Preparing Wet Mount Slides Lesson 2 - Preparing Wet Mount Slides Preparing Wet Mount Slides Using the Microscope Focusing the Microscope Preparing Wet Mounts

Getting into Groups When the teacher says, you will get into pairs and head to a lab bench Each bench has two microscopes… one for each pair, therefore there should only be four people per bench!! Once your ready to go at your bench, PLEASE make sure that you are listening to the instructions at each step so that the class can move smoothly and so that you can have more fun with your partner

Getting Familiar Take a minute to get familiar with the microscope and find the structures you investigated in the last class

Focusing on Specimens Grab a pre-made slide from the front of the room and then follow the next three points to focus on your slide image under high power Secure slide to the stage with stage clips under low power objective lens. The low power objective lens will allow you to the widest area. Use low power to find your specimen on the slide… focus and center the specimen before moving to step 2.

Field of View Each time you increase the objective lens power, you narrow your field of view. Therefore, you must start at low power each time… center & focus before moving to the next objective. The first big number is the magnification power for that lens

Focusing on Specimens Once you've focused & centered using low power, switch to Medium Power. Use the Coarse Knob to refocus and center the specimen again. Again, if you haven't focused on this level, you will not be able to move to the next level. Once centered and focused on medium power, switch to High Power. At this point, ONLY use the Fine Adjustment Knob to focus specimens and never touch or move the slide. If you use the course adjustment to focus, you could crush the stage up into the lens and crack it!!! Focus using the fine adjustment and if the specimen is too dark, try adjusting the diaphragm… allow more light in.

In Your textbooks! Open the text books to page 107 and look at the directions for preparing a wet mount slide Follow the instructions in your textbook to create a wet mount slide of a letter E that you cut out from a news paper

Preparing the Wet Mount Cover Slip Slide Drop of Water

Tips for the Wet Mount Take the specimen you are wanting to look at (in this case the letter “e”) and place it on the dry slide… the letter should be from the small print of a news paper and not a larger head line. Place ONE drop of water using an eye dropper directly over the letter. If you put too much water, then the cover slip will float on top of the water. (Plus too much water is messy) Place the cover slip at a 45 degree angle (approximately) with one edge touching the water drop and then gently let go. Performed correctly the cover slip will perfectly fall over the specimen.

Give It A Try!! Next… Once your wet mount of the “e” is ready, place it on the stage with the “e” right side up and then with your partner, verbally make the following predictions that are outlined in the “give it a try box” on page 107

Finally, the Onion Cell Next… Once you think you are ready, clean off you slides and cover slips With your group, briefly, read the paragraph at the top of page 107 on the onion Once you have done this, The teacher will give you a small piece of onion to prepare a wet mount slide… However, we will also be staining this specimen so look up at the screen for further directions once your slide is done!

How to Stain a Sample The teacher will place one drop of stain (methylene blue found at the front of the room) on the edge of the cover slip Place the flat edge of a piece of paper towel on the opposite side of the cover slip. The paper towel will draw the water out from under the cover slip, and the cohesion of water will draw the stain under the slide As soon as the stain has covered the area containing the specimen, you are finished. The stain does not need to be under the entire cover slip. If the stain does not cover as needed, get a new piece of paper towel and add more stain until it does Be sure to wipe off the excess stain with a paper towel.

How to Stain a Sample Paper towel draws the stain through to the other side staining the sample Drop of the Methyelen Blue

What do you see? Cell wall Cell Nucleus

Scientific Drawings Cell wall Cell Nucleus Cytoplasm Onion cells observed under a high objective lens  total 400 x magnification

Clean Up Time!! Clean up… Store microscopes with the revolving nose piece turned to the low power objective lens Wrap cords under the stage Rinse off slides and cover slips in the sinks… place on the paper towel pad to air dry (only as long as they are not cracked or broken) Wipe down the lab bench if needed Head back to your desk

Next Class In The next class you will be responsible for following the same procedures you just learned You will be given a mark for how well you are able to follow the procedures for using the microscope, focusing to high power, and preparing wet mounts