microscopes -...

Microscopes

• It is estimated that the human race grows

daily by about 214,000 people.

• It takes only 15 watts of electricity going

through a human body to stop the heart.

Common light bulbs run on about 25 to 75

watts of electricity.

Microscopes

Objectives:

•To name the parts of the microscope

and describe their functions

Microscopes Objectives:

•To name the parts of the microscope and

describe their functions

•To describe how to properly use a

compound microscope.

Microscopes

Objectives:

•To name the parts of the microscope

and describe their functions

•To describe how to properly use a

compound microscope.

•To compare a compound to a light

microscope

•Compound Microscope •Dissection Microscope •Scanning Electron Microscope (SEM) •Transmission Electron Microscope (TEM)

• light illuminated • microscope is two dimensional • commonly used. • View of individual cells, even living

ones. • It has high magnification. • it has a low resolution.

Frog’s blood

1,000x

Paulownia Wood c.s.

200x

• light illuminated.

• image that appears is three

dimensional. It is used for

dissection for larger specimen.

• cannot see individual cells

because it has a low

magnification.

• (also called stereo microscope)

Sunflower with moth

pupa in the stem

10x

Head of a moth pupa

60x

• use electron illumination. • The image is seen in 3-D. • It has high magnification and

high resolution. • The specimen is coated in gold

and the electrons bounce off to give you an exterior view of the specimen.

• The pictures are in black and white.

cockroach antenna

pigeon blood

• is electron illuminated. • This gives a 2-D view. • Thin slices of specimen

are obtained. • The electron beams pass

through this. • It has high magnification

and high resolution.

mitochondrion

bacillus bacteria

dividing

The Electron

Microscope

Allows us to see very high resolution images

PREDATORY ANT WITH PEAR PSYLLA IN ITS MOUTH

SCALES AND SETAE ON LEPIDOPTERA

Dust mite

The Electron

Microscope How does it work?

They use giant electromagnets to sent a stream of electrons over the specimen. This image is then read by a computer.

Light verses

Electron

Microscopes

Light Electron

Means of

Transmitting

image

Ray of light Beam of

electron

Focuses with

Stains tissue with

Slices tissue with

magnification

Type of cells

viewed

Year introduced

Amount of detail

Light verses

Electron

Microscopes

Light Electron

Means of

Transmitting

image


electron

Focuses with Lenses Magnets

Stains tissue with

Slices tissue with

magnification

Type of cells

viewed

Year introduced

Amount of detail

Light verses

Electron

Microscopes

Light Electron

Means of

Transmitting

image


electron


Stains tissue with Colorful dyes Heavy metals

Slices tissue with

magnification

Type of cells

viewed

Year introduced

Amount of detail

Light verses

Electron

Microscopes

Light Electron

Means of

Transmitting

image


electron


Stains tissue with Colorful

dyes

Heavy

metals

Slices tissue with Steel Diamonds

magnification

Type of cells

viewed

Year introduced

Amount of detail

Light verses

Electron

Microscopes

Light Electron

Means of

Transmitting

image


electron


Stains tissue with Colorful dyes Heavy metals


magnification 2000X 250,000 or

more

Type of cells

viewed

Year introduced

Amount of detail

Light verses

Electron

Microscopes

Light Electron

Means of

Transmitting

image


electron



dyes

Heavy

metals



more

Type of cells

viewed

Living or

dead

Dead only

Year introduced

Amount of detail

Light verses

Electron

Microscopes

Light Electron

Means of

Transmitting

image


electron



dyes

Heavy

metals



more

Type of cells

viewed

Living or

dead

Dead only

Year introduced 1660’s 1930’s

Amount of detail

Light versus

Electron

Microscopes

Light Electron

Means of

Transmitting

image


electron



dyes

Heavy

metals



more

Type of cells

viewed

Living or

dead

Dead only

Year introduced 1660’s 1930’s

Amount of detail Flat image 3-D image

• Always carry with 2 hands • Never touch the lenses with your fingers. • Only use lens paper for cleaning • Do not force knobs • Keep objects clear of desk and cords • When you are finished with your "scope",

rotate the nosepiece so that it's on the low power objective, roll the stage down to lowest level, rubber band the cord, then replace the dust cover.

Ocular lens

Body Tube

Revolving Nosepiece

Arm

Objective Lens

Stage

Stage

Clips Coarse adjustment knob

Fine adjustment knob

Base

Diaphragm

Light

Ocular lens

magnifies; where you look through to see the image of your specimen.

They are usually 10X or 15X power. Our microscopes have an ocular lens power of 10x.

arm

supports the tube and connects it to the base

stage

the flat platform where you place your slides

coarse adjustment knob

moves stage (or body tube) up and down

fine adjustment knob

small, round knob on the side of the microscope used to fine-tune the focus of your specimen after using the coarse adjustment knob

base

the bottom of the microscope, used for support

body tube

connects the eyepiece to the objective lenses

revolving nosepiece

the part that holds two or more objective lenses and can be rotated to easily change power

objective lens

Adds to the magnification

Usually you will find 3 or 4 objective lenses on a microscope. They almost

always consist of 4X, 10X, 40X and 100X powers. When coupled with a 10X (most common)

Limits of Resolution •As we focus the microscope to higher powers we see more and more detail, until a certain point. Then objects become blurry and detail is lost. Think of blowing up a picture too big.

•

•Resolution is out ability to distinguish two points as separate.

•Electron Microscopes have a much higher limit of resolution.

Click here to

zoom

http://www.zemote.com/photos/holidays/tree/P1010022.JPG

objective lenses

The shortest lens is the lowest power, the longest one is the lens with the greatest power. Lenses are color coded.

objective lenses

The high power objective lenses are retractable thereby protecting the lens and the slide.

stage clips

Stage clips hold the slides in place.

diaphragm

• controls the amount of light going through the specimen

• rotating disk under the stage. • has different sized holes and is

used to vary the intensity and size of the cone of light

light

makes the specimen easier to see

• start with the lowest power objective lens first and while looking from the side, crank the lens down as close to the specimen as possible without touching it.

• Now, look through the eyepiece lens and focus upward only until the image is sharp. If you can't get it in focus, repeat the process.

• Once the image is sharp with the low power lens, you should be able to simply click in the next power lens and do minor adjustments with the focus knob.

• If your microscope has a fine focus adjustment, turning it a bit should be all that's necessary.

• Continue with subsequent objective lenses and fine focus each time.

Rotate to 40x objective, locate desired portion of specimen in the center of the field. Refocus very carefully so that the specimen is focused as sharply as possible. (Do not alter focus for the Following steps )

Partially rotate so that 40x and 100x objectives straddle the specimen.

Focus only with fine focus. Hopefully, the specimen will come into focus easily. Do not change focus dramatically.

Clean up!: When you have finished for the day, wipe the objective carefully with lens paper to remove all dirt.

General Procedures Make sure all backpacks are out of the aisles before you get a microscope! Always carry the microscope with one hand on the Arm and one hand on the Base.

· Do not wear your glasses, the microscope will focus to your eyesight!

· Keep both eyes open, your brain will learn to ignore the other eye.

What the parts do!

1.the lens you look through, magnifies the specimen ocular (eyepiece)

2. supports the microscope base

3. holds objective lenses nosepiece

4. magnify the specimen (2) high power objective lens low power objective lens

5. supports upper parts of the microscope, used to carry the microscope Arm

6. used to focus when using the high power objective fine focus knob

7. where the slide is placed stage

8. regulates the amount of light reaching the objective lens diaphragm

9. used to focus when using the low power objective coarse focus knob

10. provides light light source

11. hold slide in place on the stage stage clips

Magnification of a Compound Microscope

• Because you are looking through multiple lenses the lenses have a “compounding” effect.

•The eyepiece always magnifies 10X

Eyepiece

Objective Lens

Magnification

Scanning lens (red)

10X

Low Power (yellow)

10X

High Power (blue)

10X


•Each of the objective lenses have their own magnification

Eyepiece

Objective Lens

Magnification

Scanning lens (red)

10X

4X

Low Power (yellow)

10X

10X

High Power (blue)

10X

40X


•You then multiply the eyepiece with the objective lens to

determine the total magnification

Eyepiece

Objective Lens

Magnification

Scanning lens (red)

10X

4X

Low Power (yellow)

10X

10X 100X

High Power (blue)

10X

40X

400X

40X

Other Laboratory Techniques

• Staining

• Dyes are added to slides to bring

out detail and stain certain

features.

• Centrifugation

A device that can spin tubes up

to 20,000X/min. This is used to

separate samples (I.e. parts of

cells

• Cell Culture

• Cells of a particular kind are

grown on plates with all their

required nutrients.

Focusing a Specimen

• Always start on low power or

scanning.

Focusing a Specimen

• Always start on low power or

scanning.

• Focus the specimen using the coarse

adjust.

Focusing a Specimen

• Always start on low power or scanning.

• Focus the specimen using the coarse adjust.

• Re-center. If high power is needed, turn only after re-

centering!

Focusing a Specimen

• Always start on low power or scanning.

• Focus the specimen using the course adjust.

• Re-center. If high power is needed, turn only after re-

centering!

• Now use the FINE FOCUS ONLY for your final

adjustments.

Making a Wet Mount

1. Gather a very thin slice/piece of whatever your specimen is. All samples should be paper thickness or thinner!

2. Place ONE drop of water directly over the specimen. 3. Place the cover slip at a 45 degree angle with one edge touching the water drop, and let go.

Making good drawings 1. Don’t even think of starting your drawing unless you have a pencil

(colored are even better) drawings in pen are unacceptable. This is for two reasons: (a) You can erase pencil! (b) You can shade in areas more easily in pencil

2. In the upper left hand corner of each circle include the specimen name as written on the slide label. In the upper right hand corner, include the magnification (100x or 430x).

3. Label Everything you identify!

100X Cheek cell

nucleus

Cell membrane

microscopes -...

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