Microbiology Lab 1A

What is Parfocal

When the microscope is in focus at low magnification, it will remain, approximately in focus as you change to a higher magnification objective. Only minor adjustment of the fine knob should be required to bring the specimen into focus..

What type of light does a light microscope use to focus on a specimen

Visible light

What is visible light?

A form of electromagnetic radiation that travels in waves with wavelengths between 400nm and 750nm

Energy ______ as wavelength decreases

increases

which wavelength has more energy? Top or bottom

Bottom

Which types of electromagnetic radiation are more energetic than visible light?

Ultra violet rays, X-rays, gamma rays

Which types of EMR are less energetic than visible light?

Infrared light, microwaves, radio, and television rays

Name Each color in the spectrum of visible light

Red, orange, yellow, green, blue, indigo, violet.

Refraction

bending of light as it passes through one state of matter to another (gas, liquid, solid, plasma)

With the compound light microscope, light must pass through

glass to air and back again multiple times, being refracted each time before it reaches our eyes. 

Fill in the blank and answer the question :

The microscope has ____ objectives, each containing a ____ lens capable of what?

four objectives; biconvex lens; capable of magnifying a specimen to differing degrees and focusing light from that image on a single point

Immersion oil function

reduce/eliminate refraction of light and increase the resolution of light as it passes through the glass slide and into the glass 100x objective lens. 

Why can immersion oil reduce refraction when sliding the objective lens?

Since oil has the same refractive index as glass it allows the light to pass straight from the glass slide through the oil and into the glass high-power objective lens, rather than being bent as it passes from the glass slide through air to the glass 

If correctly focused at 10x, the objective lens should rotate directly into the drop of immersion oil. True or false

True

Which objective has the following traits?

• Lowest power for large microorganisms

• Not strong enough to view bacteria

• Used as a way to scan for large microorganisms via the coarse focus knob

• Used with lowest amount of light controlled by the condenser diaphram

• Shortest length objective lens and largest working distance

• Largest diameter lens

4x

Which objective has these traits?

• Lowest power for small microorganisms before moving to higher power

• Used to quickly scan large areas of interest on the slide

• used with the lowest amount of light

• With bacteria focused on this magnification before moving directly to 10x

10x

Which objective lens has these traits?

• Has moderate power and high dry lens

• Highest magnification used without immersion oil

• Used with the fine focus knob

• Used with a moderate amount of light

40x

Which objective lens has these traits?

• Highest power obective and must be used with immersion oil

• Used to fine focus on the smallest microorganisms

• Smallest diameter lens

• Is put into immersion oil

100x

What is Resolution

 The ability to distinguish between two very close objects

What is Field of View

the circular viewing area an organisms.

What does Paracentric mean?

organisms located in the center of the field of view at one magnification will remain in the center when using any other magnification objective.

When would you need more immersion oil?

When the field of view starts going in and out of focus

What is working distance?

The distance between the objective lens and the specimen

What is the function of the ocular lens

The lens you look through that provide an additional 10x magnification

Function of Coarse adjustment knob

Make large adjustments to focus microscope

Function of Fine Adjustment Knobs

Makes small adjustment to focus on organism

Function of the objective lens

Lens with different magnification ranging from 4x-100x that helps you see organism closer

What is the mechanical stage

where you put your slide

Function of condenser/condenser adjustment knob

Helps focus light onto specimen and located on the left side of the stage

Function of Iris Diaphragm

Adjusts amount of light passing through condenser. It controls depth of field, improves contrast, and maximises resolution

Function of mechanical stage control knob

A spring clip that allows you to move the slide left and right and up/down. 

What is the difference ebtween a compound light microscope and a microscope

A compound light microscope uses light to pass through a specimen and uses two lens to form an image while a simple microscope uses a single magnifying lens to produce an enlarged image.

What is the difference between bright field microscopy and dark field microscopy.

In bright field microscopy, the sample is above a condenser that shoots a light and the central beam isn’t blocked. In dark field microscopy, the central beam is blocked and leads to a dark background with a light sample

What is the difference between bright field microscopy, dark field microscopy, and phase contrast microscopy?

Phase contrast microscopy has a phase shifter above the objective lens which is used for thicker organisms and can increase contrast with light. Bright field has no phase shifter while dark field has a shifter below

What separates transmission electron microscopy from other forms of microscopy

It uses beams of electrons to interact with samples. Through this, it can look at viruses, blood cells, have a resolution of 0.2 and can magnify much higher than other microscopes

What separates fluorescent microscopy from other types of microscopy

sourceIt uses laser as a light sources, uses fluorescent dyes and stains, and can visualize autofluorescent cellular structure. Additionally, it’s light waves go through a different tradjectory

As magnification increases, which factors of a microscope decreases

Field of view, depth of field, working distance, light intensity

As magnification increases, these factors increase

resolution, Size of image, amount of light required, length of objective

which relationships are directly proportional to an increase in magnification

Length of objective, amount of light required, resolution

Which relationships are inversely proportional with an increase in magnification

working distance, depth of field, field of view

Which is the only objective lens that should come into contact with immersion oil

100x

How to calculate total magnification

objective lens x 10

why is immersion oil necessary to view very small organisms such as bacteria

to reduce the refraction of light that would happen

What does the term function mean?

What something does whether it being an organism, part, or a part of something bigger.

Which property of light is most important for microscopy?

refraction

Write the correct choice for each of the following statements:

As wavelength decreases/increases, energy increases.

As wavelength decreases/increases, energy decreases.

Shorter/longer wavelengths have higher energy.

Shorter/longer wavelengths have lower energy.

Therefore, wavelength and energy are directly/inversely proportional.

1. Decreases

2. Increase

3. Shorter

4. Longer

5. Inversely

Common units of measurement in microbiology include ‘mm’, ‘μm’, and ‘nm.’ These are abbreviations, what is the full term for each? 

nm=nanometer 

mm=millimeters 

µm=micrometers

1 millimeter equals how many micrometers?

1 micrometer equals how many nanometers

1 millimeter equals how many nanometers?

1 millimeter=1000 micrometers

1 micrometer=1000 nanometers

1 millimeter=1000000 nanometers

how do the common units of measurement relate to 1 meters

1 m= 10^-9 nanometers
1 m = 1000 millimeters 

1m= 1000000 micrometers

Which is the most energetic color in the visible lght spectrum? Least energetic?

Most energetic is violet. Least energetic is red.

Why does a ‘red’ sweater look red when it is seen in visible white light, which contains all of the colors of the spectrum?

It’s absorbing all the other colors and reflects red.

What does the term ‘mnemonic’ mean? Give an example

A way letters are arranged to aid in recalling information. Example is ROY G GIV

What does X mean in 10x or 100x oil

The magnification

Other than magnification, what is different about the ‘100X Oil’ objective lens from the other objective lenses

It’s the only one that uses oil and has the highest resolution. It uses the most amount of light. This is what is needed for it to be able to see the most smallest microorganisms or prokaryotes.

What is a scientific protocol? 

a detailed, written plan for conducting a scientific experiment or study

What does the index of refraction/refractive index measure?

a measure of how light refracts through a material or The speed of light in another material.

What important parts, located under the stage, are not shown in this figure? Hint: One is a lens and the other controls the amount of light passing through the lens and onto the specimen.

Condenser (latter) and iris diagram (former) 

iris diaphram controls amount of light passing. Condenser controls the amount of light passing through the lens and onto the spcimen.

What is the type of relationship between magnification and the amount of light passing through the specimen?

Inverse proportional

Why is the total magnification 400x when using a 40x objective

Because of the ocular. lens, there is a 10x increase to an objective.

Name Every piece of the microscope

A. Eyepiece

B. Observation Tube

C. Neck

D. Coaxial Stage controls

E. Coarse Focus knob
F. Fine Focus knob

G. Base

H. Light source

I. Iris Diaphragm
J. Condenser lens

K. Mechanical stage

L. Objective lens

M. Nose piece

Larger Eukaryotic Cells (molds, protozoa, helminths) use _____ magnifications like

lower; 4x,10x,40x

Smaller prokaryotic cells (bacteria) uses ______ magnification like

100x