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1. Define the following terms: Fertilization, cleavage, Parthenogenesis, blastula, morula, gastrula.
- Fertilization: When sperm enters egg
- Cleavage: the process of nucleus and cell division in the zygote
- Parthenogenesis: Egg that multiplies and becomes organism WITHOUT sperm (eg. Rotifers, crustaceans, insects, fishes, desert lizards, etc)
- morula: “solid” ball of cells
- blastula: “hollow” ball of cells (called a blastocyst in humans)
- Blastocoel is the empty space within the blastula (and gastrula)
- Gastrula: cells begin to invaginate and form the archenteron (embryonic gut)
- Blastopore (the invagination of the gastrula) will eventually become either the mouth or the anus
Define the following terms: gastrulation, neurulation, organogenesis, gametes, acrosomal sac, zygote
- Gastrulation: formation of gastrula (formation of germ layers)
- Neurulation: formation of nervous system (formation of neurula)
- Organogensis: formation of organs
- Gametes: sperm and egg (only haploid cells in body)
- Acrosomal sac: layer on top of head of sperm which dissolves the outside of the egg during fertilization
- Zygote: fertilized egg
What are the main events of reproduction (stages) in order? (Not human, just stages)
Gamete formation -> fertilization -> cleavage -> gastrulation -> neurulation -> organogensis -> growth
2. Define the following types of cleavage with one example: Spiral, radial, rotational, discoidal, and superficial.
- Spiral: the first two planes of cleavage are vertical and produce blastomere of equal size. The third cleavage is horizontal and blastomere are unequal. [eg. mollusk (snail, octopus) and anneleids (earthworm, leech)]
- Radial: The first two planes of cleavage are horizontal and produce equal blastomere. The third plane of cleavage is also horizontal and blastomere are unequal. [ eg. Starfish and frog.]
- Rotational: After the second cleavage one pair of blastomere comes to lie at right angles to the others. [eg. Humans.]
- Discoidal: The cleavage is restricted to a small disc at one end of the embryo (middle), the rest is yolk. [eg. Birds.]
- Superficial: Yolk is in the center and cleavage is in the outer surface. [eg. Arthropods.]
3. What are the differences between Deuterostome and Protostome animals? Humans?
- Protostomia: “mouth first” – blastopore becomes mouth. Most have spiral cleavage, are schizocoelous (coelum is formed by splitting cells), and mosaic embryo cleavage.
- Deuterostomia: “mouth second” – blastopore becomes anus. Most have radial cleavage, are entercoelous (coelum is formed by outpocketing cells), and regulative embryo cleavage.
- Note: human is deuterostome, rotational cleavage, and schizocoelus
4. What are the different types of yolk, give an example of each?
- Isolecithal: small amount of yolk is approximately equal to amount of cleavage [eg. Starfish and human]
- Mesolecithal: moderate amount of yolk (more than isolethical) [eg. Frog]
- Telolecithal: huge yolk [eg. Birds]
- Centrolecithal: yolk is in center surrounded by cleavage, large amount of yolk [eg. Insects]
5. What are the three germ layers and what do they become?
- Ectoderm: (blue on models) epidermis and associated structures (hair, nails, etc), brain and nervous system
- Endoderm: (yellow on models epithelial cells of G.I. tract, glands including liver and pancreas, inner lining of respiratory tract
- Mesoderm: (red on models) notochord, outer covering of internal organs, muscles, excretory system, dermis, bones and cartilage, circulatory system (heart, blood vessels, etc)
6. What is the difference between diploblastic animal and triploblastic animal?
- Triplobastic: has 3 germ layers (ectoderm, endoderm, mesoderm) – this is the majority of animals
- Diploblastic: has 2 germ layers (ectoderm, endoderm) – these are simple animals that lack body cavities and true organs (eg. Jellyfish)
- Note: Tripoblastic animals are said to be evolved from diploblastic animals
7. What are the differences between Schizocoelous and Enterocoelous animals?
- Schizocoelous: coelum is formed by splitting cells (scattered cells)
- Entercoelous: coelum is formed by outpocketing cells
- Note: coelum is the space between dermis and gut surrounded by mesoderm
8. What is the difference between holoblastic and meroblastic animal?
- holoblastic: The entire cell divides in the absence of large concentration of yolk (isolecithal and Mesolecithal) leads to radial, spiral, and rotational cleavage (eg starfish)
- meroblastic: Only part of the cell can divide due to the presence of large concentration of yolk (telolecithal and centrolecithal) leads to discoidal and superficial cleavage. (eg frog)
9. What is metamorphosis?
Sharp changes in embryonic development (for example, a beetle looks completely different from its pupa)
10. What are the similarities and differences between regulative and mosaic cleavage?
- Regulative: if you separate the cells of a morula and they become normal animals
- Mosaic: if you separate the cells of a morula and they become defective animals (because the cells are communicating, even at such an early stage)
11. Explain animal cloning and the term totipotent?
- totipotent: one cell can become the entire organism (egg is the only cell in the human body BUT it is haploid, so it requires a sperm OR the replacement of its haploid nucleus with the nucleus from a somatic diploid cell.
- Dolly’s cloning process: remove nucleus from an egg (n) of black headed sheep, replace nucleus with nucleus from mammary cell (2n) of white headed sheep then grow in petri dish until it becomes a blastula then implant it into the black headed sheep. When the sheep was born it was 95% identical to white headed sheep (mitochondria were different because they came from black headed sheep). This was the first clone created of a mammal.
12. Explain stem cell and multipotent?
- Multipotent (pluripotent) cells: stem cell that can drive to multiple cell types (but not ALL cell types)
- Adult stem cells: (bone marrow, fat cells) cells from body that can be cultured into specific cell-types and surgically implanted. Very difficult to achieve, but there is no risk of rejection.
- Embryonic stem cells: (cells from inner mass cells, not trophoblast, of blastocyst) that can be cultured into specific cell types. Easier process than adult stem cells BUT runs the risk of rejection because it comes from a different person.
- Note – embryonic stem cells received from fertility clinic after successful implantation from “leftovers”
13. Diagram the differentiation of the germ layers?
14. What is the differentiation of brain?
16. What is the function of amnion, allantois and chorion?
- Amnion: a sac full of fluid that surrounds the embryo and acts as a shock absorber to protect it.
- Allantois: highly vascularized area that connects with embryo to bring in nutrients and remove wastes
- Chorion: a second sac that surrounds the amnion and the allantois
- Chorioallantoic membrane: alantois and chorion merge later in development to create the chorioallantoic membrane
- Note – Amniotic eggs are found in reptiles, birds, and mammals (NOT FISH)
Main stages of embryo development in humans
Fertilization -> zygote -> morula(4d) -> blastocyst(5-7d) (called blastula in other animals) -> gastrula(8-10d) -> embryo(8 wks) -> fetus(9wks-birth)
17. Who was Carolus Linnaeus? What does taxonomy means?
- Carolus Linnaeus is scientist who attempted to make order of all the various names that were given to animals by creating a unified system of taxonomy. His system used binomial nomenclature and used comparative anatomy.
- Taxonomy: The classification of organisms in an ordered system that indicates natural relationships
18. What is the order of organisms in taxonomy?
- Kingdom > phylum > class > order > family > genus > species
- (King Paul Came Over For Good Sex)
19. What are the rules of scientific name?
- First word is genus with a capitol letter; second word is species in lower case.
- Names must italicized or underlined (must be underlined if hand written). [Gorilla gorilla]
- Can use first initial of genus if the full name has been written previously in the same paper [G. gorilla]
- Subspecies (strains) may contain three names [Trypansoma bruccei rhodensiense, Trypansoma bruccei gamiense], writing the name as Trypansoma sp. references all subspecies.
20. What did Robert Whitteker proposed?
Robert Whitteker proposed that prokaryotic cells evolved into protista, and different protista involved into animals, plants, and fungi. This was proposed because various protista have characteristics of plants, animals, or fungi.
21. What is the classification of human?
- Kingdom: animalia
- Phylum: chordata
- Class: mamalia
- Order: primate
- Family: hominidae
- Genus: homo
- Species: sapiens
22. Why protozoa are animal like?
Most have no cell wall, many are motile in some way, and many ingest their food (heterotrophic)
23. Why protozoa are NOT animal like? And why they are plant like?
Some have cell wall, some are sessile (non-moving), some can perform photosynthesis (autotrophic)
24. What are the main characteristics of protista?
- Microscopic (for the most part)
- No germ layers
- Have specialized organelles
- Various forms are free living (live independently of other species), while others are symbiotic (two organisms that live together and one metabolically depends on another). Types of symbiosis in order of evolution with examples are listed below…
- Parasitism: one organism is benefitted while the other is harmed (eg. Malaria (Plasmodium) which can kill the human host)
- Commensalism: one organism is benefitted while the other is not harmed (eg. Entamoeba gingivalis in the mouth takes some of the food we eat)
- Mutualism: both organisms benefit from the relationship (eg. Trichonmypha in the termite gut have cellulase and can break down wood to glucose for itself and the termite)
- Some are sessile while others have pseudopodia, flagella, and cilia
- Some are autotrophic while others are heterotrophic
- Some are aquatic and some are terrestrial
- Some are asexual and some perform sexual reproduction
25. What are the organelles that protista might have?
- They contain most of the organelles that other eukaryotic cells posses
- Mitochondria: provides ATP
- Endoplasmic reticulum: protein synthesis
- Golgi Apparatus: packages/sends material
- Vesicles: transports items within a cell
- Chloroplast: photosynthesis
- Vacuoles: storage (waste, water, nutrients)
- Ectoplasm & endoplasm: function in organismal movement
26. What are different modes of locomotion in protista, explain each of them?
- Cilia and Flagella: contain 9 + 2 order of microtubules. Flagella is typically longer than cilia, with fewer found together (1000s of cilia).
- Pseudopodia: ectoplasm (transparent/hyaline outer layer) extends in the desired direction, and is followed by endoplasm (granular inner layer).
- Note – cytoplasm resides within the cell as normal, there is no membrane between ectoplasm and ectoplasm.
- Gliding: cell membrane rotates over microtubules under cell membrane like a tank.
27. What are different modes of osmoregulation in protista explain each one of them?
- Osmoregulation: Protista’s ability to regulate the amount of water within itself. Because a protista has more solute than its surroundings it is receiving a constant water flow, if left unchecked this would causes lysis.
- By contractile vacuole: (non ciliated) water is collected into vesicles, the vesicles dumb their contents into a contractile vacuole, then the contractile vacuole merges with the cell membrane to expel its contents outside the cell (exocytosis).
- In ciliates: Water from the endoplasmic reticulum (found throughout protista) is collected into one of many ampulla (which surround a contractile vacuole) then transferred to the contractile vacuole. One ampulla (the excretory pore) is attached to the cell membrane, and squeezes the water from the contractile vacuole out of the cell.
28. What are different modes of nutrition in protista?
- Autotrophs: self-feeding
- Heterotrophs: must ingest food
- Phagocytosis – cell eating
- Lysosomes – filled with enzymes to breakdown molecules
- Food vacuole – store food
- Exocytosis of the waste material after digestion
- Cilia have cytoproct (solid waste excretion area) for expulsion of solid waste
- Pinocytosis: cell drinking
29. Explain fission and different types of fission?
- Fission: asexual cell multiplication process when more individuals are produced
- Binary fission: two identical individuals are produced
- Budding: progeny is smaller than adult (usually ciliated organisms). A small part of the adult “pinches off” and becomes progeny
- [Multiple fission] Sporogony: development of spores or sporozoites within oocyst (usually 8 cells)
- [Multiple fission] Schizogony: when cytokinesis is preceded by several nuclear divisions. After schizogony some cells become macro/microgametes
30. Explain each different types of sexual reproduction in protista?
- Syngamy: fertilization of an individual gamete by another
- Isogametes: both gametes are equal size
- Anisogametes: both gametes are unequal size
- Autogamy: gametic nuclei fuse to form zygote within the same organism that produced them
- Conjugation: exchange of gametic nuclei (nuclear material) between paired organisms (protista come together, exchange, separate, then perform binary fission)
31. What is encystment and excystment and explain their importance?
- Encystment: during harsh (unsurvivable) conditions protista form a cyst around themselves. Multiplication stops, metabolism slows down, and the organism forms a thick wall.
- Excystment: After a favorable environment is restored they return to their normal state and begin to flourish.
32. What are major phyla of Protozoa? Give basic characteristics and examples of members?
- Euglenozoa: Some species with light sensitive stigma, chloroplasts, some parasitic, all examples are flagellated (Euglena, Trypanosoma, Leishmania)
- Dinoflagellata: amoebas even though they don’t have flagella, ceratium perform photosynthesis and have flagella (amoebas, foraminiferans, ceratium, Naegleria fowleri)
- Chlorophyta: perform photosynthesis, flagellated (Chlamydomonas, volvox)
- Retortamonada: Lack golgi body and mitochondria (Giardia)
- Axostylata: Large golgi bodies (Dientamoeba, Trichomonoas Vaginalis, Trichonympha)
- Apicomplexa: All parasitic, apical complex, asexual AND sexual cycle, some require intermediate host, most develop oocyst, class Coccidea contains most human parasites, locomotion via gliding (cell membrane moves over microtubules like a tank), may have pseudopodia in intracellular stages, flagella in gametes of some species (Babesia, Cryptosporidium, Eimeria, Isospora, Toxoplasma gondii, Plasmodium)
- Ciliophora: mostly freeliving, some parasitic, some commensalism, some colonial, some sessile, larger than most protozoan, multinucleated (micro and macro), undulating membrane, two contractile vacuole system (Balandtidium coli, Paramecium)
33. What are all of the examples of each phylum of protozoa + all scientific names of each genus?
- Euglenozoa: Euglena, Trypanosoma brucei rhodensiense, Trypanosoma brucei gambiense, Trypanosoma brucei brucei, Leishmania
- Dinoflagellata: Entamoeba histolytica, Entamoeba coli, Entamoeba gingivalis, foraminiferans, radiolarians, heliozoans, Ceratium, Naegleria fowleri
- Chlorophyta: Chlamydomonas, Volvox
- Retortamonada: Giardia intestinalis, Giardia lamblia
- Axostylata: Dientamoeba, Trichomonoas vaginalis, Trichonympha
- Apicomplexa: Babesia bigemina, Cryptosporidium parvum, Eimeria tenella, Isospora, Toxoplasma gondii, Plasmodium falciparum)
- Ciliophora: Balandtidium coli, Paramecium
34. What are the structures of Euglena? Reproduction method? Physical description? Other information?
- Pellicle: Protein and cell membrane material outside of the organism
- Kinetosome: DNA material at base of phlagellum
- Contractile vacuole
- Stigma: to locate light for photosynthesis
- Chloroplast: for photosynthesis
- Paramylon bodies: (starch deposits) storage area for glucose after synthesis
- Locomotion: flagella
- Reproduce by binary fission.
- Looks like a paramecium (football shaped), but MUCH smaller
- Free living, form cyst
35. Why are Volvox so special? Give all information about Volvox possible.
- Volvox are believed to be the stepping stone of evolution for multicellular organisms, due their colonization (division of labor between volvox). Vegetative cells perform photosynthesis.
- Have a cell wall, flagellated (2 flagella) not ciliated, multicellular, doesn’t cause harm
- They perform both sexual and asexual reproduction…
- Sexual: Some cells on mother colony differentiate into sperm/egg, sperm fertilizes the egg (autogamy), and form a zygote. The zygote multiplies and becomes a daughter colony. [Macrogametes loaded with food, microgametes form sperm to find the ovum]
- Asexual: a daughter colony can leave the mother colony and become a mother colony and form daughter colonies of its own.
36. What is pathology & life cycle of Trypanosoma? Give all information about Trypanosoma possible.
- Phylum Euglenozoa, parasites, flagellated, asexual reproduction (binary fission), do not cyst, located in blood (not feces or urine).
- Trypanosoma brucei Causes African sleeping sickness: parasite invades the brain causing temporary nervous system shutdown (sleep) or death. Transmitted by tsetse fly (Glossina) in an indirect lifecycle (must be transmitted by fly, not human to human). Found in Africa and parts of Asia. Animals in Africa can act as a reservoir for Trypanosoma brucei.
- Trypanosoma brucei rhodensiense: most dangerous to humans, can result in death
- Trypanosoma brucei gambiense: less virulent, usually causes sleeping
- Trypanosoma brucei brucei: found only in animals
- Trypansoma cruzi causes Chagas’ disease: causes heart problems, death can occur. Transmitted by kissing bug (Triatominae). Found in South America, Central America, and some parts of southern US.
37. What is pathology & life cycle of Leishmania ? Give all information about Leishmania possible.
- Phylum Euglenozoa, flagellated,
- Visceral Leishmaniasis: enlargement of liver/spleen
- Cutaneous Leishmaniasis: many bumps on the skin (“The Thing”)
- Both are transmitted by sand fly
38. What is the life cycle of Giardia and the disease they cause? Give all information about Giardia possible.
- Phylum Retortamonada, lack Golgi body and mitochondria, causes diarrhea, but doesn’t kill unless host is immunocompromised, can infect any animal, form cysts, flagellated trophozoites.
- Trophozoite look like pear-shape with two nuclei (looks like two big eyes), cyst stage has 4 nuclei.
- 2 types of Giardia: Giardia intestinalis and Giardia Lamblia
- Life cycle: Trophozoites (feeding stage) - in large intestine; multiply asexually by binary fission, feeding on epithelial cells in intestine causing diarrhea. Diagnostic/infective stage - resistant, infective cysts passed in feces (trophozoites may be found, but will not survive external environment). Method of infection – person ingests infective cysts (transmitted by feces) fingers, food, fomites, and biological vectors. Cyst passes to small intestine; excystment occurs and cycle repeats.
Give all information about Chlamydomonas, Dientamoeba, Trichonympha, Balantidium coli
- Chlamydomonas:Phylum chlorophyta. Photosynthetic. Astronauts take them for O2 production in space, because they cannot take that many O2 canisters.
- Dientamoeba: Phylum axosytlata
- Trichonympha: Phylum axostylata. Mutualistic symbiosis in termite gut (heterotrophic)
- Balantidium coli: Phylum Ciliophora. Reproduce with autogamy. Parasitic. Ciliated organism. Can be found in both human and pig.
39. What is Trichomonas vaginalis? Give all information about Trichomonas vaginalis possible.
Phylum Axostylata, parasitic, flagellated, STD, causes vaginitis, treatable, found in both males and females, direct lifecycle (human to human).
40. What are some of the amoeba? Give all information possible.
- Phylum Dinoflagellata (even though they don’t have flagella)
- Entamoeba histolytica: causes amoebic dysentery (diarrhea + blood), can cause death in children/immunocompromised in 3rd world countries
- Entamoeba coli: does not cause much damage in humans
- Entamoeba gingivalis: found in the mouth, have commensalism with host by living from food in mouth but not harming host. Can cause gingivitis if mouth hygiene is not maintained.
- Foraminiferans: shelled amoeba, made up of calcium carbonate, silica, and silt
- Heliozoans and Radiolarians subcategories of foraminieferans w/ shells primarily of silicon
- Naegleria Fowleri: devastating amoeba that will kill host in 5-7 days. Causes Primary amoebic meningoencephalitis (PAM) which results in inflammation of the brain. Usually found in autopsy due to lack of detection in small time-frame. Intravenous amphotericin B and miconazole plus rifampin stop N. Fowleri, but are typically not given due to lack of detection. Infection occurs by ingesting dirty water.
- N. Fowleri have 3 forms. Cyst form occurs during encystment in undesirable conditions, and transformation between flagellated and amoeba trophozoite stages occurs in the environment (warm water). Binary fission and transmission occur in amoeboid form.
- N. Fowleri are actually free-living in the water, but when we ingest them they “go berserk” and become highly parasitic killing their host and themselves in the process.
Direct vs indirect lifecycle
- Direct life cycle: No biological vector needed, can pass from species1 to species1 to species1
- Indirect life cycle: Biological vector needed to pass infection.
- Definitive host is site of sexual reproduction, Intermediate host is site of asexual reproduction.
41. What is apical complex?
The apical complex is an organelle found in phylum Apicomplexa which allows entry into a host cell. It consists of two parts (Rhoptries and Microenemes) which release molecules which temporarily dissolve a portion of the cell membrane so that the parasites can enter. (remember, all apicomlexa are parasitic).
42. What are the devastating Apicomplexa? Give all information possible.
- Class Coccidea contains many parasites that cause serious diseases in humans (Babesia bigemina, Cryptosporidium parvum, Eimeria tenella, Isospora, Toxoplasma gondii, Plasmodium)
- All parasitic, contain apical complex, asexual and sexual cycle, some require intermediate host, most develop oocyst, direct and indirect life cycles, locomotion via gliding (cell membrane moves over microtubules like a tank).
- Babesia bigemina: Causes Texas red-water ever in cattle (blood in urine)
- Cryptosporidium: devastating parasite, causes severe diarrhea, must go to hospital due to dehydration. Can kill immunocompromised. 2-4μm (cannot be filtered). Live in small intestine and respiratory epithelium. Direct life cycle. Microgametes and macrogametes. Oocyst in soil or water or air born. Outbreaks in D.C. and Milwaukee (public water infected with cow poop). Definitive AND intermediate host is human.
- Eimeria and Isospora cause coccidiosis
- Isospora: issue for immunocompromised (AIDS) patients, similar to Giardia.
- Eimeria tenella: is devastating in young chickens (all chickens in a farm dead overnight). Direct lifecycle.
- Reproduction of E. tenella: Ingestion of oocyst (containing 8 sporozoites) -> sporozoites release into intestine and reproduce (binary fission) (now called merozoites) -> schizogony occurs in intestinal epithelial tissue -> some merozoites differentiate into microgametes and macrogametes -> fertilization occurs and forms an oocyst -> oocyst is released into environment through feces -> sporogony in oocyst occurs in environment (8 sporozoites now in oocyst) -> new host ingests sporulated oocyst
- Toxoplasma gondii: dangerous to immunocompromised and fetus of pregnant woman, definitive host is cat (final host, sexual reproduction occurs), many possible intermediate hosts (human, dog, bird, cow, pig, etc). Life cycle can be direct (cat -> cat) OR indirect (meat -> human), does not appear in feces except cat feces. ((Much more detail in other questions))
- Plasmodium: 4 types, P. falciparim is most deadly to humans. Causes malaria, and is transmitted by mosquitoes. Indirect lifecycle (intermediate host is human, definitive host is Anopheles mosquito)
- P. falciparum within humans: sporozoites injected into human by mosquitoes -> sporozoites in liver initiate schizogony in hepatocytes (one generation only) -> penetrate RBC for remainder of existence (trophozoites feed on hemoglobin) -> some merozoites differentiate into microgametes and macrogametes in blood
- P. falciparum sexual reproduction: microgametes and macrogametes are circulating in blood and are ingested by mosquitoes -> Fertilization and creation of oocyst occurs in the mosquito gut -> sporogony occurs -> go to salivary gland of mosquito -> injected into another human
43. What is difference between oocyst and cyst?
- Oocyst is result of fertilization between microgamete and macrogamete (sexual reproduction)
- Cyst is protective state that many asexual protists undergo
44. What is the difference between life cycle of Plasmodium and Eimeria?
- Eimeria: direct life cycle, sporogony in environment, schizogony in chicken gut, prevention by separating feces from chicks
- Plasmodium: indirect life cycle (definitive host is Anopheles mosquito, intermediate host: humans or reservoirs), sporogony in mosquito gut, schizogony in human liver, RBCs, prevention with netting, masks, etc,
45. Explain the life cycle of Toxoplasma gondii?
- Cat is definitive host (sexual reproduction can only occur in cat). Intermediate hosts can be any number of animals including humans, goats, mice, pigs, cows, etc. Oocyst can stay in environment for months.
- Cat releases oocyst in feces -> takes 1-4 days for sporogony to occur -> host ingests oocyst -> host creates bradyzoites -> animal is eaten -> that creature is now the new host.
- Transmission can occur congenitally (mother -> fetus), through carnivorism (eating infected animal), or through oral ingestion of sporozoite (airborn, accidental touch, biological vector, etc)
46. What are the health hazards of Toxoplasma gondii?
- After initial excystment in intestines (will occur in any animal that ingests oocyst) you will have flu-like symptoms for about a week then no more symptoms although you will have T. gondii for life. Undergoes tachyzoite -> bradyzoite transitions throughout your life time, will continue this cycle unless you are immunocompromised. Immunocompromised hosts will not be able to control the tachyzoites stage and will die.
- Retardation, spontaneous abortion, and hydrocephalism can occur if a pregnant woman contracts T. gondii while pregnant (having the parasite before will not be an issue during pregnancy).
- Chorioretinitis: T. gondii can travel to the eye and cause blindness
- Pyrimethamine (a drug) can be used to slow down (cannot eliminate) T. gondii
- Note – cats contract T. gondii for life, but only release in oocysts in feces for first 21-30 days of infection.
47. What are the characteristics of Ciliophora?
- Mostly freeliving, some parasitic, some commensalism, and some colonial. Some sessile (eg suctorians). Larger than most protozoan, multinucleated (macronucleus for metabolism and micronucleus for reproduction), undulating membrane (cilia are fused into a sheet; also in Trypanosoma and Trichomonas Vaginalis), cytostomes (mouth), oral groove, two contractile vacuole system.
- Passage of water and food in paramecium: oral groove -> cytostome -> cytopharynx -> food vacuole -> indigestible solids out by cytoproct
- Reproduction by binary fission (micronucleus divide mitotically and macronucleus elongates and divides amotitoically), conjugation (exchange of genetic material then binary fission), and autogamy (self fertilization eg Balantidium coli)
48. How is conjugation done in ciliates?
- Meiosis occurs for macronuclei in both cells (creating 4 micronuclei and 1 macronucleus per cell) -> 3 micronuclei and the macronucleus disappears from both protista -> Mitosis occurs for the remaining micronucleus -> autogamy occurs (1 stationary nucleus and 1 exchange nuclei, exchange nuclei fuses with stationary nuclei from other protista and forms zygote) -> macronuclei return -> cells separate and perform binary fission.
- Performed to increase genetic variation for species sustainability (natural selection).