Micrometry and morphometry and measurement of size_3.ppt
- 1. Micrometery and Morphometry: Use of stage and ocular micrometer. Calibration of ocular micrometer. Size measurement (length, width, diameter).
- 2. Micrometery Micrometer Micrometers used in microscopes are employed to measure the size of microscopic objects. Morphometery the quantitative analysis of form a concept that encompasses size and shape
- 3. 1 km = 1000 m 1 m = 100 cm, and 1 m = 1000 mm 1 cm = 10 mm 1 mm = 1000 µm 1 µm = 1000 nm 1 nm = 1000 pm Length Units
- 5. One division of stage micrometer
- 8. Ocular ruler/Eyepiece reticle scale
- 14. Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat
- 19. 99 divns=1 mm 1 divn= 1/99=0.0101 mm 1 mm = 1000 µm 0.0101*1000=10.1 µm Now we know 1 divn = 10.1 µm If size covers 35 divns 10.1*35=353.5 µm
- 20. Applications ??
- 21. Measurement of cell size: bacterial and eukaryotic Micrometry (micro: microscopic, metry: measurement) is the measurement of the dimensions of microscopic objects in terms of length, breadth, diameter and thickness. Two micrometers are used. Ocular micrometer and scale micrometer ‘ocular micrometer’ is a circular glass disc, which fits into the circular shelf inside the eyepiece.
- 22. Using the required objective, the graduations on the ocular micrometer are calibrated against the standard graduations on the stage micrometer. For calibration, both the micrometer etchings are superimposed by rotating the eyepiece. The number of ocular divisions (O.D.) coinciding with the number of stage divisions (S.D.) is found out. From this, the calibration factor for one ocular division (O.D.) is calculated as follows: If 10 O.D. coincide with 2 S.D., then 10 O.D. = 2 S.D. = 2 x 10 µ = 20 µ (… 1 S.D. = 10 µ) 1 O.D. = 20/10 µ = 2 µ Thus, the distance between two adjacent ocular etchings is 2 µ (i.e. calibration factor is 2 µ).
- 23. Measurement After calibration, the stage micrometer is removed and the microbe, whose dimensions are to be measured, is placed on the stage on a slide and focused. Now, the number of ocular divisions occupied by the microorganism is counted. Then, by multiplying this number of divisions with the calibration factor, the size of the microbe is determined as follows. If the microbe occupies 6 O.D. in length, then length of microbe = 6 x calibration factor = 6 x 2 = 12 µ.
- 24. The average diameter of spherical bacteria is 0.5-2.0 µm. For rod-shaped or filamentous bacteria, length is 1-10 µm and diameter is 0.25-1 .0 µm. E. coli , a bacillus of about average size is 1.1 to 1.5 µm wide by 2.0 to 6.0 µm long. few bacteria are much larger than the average eukaryotic cell (typical plant and animal cells are around 10 to 50 µm in diameter). Microscopes with at least 10x and 40x objectives mm rulers. switching to the 40X objective with the 10X eyepiece gives 400X magnification. Size of bacteria
- 27. 74 divns
- 30. Materials Required Ocular micrometer, stage micrometer, slide, microscope, microbe. Procedure 1. Place ocular micrometer (a circular etched glass piece) in eyepiece of microscope. 2. The stage micrometer is clipped to the stage and the etchings centered by moving the mechanical stage. 3. The low power objective is taken to position. 4. The eyepiece is rotated till the etchings on both the micrometers superimpose. 5. The required objective is taken to position. The required objective is that, using which the whole microorganism can be viewed and it covers the microscopic field to the maximum possible extent.
- 31. 6. Coincide lines on both scales. 7. The calibration factor for the objective used is calculated. 8. In a similar way, calibration factors are calculated for the other objectives. 9. The stage micrometer is removed. 10. The slide containing the microbe to be observed is placed on the stage and focused. 11. The number of ocular divisions covered by the microbe is counted by viewing through the eyepiece. 12. The size of the microorganism is determined by multiplying the number of ocular divisions covered by the microbe with the calibration factor.
- 32. THANKS