Word of the Day Basic Laboratory Skills Magnification

Word of the Day: Basic Laboratory Skills: Magnification: the Making Microscopic process of enlarging Measurements : Lab 2 d something 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 (10 mm 2) • Count how many millimeters across appear in your field of view in low power (40 X - 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 40 X

Field of Vision Sizes • Field of visions for higher powers are based off of the 40 X field • 100 X is 2. 5 times smaller then 40 X • 400 X is 10 times smaller then 40 X 2. 5 times smaller 100 X 400 X

Fields of Vision • 40 X = 2 boxes = 4 mm 4000 μm • 100 X = 2 boxes/2. 5 =. 8 boxes = 1. 6 mm 1600 μm • 400 X = 2 boxes/10 =. 2 boxes = 0. 4 mm 400 μm *All measurement are for width across the middle*

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… 400 X – The cell is about 133. 3 μm – 400*1/3 = 133. 3 μm

Procedure 1. Make a wet mount of mm grid graph paper. 2. Count how many 1 -mm square go across the diameter of the low power field. 3. 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 40 x 100 x 400 x µm

Procedure (cont. ) 5. Do the division (do NOT measure!) to calculate the sizes of the medium and high power fields. 40 X 2. 5 x smaller 100 X 10 x smaller 400 X 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 – 400 X