MICROBIOLEC Unit 2

What are 5 types of light microscopy

Bright field

Phase contrast

Dark field

Fluorescence

Confocal

Bright field microscope (2)

Dark image against bright background

Used for observing stain specimens

Dark field microscope (2)

Ideal for viewing live unstained specimen

Bright image against dark background

Phase contrast microscope (2)

Good for transparent specimens

Converts phase shifts in light passing through as brightness changes

Fluorescent microscope

Uses fluorochrome stains to visualize specimens that emit light under specific wavelengths

Confocal microscope

Uses a laser to scan specimens to eliminate out of focus light creating sharp 3D images

Resolution

Ability to distinguish between two different adjacent objects as separate

______ is used to increase resolution by ____ light refraction increasing aperture of lens

Oil immersion, decreasing

Importance of staining (3)

Enhances visibility

Accentuates features

Preserves specimens for observation

What are 2 fixation method

Chemical fixation

Heat fixation

Chemical fixation

Used for larger, delicate organisms to protect fine structures

Heat fixation (3)

Commonly used for bacteria and archaea

Preserves cell morphology

Distorts internal structure

Types of stain (4)

Basic staining

Acidic staining

Simple staining

Differential staining

Basic dyes

Positive charged binding to negative cell components like nucleic acids

Acidic Dyes

Opposite binding negative charge

Simple staining

Uses single dye to determine cell shape size and arrangement

Differential staining

Uses stains to differentiate between organisms

What are special staining techniques

Capsule stain

Flagella stain

Capsule staining (2)

Used for polysaccharide structures

Stains the background to visualize

Flagella stain

Adds a mordant that better visualizes the flagella

Advanced microscopy techniques (2)

Electron microscopy
Scanning probe microscopy

How to get total magnification

(Occular magnification) x (Objective magnification)

What is resolution, describe how its defined

The ability to distinguish two adjacent objects as separate of distinct, it is determined by light wavelength used and numerical aperture of lens

What is limit of resolution for light microscope

0.2 uM

What is microscopic contrast

Enhances the visual boundary between organisms and their backgrounds

What are two ways to achieve visual contrast

Chemical staining
Optical microscopy techniques

Refraction

Bending of light when passed through a medium

Degree of bending is determined by ______ of the medium

refraction index

Lens functionality

Lens focus light rays at a focal point, focal length inversely related to magnification power

Types of Electron Microscopy

Transmission electron microcope
Scanning electron microscope
Electron cryotomography

Transmission electron microscope (2)

Electrons are transmitted through the specimen
Creates detailed image of its internal structure

Scanning electron microscope (2)

Electrons are focused on the surface
Creates 3D surface image

Electron cryotomography (2)

Rapidly freezes specimens
Hi-res visualization of native cell structure and macromolecules

Scanning tunneling microscope (2)

Uses current to visualize cell surface at the atomic level
Creates a 3D topological map

Atomic force microscope

Measures microscopic physical forces between a sharp tip and the sample
Creates detailed image of surfaces at the molecular and atomic levels

Gram-negative bacteria appears _______ after staining

red

Gram-positive bacteria appears _______ after staining

purple

True or false. Viruses are classified as cells

False

True or False. Viruses have a metabolism

False

True or False. Viruses can infect all cells

True

Genome

Cell’s full complement of genes

During cell division, nucleus divides by _____

mitosis

During sexual reproduction, the genome is _____ by meiosis

halved

Evolution

Process of change across time that results in new traits and variety of new organisms

Phylogeny (2)

Evolutionary relationship of organisms

Relationship deduced by comparing different genetic information of different organisms

What are 3 domains

Archaea

Bacteria

Eukarya

Archaea is much more closely related to _____ than _____

eukarya, bacteria

Chemoorganotrophs (3)

Energy derived from oxidation of organic molecules

Aerobes use oxygen to obtain energy

Anaerobes obtain energy w/o energy

Chemolithotrophs (2)

Obtain energy from inorganic molecules

Present only in prokaryotes

Phototrophs (3)

Uses light as energy source

Oxygenic photosynthesis produces oxygen

Anoxygenic photosynthesis does not

Autotrophs (2)

Use carbon dioxide as energy source

Also called as primary producers

Heterotrophs

Require one or more organic molecules for carbon source

Extremophile

Organisms capable of living in extreme conditions

All known _____ prokaryotes are ______

pathogenic, bacteria

_____ makes up the largest phylum of bacteria

Proteobacteria

Phyla of domain archaea

Euryarchaeota

Crenarcheota

Subclass of Euryarchaeota

Methanogen

Thermoacidophile

Extreme halophiles

Methanogens (2)

degrades organic matter anaerobically produces methane

Thermoacidophile

Resides in moderately thermal and low pH

Extreme Halophiles

Requires high salt concentration for metabolism and reproduction

Cyanobacteria is a relative of gram-_____ bacteria

positive

Characteristic of rRNA coding genes (4)

Universally distributed

Functionally constant

Highly conserved (slow change)

Adequate enough to provide deep vide of evolutionary relationships

_____ are a mutualistic relationship between two protists

Lichens

Give 2 example of lichens

Fungi & cyanobacteria

Fungi & algae

What is application of light microscopy

Suitable for general observation of specimen, live cells and basic structure

What is application of electron microscopy (2)

Ideal for high resolution imaging of cellular structure and viruses
Enables detailed study of ultrastructure

What is application of scanning probe microscopy

Minimal preparation
Allows observation of cells in native state

Practical applications of microbiology (3)

Medical microbiology
Environmental microbiology
Molecular biology