Microbiology 1 Study Guide

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Biology 2020 Microbiology
Study Guide for first exam

The history and scope of microbiology
1) What are the organisms/entities of study in the field of microbiology? * Bacteria
* Archaea
* Eukarya
* Viruses and Prions (Acellular entities)
2) Who was the first human to publish extensive descriptions of microorganisms? * Antony van Leeuwenhoek
3) How did Louis Pasteur dismantle the theory of spontaneous generation in bacteria? * Swan neck flask experiment: Flask with open top contained bacterial growth, while the swan neck flask caught the bacteria and the broth had no growth. 4) Who established microorganisms as the causative agent of infectious disease? How did he do this? What was the result of this body of work? * Robert Koch

* Studied Bacillus anthracis
* Took diseased mouse with anthrax and infected healthy mouse. This healthy mouse got sick. He then removed the spleens from the sick mice and isolated the anthrax spore. He injected that into healthy mice and they got sick. * Koch’s Postulates:

* Microorganism must be present in every case of disease * The organism must be grown in pure culture from the organism * The same disease must be reproduced when the pure culture affects another host * The microorganism must be recovered from experimentally infected hosts 5) What are some of the advancements that were made possible once microorganisms were identified as the causative agents of infectious disease. * Vaccinations: Weakened strains used to prevent original disease * Better public hygiene

* Sewages disposal practices
* Pasteurization
* Antiseptics
6) What are some of the future challenges in battling microorganism? Why are some of these challenges emerging? * Mutations and unique strains
* Jumping of species of diseases
* Antibiotic Resistances
* Emerging because of poor agricultural practices, animal migration, species jump, lack of vaccinations

The methods of microbiology
1) If you are viewing a specimen though a 60X objective lens on a compound microscope, what is the likely total magnification? * 60x * 10x = 600x
2) What type of lens does a microscope use to produce a magnified image? How does a lens produce a magnified image? * Convex lens
* Light bends when it hits the lens
3) What are some ways to increase contrast in microscopy? * Use stains to achieve contrast between cells and the background * Heating slide
* Using chemicals to preserve dead cells
4) Define: simple stain, differential stain and special stain. * Simple stain – Basic: stains the cell, Acidic: stains the background * Differential stains – Distinguish between gram positive and gram negative by staining cell wall * Acid fast stain – harsh stain that penetrates wax of mycobacteria by means of an acidified alcohol * Special stains - Stains specific parts of bacterial cell 5) What are the steps in a gram stain?

* Use crystal violet to stain all purple
* Use iodine to set stain
* Decolorize gram negative with acetone-alcohol
* Use safranin to stain gram negative red/pink
6) In general, can viruses be imaged with a light microscope? * No, an Electron Microscope is needed
7) Are all bacteria microscopic (beyond the ability to see with the naked eye)? * No, some can be seen without the use of a microscope

Prokaryotic structure and function
1) What are some of the shapes that bacteria exist as?
* Rods (bacilli), spheres (cocci), spirochetes (spiral), vibrio (kidney-shaped) 2) Are all bacteria of a single species the exact same shape? * No, pleomorphic bacteria can take more than one shape

3) What are some of the ways in which prokaryotic and eukaryotic cells are different? * Eukaryotes have a nucleus, true chromosomes, and organelles; Prokaryotes do not * Prokaryotes have peptidoglycan, eukaryotes do not

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