Study Guides (380,000)
CA (150,000)
Western (10,000)
BIOL (1,000)

Biology 2382B Study Guide - Midterm Guide: Antonie Van Leeuwenhoek, Hat Medium, Green Fluorescent Protein

Course Code
BIOL 2382B
Sashko Damjanovski
Study Guide

This preview shows pages 1-3. to view the full 14 pages of the document.
Central research strategy in cell biology, which implies observing cells and cell
organelles as well as visualizing cellular and molecular processes, such as gene
expression and protein interactions, various cellular repossess, monitoring of cell
trafficking and targeting, and detecting individual molecules in cells.
Historically, imaging using light microscopy has been a key tool for biologists
from the outset - indeed, cell biology was literally born with microscopy.
Seminal observations of Robert Hooke under the microscope (Micrographia,
1665) led to the initial coining of the term "cell" (referring to a tiny bare room,
similar to a monk's cell).
Since then, microscopy has revolutionized our understanding of how cells live
and die. New subcellular compartments have been discovered thanks to
improving microscopy techniques, and progress in cell biology sill relies in great
part on advances in imaging technique
Built many simple, single lens microscopes
First to observe living protozoa and bacteria which he called "animalcules"
Went on to visualize human red blood cells and sperm
With great skill at grinding lenses, naturally acute eyesight and lots of patience he
was able to achieve a magnification of 200X
Anton van Leeuwenhoek (1632-1723)
Overall magnification = ocular lens x objective lens
Light microscope is using regular white light from a light bulb (often focused
into the specimen).
Important: the object must be opaque. You need to be able to bend light or
block light to be able to see it.
Compound microscope: microscope using more than one lens
Features of a Modern Compound Microscope
Resolution: the ability to distinguish between two very closely positioned
objects as separate entitles.
A conventional microscope can never resolve objects/cellular features that are
Resolution of Microscopes
Section 2: Imaging in Cell Bio
Tuesday, January 12, 2016
6:18 PM
Midterm 1 Page 1

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

A conventional microscope can never resolve objects/cellular features that are
less than ~02uM apart
Smaller resolution the better (means you can distinguish between things that are
very close together)
Ideally you want something that is bigger than one so an oil drop is placed so that
light doesn't have to travel through air. You get a better resolution because the
refraction index is higher.
A high N value and A value are key. A is the amount of light that is getting to the
lens. The problem is that if you want a wide lens you have to grind it perfectly.
Wavelength Spectrum Used in Microscopy
Obtaining contrast in light microscopy by exploring changes in the phase
of light.
Midterm 1 Page 2

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Certain parts of the cell (i.e. nucleus) refract light more than other parts
Cellular constituents with high refractive properties can slow the passage of a
light beam by a quarter fraction.
When it shifts you are changing the pattern of light.
When some light passes through it changes the pattern (out of phase) due
to interference.
As light is passing through the sample it can sift by almost a quarter.
You can manipulate this and make your cell eve darker to
increase contrast.
The shift makes it darker.
Some cells are darker vs lighter because of the interference.
Specimen has to block light or refract light.
Phase Contrast Microscopy
The microscope has a specific set up: annular diaphragm and a face plate.
No sample = light goes through annual diaphragm (see a hazy grey of scattered
Sample = blocked light. Sample causes the ring of light to shift.
One way its shifted is up to a quarter of a wave length.
Midterm 1 Page 3
You're Reading a Preview

Unlock to view full version