Unit 1 Exam Study Guide

Microbiology

study of small organisms

Romans

created sewer system to deal with waste

Hippocrates

Father of Western Medicine (diseases were not caused by supernatural)

Thucydides

Father of scientific history
(Early concept of immunity)

Marcus Terentius Varro

Proposed that things we cannot see could cause disease

Leeuwenhoek

Father of microbiology (used magnifying lens to observe "animalcules" in rain drop

Louis Pasteur

Fermentation and spoilage caused by microbes; pasteurization, vaccination

Robert Koch

Established method for connecting pathogen with specific disease; created Koch's postulates

Carolus Linnaeus

Categorized Plants and Animals

Ernst Haeckel

Proposed four kingdoms of Animals, Protists, Plants, and Monera

Robert Whittaker

Add Fifth Kingdom of Fungi

Woese and Fox

Established 3 Domains of Bacteria, Archaea, and Eukarya (small subunit ribosomal RNA sequences)

Microbial Classification

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species, Strain

Binomial Nomenclature

Two word system that names organisms based on genus and species (Genus is capitalized, species is lower case; all words italics) (ex. H. sapiens)

Bergeu's Manual for Determinative Bacteriology

guide for identifying microbes on various methods for non-visual characteristics.

Archaea

-Different evolutionary history, genetics, metabolism, physiology from bacteria
-Pseudopeptidoglycan
- Extreme environments

Algae

- Unicellular eukaryotes
- Photosynthetic, important in ecosystems and consumer products

Protozoa

-Unicellular eukaryotes
- Very diverse; motility, flagella, pseudopod

Fungi

-Multicellular and Unicellular
- Chitin cell walls
- MOLDS; good & bad

Helminths

-Multicellular parasitic worms
-Microscopic eggs and larvae

Viruses

-Acellular
- Require a host to reproduce

Prions

proteinaceous disease causing agent

Wavelength

length between peaks

Amplitude

height of peaks

Frequency

rate of peaks in time

Relationship between wavelength and frequency

Longer wavelength \= lower frequency

Reflection

wave bounces off material

Absorbance

wave is captured

Transmission

wave travels through

Interference

interacts w/ another wave

Diffraction

bent or scattered by object opening

Refraction

change direction and/or speed

Refractive Index

Degree of change in transmission speed

T/F statement of refraction

If light enters a substance with a higher refractive index it slows down and bends toward the normal line (away from the boundary)

Convex lens refraction

occurs on a curved boundary to meet a focal point (microscope)

Concave lens refraction

lights away from a focal point (flashlight)

Electromagnetic Radiation Spectrum

- Higher frequency waves have higher energy
- Certain materials can refract non-visible into visible

Magnification

ability of a lens to enlarge the image of an object

Contrast

creation of stark difference in coloration

Resolution

ability to tell that two separate points/objects are separate

Factors that affect resolution

- Wavelengths (shorter wavelengths \= higher resolution)
- Numerical Aperture (ability to gather light by lens)

Who utilized the 1st simple microscope?

Leeuwenhoek

Galilei

used a compound microscope

Robert Hooke

first to describe "cells" using compound microscope and observing cork cells

Hans and Zacharias Janssen

simple and compound microscope

Microscope Types

Light, electron, scanning

Total Magnification

Ocular x Objective

Path of Light

Illuminator, condenser, specimen, objective lens, ocular lens

Darkfield Microscopy

-Brightfield w/ modified condenser
- Light that is viewed through objective lens is reflected/refracted from specimen

Phase Contrast Microscopes

- Increases contrast w/o stains
- Good for viewing live specimens and organelles
- Features are highlight based on refractive index

Differential Interference Contrast Microscopes

-Two different wavelengths are passed thru specimen and combined for differential effects.

Fluorescent Microscope

-used to absorb and refract into visible light
- Direct & indirect

Confocal Microscopes

- Scans multiple z-planes
- Thick specimens
- Modified fluorescence to avoid "bleaching"

Two-Photon Microscope

- Good for viewing thicker material
- Modified confocal scope with near infrared light
- Minimizes light scattering through tissue

Recall

Resolution is limited by wavelength

Electron microscopes

use electrons and have short wavelengths

Types of electron microscopes

Transmission Electron Microscope & Scanning Electron Microscope

Transmission Electron Microscope

- Forms image based on varying opacity of specimen
- Specimens are cut very thin

Scanning Electron Microscope

-Electrons are bounced off specimen w/ coating
- Surfaces are easily observed

Scanning Probe Microscopy

-Atomic scale microscopy
- Viruses and smaller

Wet Mount

good for viewing live specimens

Fixed mount (smear)

good for staining

Basic Stain

- positive charged ions
(Basic fuchsin, Crystal Violet, Malachite Green, Safranin, Methylene blue)

Acidic Stain

- Negatively charged ions
(Eosin, rose Bengal, acid fuschin)

Positive stain

Dye/Stain absorbed into cells

Negative Stain

Dye/Stain absorbed into background

Simple stain

- Emphasizes Structure
- Single Stain

Differential stains

- Differentiates organisms based on stain interactions
- 2+ stains

Gram Stain

- Distinguishes different cell wall components
- Important clinical diagnostic tool

Steps for Gram Staining

1. Primary stain (crystal violet) 2. Mordant (iodine) 3. Decolorizer (alcohol) 4. counter stain (safranin)

Acid Fast Stain

- Diagnostic tool for detection of mycolic acid and Mycobacterium spp.

Ziehl-Neelson method

w/ heat

Kinyoung method

w/o heat

Capsule strain

- Diagnostic tool for detection of protective coating
- Dyes do not penetrate capsule
Steps are no heart smear and Primary stain (India ink)
- Positive and negative staining techniques to visualize capsule

Endospore Stain

- Identification of endospore formers
- Schaeffer Fulton method
Steps (Heat fix smear, primary stain (malachite green), Decolorizer (water), Counter stain (safranin) ).

Flagella Stain

- Identification of flagella appendages
- Bacteria, archaea, eukaryotes
(No heat smear, Primary stain (specialized), Decolorizer (water), Counter stain (carbol fuschin) ).

TEM

- Samples analyzed must be very thin (ultramicrotome)
- Specimen embedded in plastic resin and dehydrated
- Stained with electron dense heavy metals

SEM

- More dehydrated - critical point drying with liquid CO2
- Sputter-coated with metal

Ancient belief

Life can arise from nonliving matter

Franceso Redi

False for spontaneous generation
(meat and maggot container)

John Needham

True for spontaneous generation
- Broth was boiled

Lazzaro Spallanzani

False for spontaneous generation
- Replicated Redi & Needman Experiments

Louis Pasteur with Spontaneous Generation

Swan Neck Experiment
- False

Modern Cell Theory

All living organisms are composed of one or more cells
- Cell is basic unit of structure
- All cells come from existing cells

Matthias Schleiden

plant tissue

Theodor Schwann

compared plant and animal cells

Robert Remak

cells come from other cells

Rudolf Virchow

published "Cellular pathology" (all cells arise from cells)

Konstantin Mereschkowski

chloroplasts could reproduce independently and must have lived outside plant cell

Ivan Wallin

showed mitochondria outside of cell (but was prob contamination)

Lynn Margulist

-used DNA, fossil, biochem, organelle etc. evidence to support theory

Endosymbiotic Theory

Mitochondria and Chloroplasts were originally prokaryotic cells that established a symbiosis within a eukaryotic host.

Girolamo Fracastoro

"spores" can be transferred between individuals

Ignaz Semmelweis

- "Contaminated" physicians transferred causative agent to patients
- Promoted handwashing as solution

John Snow

Cholera outbreaks in London traced to sewage in drinking water

Louis Pasteur w/ Germ Theory of Disease

Organisms could spoil food and therefore people

Joseph Lister

handwashing + carbolic acid in surgery for disinfection

Robert Koch w/ Germ Theory of Disease

Koch's postulates \= a specific microbe can cause a specific disease

Elements of the Generic Cell

Cytoplasm, Plasma Membrane, Chromosome, Ribosome

Unique Elements of the Prokaryotic Cell

Nucleoid, Inclusions, Plasmids, Pili, Fimbriae, Endospore