Biol 242: Week 6 Notes (Exam 2)
Biol 242: Week 6 Notes (Exam 2) BIOL 242
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This 11 page Class Notes was uploaded by LaKeisha Crum on Friday September 30, 2016. The Class Notes belongs to BIOL 242 at University of Louisville taught by James Alexander in Fall 2016. Since its upload, it has received 36 views. For similar materials see Diversity of Life in Biology at University of Louisville.
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Date Created: 09/30/16
Fungi : * Crash Course video over fungi basics: https://www.youtube.com/watch? v=m4DUZhnNo4s Chytridiomycota (chytrids) ancestral group for fungi. Similar to slime molds and water molds. Retain flagellated cells at some stages in life cycle. Fungi basic information: Common characteristics: Lack chlorophyll, lack flagella (minus chytrids) because of cell walls, mostly unicellular, heterotrophic, saprophytic nutrient attainment. Vocab Review: saprophytic consumes dead, organic matter. Symbiotic absorbs liquids from living host. Nutrition: Absorption! They do this by being saprobes or symbionts. Some are parasites, mutualists, commensals. Haustoria: specialized hyphae that penetrate through plant cell walls to obtain nutrients. TIP: You can remember this by associating the word haustoria with hysteria (they sound the same). Just think, these specialized hyphae cause hysteria by tearing through the cell walls. Fungal Structure: Cell wall: strengthened by chitin, defends against bacteria. Mycelium: composed of hyphae. Hyphae: make up the mycelium, large number of filaments. Two types aseptate (no cross walls between cells and nuclei meaning multinucleated. septate (not multinucleated. Separated by porous cell wall) TIP: Septate sounds like separate so the cells are separated by walls. Life Cycle: Zygotic Alternates between haploid and diploid states. Diploid is brief. Steps: 1. Plasmogamy: fusion of hyphae and cytoplasm of two mating strains. 2. Dikaryotic Hyphae Forms: two cells containing two different haploid nuclei. TIP: we usually associate “karyotic” with cells. So just think “di”= 2, “karyotic”=cells. So two cells with two nuclei. 3. Karyogamy: fusion of two nuclei (+/). *This is our brief diploid stage* Meiosis quickly follows to give meiospores (haploid spores) 4. Meiospores are dispersed and then germinate produce hyphae. Hyphae that are a combination of two mating strands. The zygote (+/ fusion) Asexual Reproduction: aside from the above sexual steps, fungi also produce asexually. This occurs when the mitotic division of hyphae occurs to make asexual spores and conidiophores. These form hyphae that are basically genetic clones. Zygomycota : “algallike” (hence the green color). Live in both marine and fresh waters. Life Cycle: 1. Hyphae of two mating strands come in contact to produce extensions called gametangia. 2. The two fuse (plasmogamy) and create a unicellular zygosporangium. It has two haploid nuclei. 3. A rough, thickwalled coating is created to protect the zygosporangium for months. 4. Under favorable conditions, karogamy occurs (fusion of the two haploid nuclei). This forms a diploid nuclei. Meiosis quickly occurs. 5. The zygosporagnium opens and a sporangium grows on top of a stalk. Haploid spores are dispersed. 6. The spores germinate and produce the haploid hyphae. *Asexual reproduction can also occur. The mycelium forms spores in this phase that creates new hyphae. *Aseptate hyphae, septa found on bottom of gametangia. Ascomycota : “sac fungi” Either unicellular yeast (yellow color) or septa (hyphae with uninucleate cells containing crosswalls) Life Cycle: 1. Hyphae of two different mating strands come in contact and form extensions (gametangia) called ascogonia and antheridia (look familiar ?). 2. Plasmogamy occurs. 3. Many hyphae with the two nuclei form a cuplie structure called an ascocarp. At the end of this is an ascus. 4. Karyogamy occurs in the ascus to form the diploid nucleus. It then quickly undergoes meiosis. 5. These four nuclei undergo mitosis to make eight nuclei. 6. The ascospores are then released from the end of the ascus. 7. They land and germinate. TIP: Ascocarp just remember that “asco” goes with the Ascomycota and “carp” kind of looks lie cap. So you can just think a cap that holds ascospores inside. *Asexual the spores are formed externally at the end of the hyphae (called condiophores). They germinate as well. Basidiomycota : “club fungi”, Fungi referred to as mushrooms (hence the different colors mushrooms are different colors) and toadstools. Many are obligate parasites, some are wood decaying organisms (bracket fungi), some edible, others are poisonous, largest and oldest are in this group. Life Cycle: 1. Hyphae of two different mating strands comes into contact. 2. Plasmogamy occurs. 3. Dikaryotic mycelium is formed that is very large. 4. When the environment is favorable, the dikaryotic mycelium forms basidiocarps (very rapidly). The basidiocarps are the “mushrooms”. This lives for many years (opposed to the ascomycetes where this dikaryote is only found in stages before the ascocarp) 5. In the gills on the underside of the mushroom, there are swollen cells on the hyphae tips. Here the dikaryotic cells form basidia (clubshaped) 6. Karyogamy occurs in the basidia. Meiosis then quickly occurs. 7. These form a basidiospore. They break away and are carried to germinate. Basidium Fig.31.18 (Campbell’s Biology) Deuteromycota: (“Fungi Imperfecti”) molds (hence black and green color), sexual phase unknown, multicellular, rapidly growing, asexual, can produce zygosporangia, basidiocarps, and ascocarps, but sexual not known (imperfecti in name they’re not perfect like the others.) Examples: Penicillium (produce penicillin) and Aspergillus but were however moved in Ascomycetes because their sexual phases were discovered (once this is discovered, the species can be moved into the appropriate category) Yeasts : Unicellular fungi that are in aquatic environments. Uses: bread, wine, cheese, beer Examples: Candida can be passed sexually, live in moist mucous linings (vagina) can be problematic. Rhodotorula shower curtains – pinkish. Reproduction: asexual (budding) Lichens : Composite fungus (mycobiont) and alga (phycobiont). These two are dependent on each other. Phycobiont unicellular green alga or cyanobacterium. TIP: “Phy” reminds me of photosynthesis so I think green. Green leads me to think of green and cyanobacteria since they are blue/green. The fungus and alga live together in a relationship. The phycobiont completes photosynthesis. Cyanobacteria phycobionts can also fix nitrogen that the fungus can use. In return, the fungus protects the alga. This relationship helps them survive and grow in harsh areas where plants cannot. Reproduction: (asexually). They produce soredia few hyphae around the algal cells. Mycorrhizae : ReviewMycorrhizae is a relationship between roots and fungi. The fungi increase the surface area and absorption of minerals and H2O. In return the fungi gets sugar from the plant. Can sometimes be parasitic. Like lichens, a relationship is formed between two organisms. This time it is plant roots and fungi. Yeah, we’ve heard this before so here’s some new stuff. Fungi that create this: Zygomycota, Ascomycota, and Basidiomycota. TIP: It’s always good to make acronyms for content like this. The one that I made for this is ABZ (kind of like abs). It also helps to make funny or memorable associations. One for this section could be Lichens= I like those ABZ. So I “lich” those ABZ. Animals We are animals! So if you can remember what we do then you’ll be fine. We’re heterotrophs that need organic material and we ingest stuff right? Quick Review: we have no cell walls, collagen structural proteins that make up animal bodies, tight cell junctions Animal Tissues: Epithelial, Connective, Nervous, and Muscle TIP: Make an acronym that works for you. For example: CNEM (looks like CHEM), or MENC Gametic Life Cycle: Diploid adult stage, haploid gametes formed by meiosis. Adults form these haploid gametes that form with other adult gametes to form the zygote. Mitosis then occurs in the zygotes to form larval or juvenile stages. Life Cycle Cont… After the ova and sperm unite, mitotic division creates a solid ball of cells called the morula. The morula then forms the blastula. The blastula is a hollow ball of cells. The central, fluidfilled cavity inside the blastula is called the blastocoel. *Pay attention to the size & amount of cells. Gastrulation Cells move into the inside of the blastocoel. This creates an internal cavity called the archenteron (turns into the gut lining) Blastopore opening to the outside (turns into the anus or mouth, depending) Blastopore Archenteron Blastocoel After gastrulation, organogenesis begins. Organogenesis is when specific organs are created. TIP: Genesis means the origin or formation. The word means Organ formation. Finally, the animal can then develop into a mature adult or it may continue developing through more larval stages. The animal at this stage may be completely different from the adult and they are sexually immature. After this stage they will go through metamorphosis to complete their development. Body Plans: we can place animals in groups based on four qualities. These are body symmetry, the presence/absence of true tissues, diploblastic vs. triploblastic, and the germ layers. Body Symmetry Asymmetrical no axis, no symmetry, cannot be divided in any way. Ex. Sponges Radially can be divided in many ways through the central plane (topbottom). No separate head, no left/right. Mirror halves in many ways. Ex. Hydra. Radiata goes with cnidarians and ctenophores. These are called sessile because they must be prepared for their environment in all ways and directions. Bilateral (Bilateria) twoside symmetry, only one plane of division through the central axis that makes two equal sides (“bi” means 2.) These animals have distinct characteristics: lateral (distinct left/right), anterior (distinct head), posterior (distinct tail), dorsal (back or upper surface), and ventral (bottom surface). Diploblastic vs. Triploblastic: Diploblastic two germ layers in the animal. These two layers are the ectoderm (outer layer of cells of the gastrula) and the endoderm (inner layer of the cells that make up the archenteron). These end up composing the skin and gut lining. Triploblastic three germ layers. In these animals, a third layer is added to the other two. These cells are the mesoderm cells. They enter in the blastopore and form clusters near the archenteron. Germ Layers: Ectoderm give us the nervous system, tissues of the skin ( also includes hair, scales, enamel of teeth, inner ear, lens of the eye, nails) Endoderm: give us the gut lining, digestive organs, glands (liver and pancreas), lung epithelium but only in higher animals like us. Mesoderm: give us muscle cells, blood cells circulatory system, skeletal systems, reproductive organs, excretory systems, endocrine system, lining of body cavity (peritoneum) Body Cavities/Body Plans: There are 4 main types. They allow the room for organs to grow and they cushion the organs from physical damage, they increase the surface area for gas and nutrient movement, act as a hydrostatic skeleton, provide material storage, and are a way for waste and gametes to exit. Gastrovascular cavity these are fluid filled tracts in Cnidarians. These are incomplete systems (one opening that acts as the anus and mouth). These cavities can also be hydrostatic skeletons. These support the body and has fluid inside held under pressure. Acoelomate The difference in these animals is the presence of mesoderm tissues inside of the body cavity. They also have gastrovascular cavities. This body plan is found in the flatworms. Psudocoelom In these animals, a fluid filled cavity develops between the mesoderm and endoderm. We call these animals pseudocoelomates. This layer is only partially lined with mesodermal derived tissues. In the pseudocoelomates, the gut is not surrounded by muscles. Instead, the food passes through because of the contraction of the outer body wall muscles. This contraction puts pressure on the psudocoelom fluid. Coelom or eucoelom This type is only found in the most advanced animals. A body cavity forms in tissues during development. It is lined with mesodermal tissues. The digestive, circulatory, reproductive, and other organs are within the coelom double layers of tissues. These are called mesenteries. Protostomes: the blastopore becomes the mouth. The anus comes later. Animals: annelids, molluscs (dominant), arthropods and nematodes (sometimes in this group but don’t always develop exactly in this way) Deuterostomes: The anus forms from the blastopore and mouth forms later. Animals: echinoderms and chordates. TIP: “stome” means having a mouth or mouth like organ. “Proto” means first. Therefore the word protostome means first mouth. This will make this easier to remember. Cleavage Types: Spiral cell division is diagonal to the vertical axis of the embryo. (Protostomes) Radial cell division occurs at right angles to other planes. The cells stack on top of each other. Determinate the fate of each cell is determined early on. The blastomeres (early cells) five rise to different parts of the embryo. Single cell cannot be separated from the other cells or it will die. (Protostomes) Indeterminate the ability to create identical twins from one fertilized egg. The fate of the eggs are not determined until later on. Has the potential to develop into a separate organism if separated in the early stages. (Deuterostomes) Coelom Creation: Schizocoelom As the archenteron forms, mesoderm masses form near blastopore. Later on, these split open and form a fluid filled cavity. This is the schizocoelom. TIP: Schizocoelom starts with an s and so does split. (Protostomes) Enterocoeloms Masses of mesodermal cells “bud” off of the archenteron. This forms the enterocoelom. (Deuterostomes) Calcarea and Silicea: Sponges or Porifera Cellular level of organization. This means no organs or systems. For gas exchange, the sponges use diffusion. These cells are all independent and because of this, they can complete somatic regeneration. Somatic regeneration is the sponge’s ability to form a new sponge after cells in the original sponge were separated. This also relates to the fact that sponges are totipotent. This means that the cells in the sponge are capable of developing into any other cell type. Structure of a Sponge: Ostia these are the small pores that allow water to enter the sponge. Spongocoel the large middle opening in the sponge Osculum the larger pore at the top of the sponge. The water exits through this. Spicules what the internal skeleton is made of. These are either siliceous or calcium carbonate. Spongin network of proteinaceous fibers that are sometimes present in the spicules. Choanocytes: flagellated cell. These line the spongocoel. They have a collar of cytoplasm that catches the food particles that pass from the water in the sponge. From that point digestion occurs intracellularly. Pinacocytes: These make up the outer covering of the sponge. They look like plates. Amebocytes: these digest and transport the food that they get from the choanocytes. They can produce the spicule and spongin, control reproduction, and contract the sponge. Reproduction: Sexually: After fertilization, mitosis occurs that creates the larva. It is then released into the water. It floats around until it sticks to an area. Mitosis then continues to create a new adult sponge. ( Vocab Review: Monoecious these organisms have both male and female reproductive organs. TIP: One plant mono, both parts. ) Asexually They can also use budding and fragmentation to reproduce. (Gemmule a cluster of amebocytes in a hard shell. These can survive harsh conditions) Radiata: Cnidarian Common characteristics: Diploblastic and acoelomate body plan. The two dermal layers are: Epidermis (outer) and gastrodermis (inner). In between these layers is the mesoglea (noncellular gelatinous layer). This layer is thin in hydrozoans and thick in scyphozoans. Two body forms: Sessile polyp and freeswimming medusa. Cnidocytes stinging cells (especially on the epidermis). Nematocyst a cell inside of the cnidocyte. This is spiked, harpoon like cell that can be discharged out of the cell to attack intruders or food. They are threadlike and wrap around the target. TIP: “nema” means resembling a thread. Nerve net no distinct brain but a net that can identify stimuli. Digestion: extracellularly in gastrovascular cavity. They excrete digestive enzymes into this cavity. First, chemical digestion happens extracellularly, then the soupy broth of food is brought into the cell using endocytosis. The rest of digestion is completed in the food vacuoles. Reproduction Asexual: budding Sexual: either polyps or medusa produce sperm and egg. Fertilization occurs externally in the water. If the fertilization is internal then it occurs in the female. Major Classes: Hydrozoa both polyp and medusa stages. Polyp is dominant. Mostly marine. Scyphozoa true jellyfishes. All marine and medusa is dominant. Anthozoa All marine, no medusa stage, sessile polyps. Polyps can be individual or colonial. Bilateria Lophotrochozoa: these animals have bilateral symmetry. They are the Platyhelminthes, molluscs, and annelids. Ecdysozoa nematodes and arthropods Deuterostomia echinoderms and chordates Platyhelminthes flatworms Common characteristics: Osmoregulation/Excretory System: Contains protonephridia that have flame cells at the end. Flame cells are flagellated (flagella resembles a candle flicker. Hence their name). Body Plan: Triploblastic, acoelomate. Bilaterally symmetric. Cephalization: clusters of nerve cells (ganglia) in the anterior (head) end with nerve cords running posteriorly. Can learn. They have tissues and organs. (Epithelial, muscular, nervous tissues. Digestive, sensory, nervous, and reproductive organs) Incomplete digestive tract. Either extracellular digestion (chemical) or absorption through body wall. Movement: move with cilia. They secrete a thick mucus to make this possible. Undulation of body wall muscles. Reproduction: most monoecious and can selffertilize but others can cross fertilize as well. Asexual fragmentation and regeneration Major Classes: Tubellaria free living, predators or scavengers mostly but some are parasites, marine and freshwater, cilia to move Trematoda (flukes) Parasitic (live in the liver, lung, stomach, bladder of vertebrates), the vertebrate is the definitive host where sexual reproduction occurs. They exit the vertebrate by ripping through the cells and entering the feces. They then find an intermediate host (usually snail) to complete asexual reproduction. They exit through the stomach of the snail (Dr. Alexander used the movie Alien as an example). The cercaria is what exits the snail. It is a forked taillike larvae. They then enter the vertebrate again.
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