Lab 3: The Microscope

The size of Cells and their components

Light microscopes

• Compound light microscope: higher magnificationview small or thinly sliced organism

• Dissecting microscope: low magnificationview larger organismsbut only their surface

Microscope and SlidesCheck Out Procedure

• Sign in and collect prepared slides (under your assigned seat)

• Keep prepared slides in safe place

• Prepared slides have labels

• Remove microscope by its arm and base

• Remove and store bag

Rules for Microscope Use• Low power objective should be in position both at the beginning

and end of lab

• Do not leave slides on microscope when storing it

• Use only lens paper for cleaning lenses (ask instructor for paper)

• Keep the stage clean and dry to prevent rust and corrosion

• Do not remove parts of the microscope

• Keep the microscope dust free by covering it after use

• Report any malfunctioning or if microscope was not stored properly

Field of View is the area of your specimen that is visible through the ocular lens

What happens to the field of view when we increase the magnification?

40X

100X

400X

Microscope specimens

• Prepared slide

• Make your own slidewith staining without staining

Procedure 3.1: Use a compound microscope

- Use prepared slide with letter e

- Focus at low power

Your microscope is parafocal, what does this mean?

- Answer question 1 a and b

Total Magnification is the number of times that the image has been magnified

Microscope uses two sets of lenses to magnify specimen1. ocular lens 2. objective lens

TM = ocular lens x objective lens in use

Procedure 3.2: Magnification

- Examine ocular and objective lenses

- Note magnification of each and estimate total magnification

- Fill out Table 3.1

- Answer question 2 a and b

Procedure 3.4: Depth of field

- Examine slide with colored threads mounted on top of each other

- Answer Question 4 a-c

- Indicate the order of threads from bottom to top- Indicate the code for the slide, for example GS1E

Procedure 3.5: Preparing a wet mount

- Specimen is Spyrogyra

- Answer Question 5 a-c

- 5. Sketchand label chloroplast

Why we sketch in Biology?

You are more likely to remember the specimens and their importantfeatures if you have not only look to the organism several times butphysically drawn a picture to match what you see.

It is therefore important that your drawings represent an image that you will be able to recall at a later date.

As you are also trying to convince me that you have physically lookedat the specimen, your drawing must represent what I know you're looking.

How to sketch in Biology?

The most important aspect of drawing in science is an attention to detail.By paying attention to certain details you will train your brain to recall theinformation you'll need for future tests.

• Make a drawing large and clear so that any features can easily be distinguished and identified. REQUIRMENT: sketches on the front

QUESTIONS in the back.

• You should always draw in pencil.

• Always give a clear full title of what you are illustrating.

• Always include the magnification if a microscope was used.

Procedure 3.6: Use a dissecting microscope

- Follow instructions except for number 4

- Specimen: fern fronds

- Sketch and label sorus

- Answer question 7 c-e

- Answer questions on page 32: 2, 3 and 4

When your done:

• Store microscopes correctly• Return prepared slides, and sign out• Clean up: desk area, slides