Lecture 2 Microscopy Cell Morphology Flashcards
What are the two types of cells?
Prokaryotic, eukaryotic
What is an example of prokaryotic cells?
Bacteria
archaea
What is an example of eukaryotic cells?
Eukarya
Which cell is larger?
Eukaryotic
Which cell is smaller?
Prokaryotic
What is eukaryotic cells defined by?
Presence of a nucleus
What is light microscopes magnification?
1,000x
What is electron microscopes magnification?
more than 100,000x
Scanning probe microscope can produce images of what?
Individual atoms on a surface
What are the three concepts of a bright field microscope?
Magnification, resolution, contrast
What is resolution?
Ability to distinguish two objects that are very close together
What are the two lens types in a compound microscope?
Objective and ocular
What are the magnifications of objective lenses?
4x, 10x, 40x, 100x
What is the magnification of the ocular lens?
10x
What does the condenser lens do?
focuses light on specimen
Which lens does not magnify?
Condenser lens
What is maximum resolving power of the light microscope?
0.2 micrometers
What is the point of the immersion oil on the 100x objective?
Prevents refraction of light, keeps rays from missing openings in objective lens
What do stains do in contrast?
They increase contrast but kill microbes
Electron microscopes use _______ lenses
_______
and _______ screen to replace glass lenses
Electromagnetic lenses
electrons
fluorescent
Resolving power of electron microscope
1,000 or greater
TOTAL power = 100,000x
In an electron microscope, lenses and specimen must be in _______
vacuum
Two types of electron microscopes
Transmission Electron Microscope TEM
Scanning Electron Microscope SEM
TEM is beam of electrons that pass ________ specimen or scatters
Through
TEM depends on the ________ of the region
________ is used to view internal details
density
thin-sectioning
what microscopy is a newer method that reduces damage to cells and creates 3-D images
Cry-electron microscopy
SEM is beam of electrons that scans ________ of specimen
Surface
in SEM, electrons are ________ from specimen
Released
What is a drop of liquid specimen that is overlaid with a coverslip?
Wet mount
What is simple staining?
uses a single dye to stain specimen
in a simple stain, what carries the positive charge? what carries the negative charge?
Basic dyes
acidic dyes
What are methylene blue and crystal violet?
basic dyes
An acidic dye can be done as a ________ ________
wet mount
What is differential staining
used to distinguish different groups of bacteria
What do gram positive and negative distinguish?
difference in cell wall structure
Steps of gram staining
- crystal violet (primary stain)
- iodine (mordant)
- alcohol (decolonizers)
- Safranin (counterstain)
In what step will gram + cells remain purple and gram - cells become colorless?
step 3 (alcohol)
What happens to cells in step 3 of gram stian?
gram positive: purple
Gram negative: clear
What happens in step 4 of gram stain?
gram positive: purple
gram negative: turns pink
What does the success of a gram stain depend on?
The length of time of the decolorizing step (step 3) and the age of culture
What is the acid fast stain?
used to detect organisms that do NOT readily take up dyes
What does acid fast stain detect?
Mycobacterium species such as causative agents of tuberculosis and Hansen’s disease (leprosy)
What do the cell walls of mycobacterium contain?
High concentrations of mycolic acids
Procedure of the acid fast stain
- Primary stain is concentrated red dye
- Acid fast cells retain red dye after being flooded with acid alcohol
- Methylene blue used as COUNTERSTAIN
What is the capsule stain?
Allows observation of gel-like layer that surrounds some microbes
What is stained in capsule staining?
The background
What is added to the wet mount in capsule stain?
India ink
What is endospore stain?
Allows visualization of endospores, resistant dormant cells often formed by Bacillus and Clostridium
What do endospores resist?
Gram stain, appears as clear object
Endospores stain use what to facilitate the uptake of the primary dye
Heat
What is the primary stain of endospore stain
Malachite green
What does the counterstain color in endospore stain?
Colors other cells pink that aren’t endospores
What is the counterstain of endospore stain?
Safranin
What is the flagella stain?
uses a substance that makes the dye adhere to thin flagella, making them visible
What is peritrichous cell?
Flagella surrounds the cell
What is polar cell?
Flagellum on one end
immunofluorescence uses what to tag a unique microbe protein?
Fluorescent dye-antibody labels
What shape is coccus
Spherical
What shape is rod?
Cyclindrical
Rod is also called
Bacillus
What is short rods called
Coccobacillus
Where is great diversity found?
in low nutrient environments
list other shapes from least curly to most curly
Vibrio (bent shape)
Spirillum (3 curls)
Spirochete (very curly)