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Marb 435 1st Edition Lecture 4Outline of Current Lecture Information about Metazoansand terms to knowCurrent Lecture: MetazoansAnimal Cell Labeled. Key for identification below pictureTerms to know:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. A. MicrofilamentsB. FlagellumC. NucleusD. MitochondrionE. LysosomeF. ChromatinG. NucleolusH. MicrobodyI. GolgiJ. CentriolesK. Smooth endoplasmic reticulumL. RibosomesM. MicrotubulesN. Rough endoplasmic reticulumO. Cell membraneACDEFGHBIJKLMNO1. Microfilaments – molecules arranged in a helix and are made of actin.2. Microtubules- hollow cylindrical structures with subunits that are heterodimers of a-tubulin and B-tubulin.3. Cilia- short structures with oar-like motion.4. Flagella- long structures with whip-like undulation5. Protists- unicellular eukaryotic organisms that were once considered one of the five kingdoms but is now considered polyphyletic.6. Protozoans- subset of protists that lack collagen and chitinous cell walls. They can be very complex even though they are unicellular.7. Choanoflagellata- the sister group to metazoans. They are small organisms that have a long flagellum surrounded by a circle of microvilli.8. Ciliophora- protozoan group that is partially or completely covered with cilia. They contain and micronucleus and macronucleus and use simple forms of sexual reproduction.9. Dinoflagellata- protozoan group that usually have two flagella, can have solid tests, and include species that can cause harmful algal blooms (red tides)10. Foraminifera- protozoan group that are benthic or planktonic organisms that have multichambered calcareous tests. They are used to date sediment layers because they are well preserved in the fossil record.11. Radiolaria- protozoan group that has spherical, siliceous tests. They are either benthic orplanktonicMetazoa Multicellular organisms commonly known as animals Protozoa (= early animals) were originally considered animals too, but are now considered a polyphyletic assemblage Metazoa evolved from protozoan ancestors Metazoan cells are generally organized in tissuesTwo basic types of tissue are:Epithelial tissue - layer of adjoining cells covering the body or lining an internal cavity; cells secrete abasal lamina and are connected by intercellular junctions.Connective tissue – widely separated cells embedded in an extracellular matrix (ECM)Epithelia are mostly absent in sponges (phylum Porifera) and in Placozoa.The Extracellular Matrix is a network of polysaccharides and proteins (e.g. collagen), secreted by cells. It provides structural support of tissues and plays an important role in development and physiology of cells and tissues.Even More Terms to Know!1. Collagen- fibrous proteins that only metazoans have. It is a major component of skin and bone and consists of a triple-helix of polypeptide chains.2. Gapjunctions- allow exchange of small intracellular signaling molecules. It directly connects the cytoplasm of adjacent cells3. Beltjunctions- (also known adherence junctions or tight junctions) are barriers to diffuse membrane proteins and lipids and it forms a seal between neighboring cells.4. Desmosomes- dense plaques of protein functioning as anchors for intermediate filaments in cells.5. Colonial Theory- the theory that metazoa was derived from a colony of flagellated protozoa.6. Syncytial Theory-the theory that metazoa evolved from a multinucleate but unicellular syncytium. (cell with multiple nuclei)7. Cleavage- rapid sequence of cell divisions without growth, leading from the zygote tothe blastula.8. Gastrulation- process during which the germ layers are formed9. Germ layers- tissues from which all later organs develop (ectoderm, endoderm and mesoderm)10. Animal pole- zygote surface that the nucleus is closest to.11. Vegetal pole- opposite side to the animal pole12. Holoblastic- the entire zygote divides13. Meroblastic- only a specific region of the zygotes surface undergoes cleavage14. Equal cleavage- all cells resulting from early cell divisions (blastomores) are equal in size15. Unequal cleavage- blastomeres are unequal size (macromeres and


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