they germinate through mitosis they become organisms that are identical to the parent. • Two types of asexual spores are produced by fungus; Conidiospore and Sporangiospore. • Conidiospore or conidium (conidia) - unicellular or multicellular spore that is not enclosed in a sac. They are produced in a chain at the end of a conidiophore. Such are produced by Aspergillus. Arthroconidia are conidia formed by the fragmentation of septate hyphae into single, slightly thickened cells. Eg. Coccidioides immitis • Balastoconidia consists of buds coming off parent cell. Eg. Candida albican's and Cryptococcus • A Chalmydoconidium is a thick walled spore formed by rounding and enlargement within the hyphae segment. Found in the yeast Candida albicans o Sporangiospore form with sporangium, or a sac at the end of aerial hyphae called the sporangiophore. The sporangium can contain hundreds of sporangiospores. Eg. Rhizopus

7. Classify fungi: according to shape and to sexual spores

• Fungal colonies are described as vegetative structures because they are composed of cells involved in catabolism and growth. When we classify fungus according physical characteristics (shape or morphology) we have three classifications. 1. Shape or morphology o Molds and fleshy fungi - the thallus (body) of molds of fleshy fungi consist of long filaments of cells joined together called hyphae. The hyphae can grow to immense proportions. When environmental conditions allow the hyphae grows to form a filamentous mass called mycelium, which is visible to the unaided eye. Eg. Penicillum notatum, Aspergillus flavus o Yeasts - are non filamentous, unicellular fungi that are typically spherical or oval. Like molds widely distributed in nature and found mostly in white powdery coating of fruits and leaves. Budding yeasts like Saccharomyces divide unevenly. Fission yeasts like Candida albicans divide evenly to produce two new cells. Saccharomyces cereviciae o Dimorphic fungi - some fungi, most notably the pathogenic species, display dimorphism, or two forms of growth. These fungi can grow either as mold or yeast. The form of growth depends on temperature and CO2. Eg. Candida albicans grows as yeast in 37" temperature and Histoplasma capsulatum grows as mold in 25" temp. Due to CO2 effect, on top of media growing as yeast and stabbed media growing as mold 2. Classification based on sexual spore o Zygomycota or conjugating fungi are saprophytic fungi that have coenocytic hyphae. The sexual spores are zygospores, large spore enclosed in a thick wall. Fusion of haploid cells produces zygospores. • This type of spore results from the fusion of the nuclei of two cells that is morphologically similar to each other. Ex. Rhizopus stolonifer - common black beard mold. (Opportunistic systemic mycoses, like Rhizopus mucor) o Ascomycota - or sac fungi, include molds with septate hyphae and some yeast. Produce ascopore and frequently Conidiospore. Their asexual spores are usually conidia produced in long chains from conidiophore. Conidia mean dust and these spores freely detach from the chain at the slightest disturbance and float in air. • The ascopore results from the fusion of nuclei of two cells that can be either morphologically similar or dissimilar. These spores are produced in a sac like structure called an ascus. The members of this phylum are called sac fungi because of the ascus. Eg. o Basidiomycota - club fungi, also possesses septate hyphae. This phylum includes fungi that produce mushrooms. Basidiospores are formed externally on a base pedestal called a basidium. There are usually four Basidiospores per basidium. Eg. Cryptococcus neoformans, systemic mycoses o Anamorphs are asexual fungi that have lost the ability to produce sexually. The fungi we have seen so far are teleomorphs; they produce both sexual and asexual spores. Based on their rRNA sequencing, it is possible to classify them and most are Ascomycota and some are Basidiomycota. Eg. Penicillum, Candida albicans

17 What criteria are used for their classification:

• Mode of motility • Cell structure

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

• Mycotoxin is a toxin produced by a fungus. Some of these toxins, like phalloidin and amaniti (produced by amanita plalloides mushroom [death cap]) are so potent that ingestion of the mushroom might result in death. • Aflatoxin is a carcinogenic toxin produced by the mold Aspergillus flavus. This mold usually grows on grains and plants (like on recalled peanut butter); its ingestion might lead to the toxin producing mutagenic reaction in the body, which is the cause of its carcinogenic nature. • Ergot - a toxin produced in sclerotia (the highly resistant portion of the mycelia of the fungus that can detach) by the fungus claviceps purpurea that causes ergotism, which was common in the middle aged. The toxin itself, ergot, is an alkaloid that causes hallucinations resembling LSD and also constricts capillaries and can cause gangrene of the limbs by preventing proper blood circulation in the body. Though it still occasionally occurs in plants these days, modern milling removes the sclerotia.

9. What are pseudohyphae? Relate this to Candida Albican's pathogenicity.

• One yeast cell can produce up to 24 daughter cells by budding. Some yeasts form buds that fail to detach themselves. Instead, the buds form a short chain of cells called pseudohyphae. o Candida albicans attaches to human epithelial cells as yeasts but usually requires pseudohyphae to invade deeper tissue. The pseudohyphae are resistant to phagocytosis and may therefore be a factor in pathogenicity.

18 Describe the outstanding characteristics of the phyla of protozoa discussed in class. Give an example of pathogenic protozoan for each phylum and the means used for movement if any:

• Sarcodina are characterized by their movement using pseudopodia, or "false feet." While few are pathogenic, one member of this group, Entamoeba histolytica does cause disease. These pathogens live inside animals and cause amoebic dysentery through the lysis of human intestinal cells. Infection occurs through ingestion of drinking water with contaminated feces, hands, food, or oral-anal intercourse and has an annual worldwide mortality of 100,000. Diagnosis of an E. histolytica infection usually involves microscopic examination of fecal matter. • Mastigophora are singled celled and move using flagella. Trichomonas vaginalis causes the most common protozoan disease called trichomoniasis. This organism is transmitted via sex and occurs most frequently in people with a preexisting STD. Interestingly, this organism lacks the cyst stage and dies quickly when exposed to the environment. • Ciliophoria move using cilia. Balantidium coli, a human parasite that causes a rare type of severe dysentery called balantidiasis, is of the class ciliophora. It is acquired by the ingestion of cysts; as they enter the intestine, trophozoites are released. The trophozoites destroy host cells and feeds on the host cell fragments. Before excretion from the host in the feces, the organism takes the cyst form. • Apicomplexa are non-motile. Plasmodium, a sporoza, is a blood parasite that causes malaria and is spread via the mosquito. Malaria is one of the most, if not the most, prevelant microbial diseases in the world, with up to 10% of the world's population affected and 300-500 million new cases a year. Cryptosporidium is another non-motile protozoan that can be transmitted from the feces of cows, dogs, rodents, and cats to a human host. It reproduces in the lining of the small intestine and causes cryptosporidiosis, a gastrointestinal disorder characterized by diarrhea lasting ten-to-fourteen days. It is commonly transmitted via contaminated drinking water and recreational water (lakes, streams, pools) containing the cyst form of Cryptosporidium

6. The two types of hyphae (coenocytic and septic)

• Septate hyphae - In most molds the hyphae contain cross-walls called septa (septum) which divide them into distinct uninucleate (one nucleus) cell like units. • Coenocytic hyphae - in few classes of fungi the hyphae contain no septa and appear as long continuous cells with many nuclei. o Even in fungus with septate hyphae, there are usually openings in the septa that make the cytoplasm of adjacent cells continuous, these are actually coenocytic organisms.

10. Discuss sexual reproduction in fungi

• Sexual spores result from the fusion of nuclei from two opposite mating strains of the same species of fungus. Fungi produce sexual spores less frequently than asexual spores. • A fungal sexual spore results from sexual reproduction, which consists of three phases o Plasmogamy - a haploid nucleus of a donor cell (+) penetrates the cytoplasm of a recipient cell (-) o Karyogamy - the (+) and (-) nuclei fuse to form a diploid zygote nucleus o Meiosis - the diploid nucleus gives rise to haploid nuclei (sexual spores) some of which may be genetic recombinants • The sexual spores produced by fungi characterize the phyla. In lab setting most fungi exhibit only asexual spores. • Consequentially, clinical identification is based on microscopic examination of asexual spores.