Basic Laboratory Skills: Making Microscopic Measurements : Lab 2d Word of the Day: Magnification: the process of enlarging something Basic Laboratory Skills: Making Microscopic Measurements : Lab 2d MICROSCOPIC MEASUREMENT AND DRAWING

How big is a cell? http://www.cellsalive.com/howbig.htm

How can we determine the size of a specimen under the microscope? Most accurate: Micrometer Ruler Built into ocular Alternative: Estimate using the technique we will do today!

Our Method - Low Power Make a wet-mount of a piece of 1-mm graph paper (10mm2) Count how many millimeters across appear in your field of view in low power (40X - with eyepiece) Convert to micrometers How many micrometers in a millimeter? Record this in results!

Making Microscope Measurements Total view = 2 boxes = 4 mm across= 4000 μm 1 Box = 2 mm 40X 6

Field of Vision Sizes Field of visions for higher powers are based off of the 40X field 100X is 2.5 times smaller then 40X 400X is 10 times smaller then 40X 40X 2.5 times smaller 10 times smaller 100X 400X 7

Fields of Vision 40X = 2 boxes = 4 mm  4000 μm 100X = 2 boxes/2.5 = .8 boxes = 1.6 mm  1600 μm 400X = 2 boxes/10 = .2 boxes = 0.4 mm  400 μm *All measurement are for width across the middle* 8

Field of Vision at High Magnifications You know that… The field of vision is ~400 μm wide You estimate that… The cell takes up about 1/3 of the width You can calculate that… The cell is about 133.3 μm 400*1/3 = 133.3 μm 400X 9

Procedure Make a wet mount of mm grid graph paper. Count how many 1-mm square go across the diameter of the low power field. Convert the diameter measurement from mm to µm. 1 mm = 1000 µm 4. Create a data table and record the size of the low power field in both mm and µm mm µm 40x 100x 400x

Procedure (cont.) 5. Do the division (do NOT measure!) to calculate the sizes of the medium and high power fields. 40X 2.5 x smaller 10x smaller 400X 100X 6. Report the values in both mm and µm in data table

Next!!!!!!! Choose a slide and draw your organism Use details Use shading List power drawn under Make large

Example Paramecium 400X