VCU BIOL 209 - Final Exam Study Guide (5 pages)

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Final Exam Study Guide

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Final Exam Study Guide


A more general study guide for the 30 question, cummulative final exam

Study Guide
Virginia Commonwealth University
Biol 209 - Medical Microbiology
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BIOL 209 1st Edition Final Exam Study Guide What are the different methods used to identify specific microorganisms Polymerase Chain Reaction PCR assay based on DNA sequences unique to a particular microbe ELISA assay uses antibodies to detect structures unique to a particular microbe Informal classification used if microbe has not developed reagents uses cell shape dye staining properties metabolic properties and growth requirements unique to a particular microbe What are the differences in envelope structure that distinguish Gram positive and Gramnegative bacteria Gram positive bacteria firmicutes contain teichoic acid and lipoteichoic acid with a thick cell wall peptidoglycan layer surrounding an inner cell membrane Gram negative bacteria proteobacterials contain porin proteins lipoproteins and lipopolysaccharides with a thin cell wall peptidoglycan layer sandwiched between an inner and outer cell membrane List 3 extracellular appendages and describe their function Flagella provide mobility and in some cases adhesion Conjugation pili are long protein fibers that mediate the initial attachment of conjugating bacteria which allows the transfer of DNA from one bacterium to another Fimbrae are relatively short protein fibers that contribute to adherence to inanimate surfaces other microorganisms and select host tissues Biofilms are complex communities of microbes that adhere to a surface and each other through the production of a very thick and sticky slime layer Compare a slime layer and a capsule list their similarities and differences A slime layer consists of loosely associated glycocalyx which helps retain water and nutrients A capsule is a thicker glycocalyx associated closely with the envelope It can provide protection by blocking phagocytosis by host immune cells What are the characteristics of a biofilm What advantage does a cell gain by living in it A biofilm is complex dynamic and sticky A cell that lives on biofilm becomes highly resistant to physical and chemical treatments including many host immune mechanisms Compare and contrast endospores and cysts bacterial and eukaryotic flagella biofilms and hyphae Endospores are more durable than cysts but both protect bacteria from harm Some forms of cysts and spores can survive higher temperatures for a limited time Both spores and cysts can lay dormant for long periods of time Bacterial flagella are smaller and simpler in structure made up of protein flagellin move in rotation and are proton driven Eukaryotic flagella are larger and complex in structure made up of tubulin bend to move and are ATP driven Biofilms are made up of multiple species Hyphae are made up of one single species Both function in adhesion and protection are multicellular and obtain food by absorbing nutrients Name the different classes of Protozoans Compare protozoans to fungi how are they similar How are they different Ciliates flagellates sporozoans and amoebas are the four classes of Protozoa Fungi are multicellular while protozoa are unicellular Fungi invade tissues and digest material externally by digesting enzymes What are the basic classes of viruses What are the components of virus structure and what are their functions The basic classes of viruses are enveloped naked and complex They consist of nucleocapsid proteins and specific enzymes necessary for replication Viruses attack a host cell s functions and utilize them for their own benefits Viruses control host cells function to promote viral genome replication and viral protein production In what ways are viral genomes diverse What determines which cells viruses infect How do viruses enter cells Viral genomes are either DNA or RNA and can be either single or double stranded Their structure is usually circular or linear or otherwise packaged as separate segments Size varies but they are relatively small A host cell s specific surface receptors must match that of a virus for the virus to infect it Enveloped viruses enter cells through either fusion or endocytosis Naked viruses enter cells through endocytosis only Bacteriophages bind to specific receptors on the cell enevelope and directly inject their genome into the host cell Why do cells have receptors for viruses Trick question Cells have receptor proteins designed to do a specific job and the virus borrows the receptor for its own benefit What is viral latency Some viruses have the option of persisting in a host cell hanging out for a while without killing it but reactivate later on This is referred to as viral latency How do bacteria grow What determines their growth rate What are the phases of their growth What are the conditions affecting their growth Bacteria grow exponentially Their growth rate is determined by nutrient availability The four phases of growth include the lag phase which consists of adjusting metabolism the exponential phase which is the maximum growth rate the stationary phase consisting of depleted nutrients increased toxic products and reduced cell size and finally death where more cells are dying than dividing The conditions effecting growth include changes in pH temperature salt concentration and oxygen availability Describe the different ways that a microbe may adapt to changing growth conditions 1 Conjugation genetic transmission through direct contact a plasmid or fragment of DNA is transferred from a donor to a recipient cell through direct connection Gram and gram bacteria can conjugate but only gram s can operate with a specialized plasmid fertility F factor Both the donor and recipient have to be alive Bridge forms between cell surfaces to interact with pilus to transfer plasmid or just DNA in general Rarely is the entire genome transferred just a portion usually High frequency transfer the donor cell retains one strand of DNA and the other strand is transported to the recipient in a higher frequency than other cells Biomedical importance R plasmids factors bear genes resistant to antibiotics and other drugs and are shared by bacteria through conjugation 2 Transformation capturing free DNA from solution nonspecific indirect acceptance of small fragments of soluble DNA from the surrounding environment Griffith s experiment with rats live non virulent cells picked up loose DNA from dead mice who carried dead virulent cells that had broken open so they too became virulent DNA even from a dead cell retains its genetic code Chromosomes released by lysed cells break into fragments small enough to be picked up by

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