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Exercise 1. Microscopy. enables one to study objects too small to be seen and examined with the naked eye an optical instrument consisting of a system of lenses that gives sharp, distinct and highly magnified images of minute objects

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exercise 1

Exercise 1


enables one to study objects too small to be seen and examined with the naked eye
  • an optical instrument consisting of a system of lenses that gives sharp, distinct and highly magnified images of minute objects
  • different types depend on usage, source of light, and maximum capacity to enlarge an object
  • uses ordinary room lighting condition, easier to move about and use
a parts and functions
A. Parts and Functions

1. Eyepiece/Ocular – topmost portion

  • Small, removable tube containing lenses with the magnifying power etched on its surface
  • Part where the specimen is viewed
  • Intermediate image projected by the objective is enlarged by the eyepiece.
  • *Hence, the term compound microscope is derived from the fact that the specimen is magnified twice, first by the objective and second by the eyepiece. The final image formed is a virtual image.
2. Extension/Draw tube – Through this tube, the image is projected over a distance

3. Body tube – wide hollow cylindrical tube which provides a short distance for the image/light to pass through

4. Revolving nosepiece – attached beneath the body tube which serves as the base for one or more objectives. It can be rotated to position the appropriate objective to be used (allows convenient exchange of the objectives)
5. Objectives – small narrow tubes containing compound lenses for magnification

a. low power objective (LPO) – shortest, 10x (magnification), 5mm (working distance)

b. high power objective (HPO) – 40-43x, 0.46mm

c. oil immersion objective (OIO) – requires that oil be placed between the objective lens and the coverslip for a distinct image to form, 100x, 0.13mm

d. scanner – allows a wider area of the specimen to be viewed, 2.5x

6. Arm – curved portion connecting the body tube to the base of the microscope; this is where the microscope is held for carrying or tilting; supports the body tube and adjustment knobs; permits adjustment of the stage to a desired angle
7. Adjustment knobs – two pairs of knobs found on both sides of the arm

a. Coarse adjustment knob – larger pair; adjust or moves the body tube, together with the objectives, up and down easily. It is used to bring into focus the specimen to be observed.

b. Fine adjustment knob – smaller pair; adjusts slowly and is used to sharpen the focus

8. Inclination joint – found at the base of the arm which allows the upper portion of the microscope to be tilted

9. Stage – place where the glass slide (which contains the specimen to be observed) is placed; contains the stage clips and a hole

10. Stage clip – holds the slide in place

11. Opening/Aperture – where light passes through

12. Aperture disc – movable; connected to and beneath the stage contains a series of holes with different sizes for the regulation of the incoming light

13. Substage condenser – used to concentrate the incoming light

14. Iris diaphragm – below the condenser; with a movable lever, also for regulating the incoming light

15. Mirror – found at the base of the microscope which is used to direct the light through the opening of the stage

16. Pillar – region connecting the inclination joint with the stand at the base of the microscope. Together they support and hold the microscope in a steady position

17. Base – keeps the microscope steady at any position of the stage

Parfocal – means that the objectives are optically and mechanically designed so that the distance between the specimen and the aerial image is always constant. Slight refocusing with the aid of fine focus knob is sufficient to restore critical sharpness of the image after changing from objective to another, thus the coarse focus knob need not be operated.
c care of the microscope
C. Care of the Microscope
  • Read the manual…
d terms and concepts in microscopy
D. Terms and Concepts in Microscopy
  • Resolving Power
  • Limit of resolution
  • Working distance
  • Field of Vision
  • Magnification (Linear)
  • Parfocal
e calibration of the microscope
E. Calibration of the Microscope
  • *1mm = 1000 micrometers
  • The ocular micrometer is a glass disc with mounted scale. It is inserted into the eyepiece and must be calibrated for the particular objective, eyepiece and tube length employed before measurements are made. The student microscope has a fixed tube length.
  • A stage micrometer is a glass slide with graduations of known intervals. The length of one small division is 0.01 mm or 10 micrometers, whereas one big division is 0.1 mm or 100 micrometers.
1. Calibration of the Ocular Micrometer
  • Use this formula to determine the value of one division on the ocular micrometer:
  • Calibration factor = SM divisions subtended by OM x Value of one SM div

OM division subtended by SM

2. Measurement of the Specimen
  • The specimen is measured by counting the number of divisions it covers on the ocular micrometer. Knowing the calibration factor, you can compute the size of the specimen in micrometers or millimeters.
f techniques for preparing specimens for light microscopy
F. Techniques for Preparing Specimens for Light Microscopy
  • Wet mount technique – organism can be observed in its normal living condition. Simple wet mount involves placing on a glass slide a drop of the specimen which is suspended in a fluid. If the specimen is dry, a drop of water is added to the specimen on the glass slide. A coverslip is placed on top of the specimen to prevent drying and to flatten the specimen in order to avoid the refraction of light.
  • Fixed and Stained preparation
g dissecting microscope
G. Dissecting Microscope
  • consists of a single lens which provides a large and clear field and gives a magnification of 6x to 20x
  • for the study of large or thick specimens
  • useful in examining small organisms and parts of large organisms
  • gives an erect image
  • Hypotonic
  • Isotonic
  • Phospholipid bilayer
  • Capture solar energy and utilize for the synthesis of organic compounds from water and carbon dioxide in a series of enzyme-mediated complex reaction
  • Chloroplasts (thylakoid membranes)

6 CO2 + 12 H2O Light and chlorophyll---) C6H12O6 + 6 H2O + 6 O2

four steps
Four steps

1. Absorption of light (directly light dependent)

H2O + 2 NADP+ light---) 2 H+ + 2 NADPH + O2

2. Electron transport (directly light dependent)

3. ATP generation (directly light dependent)

4. Carbon fixation (indirectly light dependent)

6 CO2 + 12 H2O + 18 ATP + 12 NADPH ---) C6H12O6 + 18 ADP + 12 NADP + 6 H+

  • Slow, controlled release of energy through the enzymatic breakdown of organic substances into simpler products
  • Mitochondria (inner membrane)
  • Aerobic

C6H12O6 + 6 H2O + 6 O2

Enzymes-----) 6 CO2 + 12 H2O + Energy

  • C6H12O6 Enzymes-----) 2CO2 + C2H5OH (ethanol) + Energy
  • C6H12O6 Enzymes-----) 2C3H6O3 (lactic acid) + Energy
cellular respiration in yeast
Cellular Respiration in yeast
  • Respire both aerobically and anaerobically
  • Easily handled
  • If oxygen is available, it will respire both aerobically and anaerobically
exercise 4 mitosis
Exercise 4 Mitosis
  • Prophase – shortening & thickening of chromosomes due to coiling of chromosome thread

- At late prophase – chromosomes can be seen to consist of 2 strands known as sister chromatids which are attached together through the centromere; nuclear membrane and nucleolus are no longer visible at the end of prophase

Metaphase – chromosomes have already shortened to a fraction of their former length and are much thicker

- Chromosomes are now lined up in a single plane across the center of the cell called the metaphase plate or equatorial plane or zone

Anaphase – sister chromatids move to opposite ends or poles of the cell
  • They appear to be pulled apart by thread-like spindle fibers attached to the centromere
  • The centromere of each of the chromatids become totally functional during this stage
  • Upon separation from each other, the chromatids are now considered as individual chromosomes
Telophase – at this point, the chromosomes have reached the opposite poles. They start to uncoil and lengthen. A nuclear envelope reforms about each set of chromosomes, the nucleolus reappears in each pole and cytokinesis takes place. Each daughter cell proceeds to the interphase condition and begin to carry out their physiological fnx
cytokinesis cytoplasmic division
Cytokinesis – cytoplasmic division
  • Animal cell – begins with the formation of cleavage furrow running from the opposite sides of the cell, parallel to the equatorial plate. The furrow becomes progressively deeper, until it cuts completely through the cell producing two new cells. It progresses from the periphery to the middle
Plant cell – forms a plate in the center of the cytoplasm and slowly becomes larger until its edges reach the outer surface. The cell and the cell’s contents are cut in two. It progresses from the middle to the periphery