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Penn State - MICRB 201 - Microbiology Exam 2 - Study Guide

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Schools > Pennsylvania State University > Microbiology > MICRB 201 > Penn State - MICRB 201 - Microbiology Exam 2 - Study Guide

Penn State - MICRB 201 - Microbiology Exam 2 - Study Guide

School: Pennsylvania State University
Department: Microbiology
Course: Introductory Microbiology
Professor: Olanrewaju Sodeinde
Term: Fall 2016
Tags: Viruses, Ecology, historyofmicrobes, Bacteria, and evolution
Name: Microbiology Exam 2
Description: This study guide is specific to the material covered in lecture.
Uploaded: 03/10/2018
This preview shows pages 1 - 2 of a 6 page document. to view the rest of the content
background image Exam 2 Study Guide MICRB 201  Viruses  ❖ Genetic element (DNA, RNA)  ➢ Cannot replicate independently  
➢ Needs host cell 
❖ Virion - extracellular shape of virus (different from viroid) 
❖ Chamberlain filter - has the ability to filter out all known bacteria (1884) 
❖ Ivanovsky - filterable agent reinfects tobacco plant (1892) 
➢ Early definition of virus - can it pass through a Chamberlain filter?  ❖ d'Herelle - uses bacteriophages to treat bacterial infections (1919)  ➢ Bacteriophages discovered by Twort, but he ignored them because he’s stupid  (bacteriophages tworted him) (not a word)  ❖ Oncoviruses  ➢ Olaf and Ellerman: Chicken Leukemia (1908) 
➢ Peyton Rous: Rous Sarcoma Virus (1910) 
➢ Led to discovery of oncogenes 
❖ Ruska-Knoll Microscope - first view of viruses (1931) 
❖ Lysis vs.lysogeny 
❖ Bacteriophage λ adsorbs to LamB protein on E.coli 
➢ Lacks genes for ribosomes, means of self-replication  ❖ Lysis Pathway  ➢ Adsorption to recognized proteins 
➢ Insertion of genetic material 
➢ Synthesis of nucleic acids and proteins 
➢ Assembly of new viruses 
➢ Lysis - cell explodes and new viruses are released 
■ Burst size = # virus per cell 
■ Enveloped viruses do not lyse, they bud 
❖ Lysogenic Pathway   ➢ Adsorption to recognized proteins 
➢ Insertion of genetic material 
➢ Integration of viral DNA/RNA into host genome 
■ Prophage - part of virus DNA that is in the host genome 
■ Lysogen - cell that has viral DNA in it 
➢ Replication   ❖ Capsid - protein shell  ➢ Capsomere - proteins that make up the capsid in a repetitive manner 
➢ Smallest part of a virion that can be seen with a microscope 
background image ❖ Nucleocapsid - combination of the capsid and the genetic material 
❖ Shapes 
➢ Rod/helical symmetry - genome determines length, size/packaging of  capsomeres determines widths  ➢ Icosahedral symmetry - most efficient packaging of capsomeres 
➢ Complex - icosahedral head and helical tail 
❖ Classified by type of genetic material  ➢ dsDNA vs ssDNA: double stranded vs single stranded 
➢ dsRNA vs ssRNA: same deal 
➢ Retrovirus: ssDNA to dsDNA; reverse transcription 
❖ Very high mutation rates, small genome 
❖ Viroids, ssRNA, sDNA have the highest 
❖ Allows them to evolutionize and to escape the immune system 
❖ Bacteriophages, archaeal, plant, animal viruses 
❖ Titer - number of infectious material per liquid unit 
➢ Plaque starts in a single cell, reproduces, spreads in circular formation 
➢ Latent period - creation of subunits and whatnot 
■ Eclipse: early enzymes, nucleic acids, protein shells 
■ Maturation: assembly and release 
❖ # of virions/volume > # of pFu/volume    Animal viruses  ❖ Sandwich animal cells between gel medium after virus liquid had been washed away  ➢ Cells will lyse 
➢ Virion ENTERS the cell, not adsorps to it 
❖ More enveloped animal viruses than bacterial enveloped viruses  ➢ Persistent infections - slow release of viruses without causing lysis (HIV) 
➢ Transformation - formation of tumor 
➢ Latent infections - slower transition between infection and lysis (Herpes) 
❖ Viroid - causes disease in plants  ➢ Complementary 
➢ Creates a rolling process of RNA synthesis 
❖ Prion - infectious proteins  ➢ Discovered by Pruisner (1997) 
➢ Occurs randomly, inherited mutation, and by inoculation 
  Evolution  ❖ Change of species over time 

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School: Pennsylvania State University
Department: Microbiology
Course: Introductory Microbiology
Professor: Olanrewaju Sodeinde
Term: Fall 2016
Tags: Viruses, Ecology, historyofmicrobes, Bacteria, and evolution
Name: Microbiology Exam 2
Description: This study guide is specific to the material covered in lecture.
Uploaded: 03/10/2018
6 Pages 56 Views 44 Unlocks
  • Better Grades Guarantee
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  • Notes, Study Guides, Flashcards + More!
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