Lecture 3 - Microscopes Flashcards
Who coined the term “cell”?
Robert Hooke
The unaided eye can see things larger than ___ mircometers.
200 micrometers
1 millimeter =
1/1000 of a meter
1 micrometer =
1/1,000,000 of a meter
1 nanometer =
1/1,000,000,000 of a meter
Size of Red Blood Cells (RBCs)
5 micrometers
What type of microscope is used to view viruses?
Electron Microscope
Typical Size of a Virus
100 nm
Typical Eukaryotic Cell Size
10 micrometers
Typical Size of Prokaryotic Cell
1 micrometer
Diameter of DNA Double Helix
~2 nanometers
Which two Domains of Life are Prokaryotes?
Bacteria & Archaea
Simple Light Microscope
uses only one lens to magnify specimen
Compound Light Microscope
uses 2 or more lenses to magnify specimen
Ocular vs. Objective Lenses
Ocular Lenses are the ones you look through with your eyes (#eyepiece) and the Objective Lenses are the lenses closest to the specimen being viewed.
Who developed the first compound light microscope in 1595?
Zacharias Jansen
Who Developed the first simple microscope in 1670?
Antony van Leeuwenhoek
Illuminator
the light source
diaphram on a microscope
controls how much light is allowed to reach the condenser below the specimen
What role does the lens inside of the condneser of a microscope play?
it focuses the light that will shine up through the specimen
Stage
where the specimen to be viewed is placed
At which two points on a compound microscope is a specimen being magnified?
Maginified at the Objective & Ocular Lenses
What is the standard magnification of the Ocular Lens on a compound microscope?
10x
How to Determine the Total Magnification
multiply the magnification of the ocular lens by the magnification of the objective lens
Ocular Lens x Objective Lens
Name the 4 Standard Objective Lenses on a Compound Microscope and Their Magnifications
Scanning Lens 4x
Low Power Lens 10x
High Power Lens 40x
Oil Immersion Lens 100x
Which Lens on a Compound Microscope is the Shortest?
Scanning Lens
(4x magnification)
Which Lens on a Compound Microscope is the Longest?
Oil Immersion Lens
(100x magnification)
Resolving Power/Resolution
sharp/clear image
how far apart two adjacent points can be from each other and still be seen as two distinct points
Refractive Index
how much the light waves bend when passing through a medium
Easiest Way to Change the Refractive Index of a Specimen
Staining
The refractive index of Immersion Oil is the same as ______.
Glass
Brightfield Microscopy
The background behind the specimen is bright.
Darkfield Microscopy
an opaque disk blocks some of the light from entering the condenser.
Specimen is seen on a dark bakground
Phase Contrast Microscopy
The background appears dark; Internal organelles are seen clearly and easily see cell surface features such as cilia.
Compare & Contrast Darkfield Miscroscopy vs Phase-Contrast Microscopy
Both have dark backgrounds, but organelles can be viewed easier with phase-contrast microscopy. Phase-contrast is also more expensive to use.
Two Types of Phase-Contrast Microscopy
Positive and Negative
Positive vs Negative Phase-Contrast Microscopy
Postive: the specimen appears darker than the background; lighter halos can also be seen around the specimen
Negative: the specimen shows up bright against the background.
DIC
Differential Interference Contrast Microscope