MICROSCOPES Microscope Quiz Friday Jan 28 n

MICROSCOPES

Microscope Quiz Friday –Jan. 28 n n n Label parts of microscope How to use (ex: use coarse knob to find object, adjust diaphragm for light) Total Magnification (eyepiece X objective) How to Measure (field diam. number across) Convert mm to µm (4 mm = 4000 µm)

Compound Light Microscope Parts

Compound Light n. Uses two lenses –ocular –objective n. To bend light

Resolving Power n Being able to tell two objects apart n Measure of “clarity”-how clear it is

Resolving Power n smallest separation between two object points that a given lens (or mirror) can still show as two distinct entities, not one n . . .

Pollen Under 1000 X LM Over 1000 X SEM

MAGNIFICATION n Increase in the apparent size of an object n MULTIPLY THE OCULAR LENS x THE OBJECTIVE – OCULAR 10 x – OBJECTIVE 40 x – WHAT IS THE TOTAL MAGNIFICATION? – 400 x

How do they look different? n Leaf 4 X n Leaf 10 X

ADVANTAGES of CLM: n CAN MAGNIFY UP TO 1000 x n CAN VIEW LIVING THINGS n Resolving power 200 nm or 0. 2 µm

Disadvantages of LM n Objects must be thin or transparent so light can go through them n The image is inverted

Pictures of LM microorganisms Can be stained

Dissecting Light Microscope n Image is NOT inverted n Usually 40 X is the limit

Dissecting Scope Viewing Light-colored stage for dark specimens and dark-colored stage for light ones

Dissection Scope View of Insect Wing

ELECTRON MICROSCOPES n USE MAGNETS TO FOCUS A BEAM OF ELECTRONS –TEM (Transmission Electron Microscope) –SEM (Scanning Electron Microscope)

TEM Advantage Can magnify 1000 X’s more than a light microscope (Uh… 1000 X 1000 = 1, 000 X’s ) n Resolving power 0. 2 nm

TEM Disadvantages n Must be in a vacuum (dead) n Sample must be VERY THIN (less than 0. 2 nm)

TEM Images

SEM: Scanning Electron Microscope Advantages n Electron beam scans the surface n Resolution 10 nm n Magnifies 1, 000 X’s

SEM Disadvantages n Must be in a vacuum (dead) n Cannot see internal structures

SEM Images house fly n n and its mouth

Choose Critter and Change Image n Molecular Expressions Microscopy Primer: Electron Microscopy Interactive Java Tutorials - Virtual Scanning Electron Microscopy

SPM-Scanning Probe Microscope n Viewed ATOMS!!!!!! n Does not need sample in a vacuum n Magnifies n 10 million times

SPM Images (50 um X 1. 4 um) n Steel Surface

SPM Images n DNA

FIRST TO VIEW ATOMS!!!

CHOICES: Diaphragm Objectives Ocular Coarse knob Fine knob Base Revolving nose piece Stage and stage clips Arm condenser Label the parts:

Label the parts: Ocular (eyepiece) Arm Revolving nose piece Objectives Coarse knob Fine knob (little) Stage and stage clips Diaphragm Condenser base

Always begin on lowest lens

n That is, as you increase magnification, the actual field of view becomes proportionally smaller. n 4 OX 100 X 400 X

Use REVOLVING NOSEPIECE – don’t grab lenses

Eye Specimen

Depth of Field = to the thickness of the plane of focus

Viewing “F” with A Light Microscope n Which is an “F” put in a compound light and a dissection light microscope?

Field of View n What is the approximate width in mm? n In µm? (1 mm = 1000 µm) n 4 mm 4000 µm

Why use the letter “e? ”

Do the math: n one millimeter (mm. ) = 1, 000 micrometers µm n So 5. 5 mm = ____ µm n 5500 µm

NOTE!!!!!!!! n The field diameter at high power is proportional to the ratio of the low to high power objectives. n If 40 X is 4000 µm n 400 X is 400 µm

FD = field diameter n Low power FD X low magnification high power magnification = high power FD Use when object is between the mm markers

Why do you need to know Field Diameter? n You may wish to estimate the size of the specimens (e. g. , cells) you will see in lab.

Field of View n What is the approximate size of this cell? In mm? In um? n If 5 fit across… n O. 4 mm n n 400 µm

If the field of view in this question is 2 mm… How long is 2 mm one cell?

If the field of view in this question is 2 mm… If 3 cells fit across then, one cell is: 2 mm 3 =. 67 mm 2 mm

Wet Mount 1. Add drop of water 3. Add cover slip 2. Place Specimen on slide 4. Tap out bubbles

Making a Wet Mount Slide n n Add drop of water Add cover slip