Marb 435 1st Edition Lecture 4 Outline of Current Lecture Information about Metazoansand terms to know Current Lecture Metazoans Animal Cell Labeled Key for identification below picture B A I C J D K L E A B C D E F G H I J K M Microfilaments Flagellum F Nucleus Mitochondrion G Lysosome Chromatin H Nucleolus Microbody Golgi Terms to know Centrioles Smooth endoplasmic These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best reticulum L Ribosomes used as a supplement to your own notes not as a substitute M Microtubules N Rough endoplasmic reticulum O Cell membrane N O 1 Microfilaments molecules arranged in a helix and are made of actin 2 Microtubules hollow cylindrical structures with subunits that are heterodimers of atubulin and B tubulin 3 Cilia short structures with oar like motion 4 Flagella long structures with whip like undulation 5 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 or planktonic Metazoa 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 tissues Two 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 cells 3 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 to the blastula 8 Gastrulation process during which the germ layers are formed 9 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 pole 12 Holoblastic the entire zygote divides 13 Meroblastic only a specific region of the zygotes surface undergoes cleavage 14 Equal cleavage all cells resulting from early cell divisions blastomores are equal in size 15 Unequal cleavage blastomeres are unequal size macromeres and micromeres