MBB 231 Lecture Notes - Lecture 4: Methylene Blue, Cell Nucleus, Eosin

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4 Jun 2015

School

Simon Fraser University

Department

Molec Biol & Biochem

Course

MBB 231

Professor

Ingrid Northwood

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Document Summary

Lecture 4: microscopy - visualizing cells & molecules. All microscopes require 3 main elements for the formation of an image: a source of illumination, a specimen to be examined, a system of lenses to focus the illumination on the specimen. A microscope functions in detecting, magnifying, and resolving small objects. Magnification: enlarges an image, but cannot distinguish between 2 specific points. Resolution: the minimum distance that can separate 2 points. Increasing the resolving power allows for two points that are in close distance to one another to become. Visible: as wavelength decreases, the resolution increases. 2: angular aperture: the half angle (a) of the cone of light entering the objective lens from the. Specimen: angular aperture is a measure of how much of the light that leaves the specimen can pass through the lens. The higher the aperture the more light can pass through (maximum angular aperture = 70o): as the angular aperture increases, the resolution increases.

Related Questions

. On a given microscope, the numerical apertures of the condenser and low power objective lenses are 1.25 and 0.25, respectively. You are supplied with a filter that selects a wavelength of 520nm.

a.) What is the limit of resolution on this microscope? Please be specific to how you came up with this answer, what formula did you use? b.) Will you be able to distinguish 2 points that are 300nm apart as being separate, or will they blur into one?

on the same microscope as in Question#5, the high dry objective lens has a numerical aperture of 0.85, what is the limit of resolution on this microscope, and will you be able to distinguish 2 points that are 300 nm apart as being separate, or will they blur into one? Explain answer.

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QUESTION 4

A substance that reacts the same to light polarized in any direction is _________________.

	a.	an isotope
	b.	anisotropic
	c.	isotropic
	d.	divergent

QUESTION 5

The part of the comparison microscope that allows the examiner to view two objects simultaneously is called the _________________.

	a.	comparator
	b.	comparison bridge
	c.	spectroscope
	d.	stage

QUESTION 6

A stereo microscope can best be described as _____________________.

	a.	Two compound microscopes aligned so that they each see a slightly different part of an object.
	b.	Two compound microscopes aligned with a comparison bridge.
	c.	A compound microscope with two separate stages and one ocular.
	d.	A compound microscope with two eyepieces and a camera mount.

QUESTION 7

In microscopy, resolution is a measure of ________________.

	a.	The ability of the lenses to separate two tiny details that are close together.
	b.	The total magnification power of the microscope.
	c.	The empty magnification power of the microscope.
	d.	The ability of an electron microscope to determine the presence of a large number of elements.

QUESTION 8

Two polarizers (polarizing filters) aligned 90Â° from each other will block out all light.

True

False

QUESTION 9

A simple convex lens creates a magnified real image of an object.

True

False

QUESTION 10

A trinocular microscope has three objective lenses mounted on a turret.

True

False

QUESTION 11

Liquids and gases are usually isotropic.

True

False

QUESTION 12

Match each of the following terms with Its Definition

Compound microscope a. Has a polarizer and an analyzer

Electron microscope b. Permits viewing two objects at once

Stereomicroscope c. Consists of a single convex lens

Comparison microscope d. Long working distance, three-dimensional

Simple hand magnifier e. Basic 2 convex lens microscope

Polarizing microscope f. Can magnify images more than 100,000 times

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Expalin in detail each question and provide a concise answer.

1.You are assigned a microscope that is equipped with 5X, 10X, 20X, 40X objective lenses. Which one of these objective lenses should be used when you first examine a slide specimen under the microscope? Explain why this objective should be used.

2.How will working distance change as you progress from a low power objective to successively higher power objectives?

3. What causes the inversion of image that you observed through the compound

microscope? Which lens is responsible for this phenomenon?

How does the fieldof view change as you progress from a low power objective to successively higher power objectives?

How does the size of the iris diaphragm opening affect contrast? Consider both light colored samples and dark samples (i.e. a white nylon thread and a black hair).

How does the size of the iris diaphragm opening affect resolution? Would this be affected by the magnification used to observe the sample?

7. How does depth of field change as you progress from a low power objective to

successively higher power objectives?

MBB 231 Lecture Notes - Lecture 4: Methylene Blue, Cell Nucleus, Eosin

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