Lecture%204 - Biology 301 Infectious Disease & Society...

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Unformatted text preview: Biology 301 Infectious Disease & Society Course Days: Friday Course Time: 1:30pm 4:10pm Instructor: Nathan Dougan Review: Viruses The important characteristics 1. 2. 3. Viruses are composed of nucleic acids (genetic material) that can be either DNA or RNA. These nucleic acid (genomes) are surrounded by a protein coat (capsid) Some viruses will have an membranous envelop (often host-cell phospholipid bilayer, but can have other molecules) Review: Viruses 4. Viruses can only reproduce within a host cell (they lack the metabolic machinery to reproduce independently). 5. Viruses utilize a variety of reproductive mechanisms within host cells that may or may not kill the host. 6. Some viruses may remain "latent" in host cells until a metabolic opportunity stimulates disease-causing activity. Review: Viruses Review: Viruses Review: Viruses How do viruses cause disease? Like bacteria must adhere to and colonize a tissue, viruses must first attach to a host cell and then gain entry. Capsid or envelope proteins/glycoproteins are the keys in attachment and also in invasion. Remember that a virus must get inside the host cell in order to survive. Review: Viruses Once inside a host cell, viruses utilize the host's metabolic machinery to make copies of the viral genome and then ship that genome out of the cell to infect more host cells. Sometimes, this process kills the host cell and sometimes the host cell may survive. Review: Viruses Like bacteria, viruses often infect only a specific range of host cells (host range). Some viruses are very specific, while others may some variability in their targets (ex. Swine influenza, rabies). Review: Viruses Important Lysis Concepts & Terms: / Lytic Cycle Cycle Lysogenic Pathogenic Protozoa What are Protozoa? Protozoa are unicellular eukaryotes, (singular protozoan). While there is no exact definition of the term, most scientists use protozoan to refer to a unicellular heterotrophic protist, like amoebas and ciliates. The term algae is used for the photosynthetic microorganisms. However, the distinction between the two is often vague. For example the alga Dinobryon has chloroplasts for photosynthesis but it can also feed on organic matter and is motile http://en.wikipedia.org/wiki/Protozoa Pathogenic Protozoa "a phylum or subkingdom of chiefly motile unicellular protists (as amebas, trypanosomes, sporozoans, and paramecia) that consist of a protoplasmic body either naked or enclosed in an outer covering, that have holophytic, saprophytic, or holozoic modes of nourishment, that reproduce asexually by nuclear division usually with a more or less modified mitosis associated with cytoplasmic binary fission or with multiple fission or budding or often sexually by various means, that have the life cycle simple (as in an ameba) or extremely complex (as in many sporozoans), that are represented in almost every kind of habitat, and that include pathogenic parasites of humans and domestic animals". http://medical.merriam-webster.com/cgi-bin/medical Pathogenic Protozoa Protozoan (singular)- A protist that lives primarily by ingesting food, an animal-like mode of nutrition. (Campbell 1999) Protozoa single-celled eukaryotes that do no have a rigid cell wall. (Salyers 2002) Pathogenic Protozoa 1. 2. 3. Very helpful reference sites: http://www.ourfood.com/Parasites_Pathogen http://www.albany.edu/sph/coned/lesson6.pd http:// www.microbiologybytes.com/introduction/Par Protozoa vs. Bacteria Eukaryotes Membrane-bound Prokaryotes No nucleus and organelles May membrane-bound nucleus or organelles reproduce sexually or asexually (binary fission) Reproduce only asexually via binary fission. How do Protozoa cause disease? Protozoa, like bacteria, are simply trying to survive and multiply. Their pathology is similarly resultant from colonization features, immune system evasion techniques, and hypersensitive reactions. Unlike bacteria, protozoa tend to have non-infectious forms as the result of a particular life-cycle stage (oocyst). Protozoa of interest Cryptosporidiosis Cryptosporidium parvum Amebiasis Entamoeba histolytica Giardiasis Giardia intestinalis Malaria Plasmodium Helpful Animations http://www.sumanasinc.com/scienceinfocus/si http://www.idexx.com/animalhealth/testkits http://www.liquidjigsaw.com/animation/anim4.h /giardia_canine/giardiavideo.jsp http://www.biology.ualberta.ca/parasites/P arPub/update/animate.htm CDC Guide to parasitic protozoans http://www.dpd.cdc.gov/dpdx/Default.htm Malaria http:// www.sumanasinc.com/scienceinfocus/sif_mala www.sumanasinc.com/scienceinfocus/sif_mal Giardia http://www.idexx.com/animalhealth/testkits/gia ...
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This note was uploaded on 04/29/2009 for the course BIOL 301 taught by Professor Kocache,m during the Spring '08 term at George Mason.

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