Lab 2

INET Lab Report 2
Microscope and the Cell Template

Student: Mavon Riley
Email: [e-mail]
Date: 09/05/2014

I. Purpose of the Microscope
II. The Compound Microscope

EXERCISE 2.1 – Label the parts of the compound microscope

1.
Eyepiece
2.
Arm
3.
Course Adjustment
4.
Fine Adjustment
5.
Revolving Nose piece
6.
Objective Lenses
7.
Stage Clips
8.
Stage
9.
Iris Diaphragm Lever
10.
Condenser
11.
Light Source
12.
Base

EXERCISE 2.2 – Calculate microscope magnification

1. Calculate the total magnification for each lens combination (Table 2.1).

Lens
Lens Power
Ring Color
Total Magnification
Unaided Eye
1X
none
1X x 1X = 1X eyepiece 10X none 1X x 10X = 10X
Scanning
4X black 10X x 4X = 40X
Low Power
10X
green
10X x 10X = 100X
High Power
40X
yellow
10X x 40X = 400X
Oil Immersion
100X
red
10X x 100X = 1000X
Table 2.1 Magnification of each lens

III. Viewing Microscope Slides

EXERCISE 2.3 – Focusing the microscope

EXERCISE 2.4 – Specimen orientation

4.
In which direction does the image move?
It moves to the left.

5.
In which direction does the image move?
It moves towards me.

What is the relationship between the movement of the image and the object?
The image always moves in the opposite direction of the object. So if the object moves to the right, the image will move to the left.

IV. Microscopic Measurement

EXERCISE 2.5 – Measure the diameter of the field of view

3. Move the plastic ruler to the left side of the field of view until a single millimeter line is centered on the side of the field of view (Figure 2.7) and measure the diameter of the field of view to the nearest 0.1 mm. Record the measurement. 2.6mm

4.
How wide is the field of view of the scanning power (40X) in micrometers (µm)? 4400

6. Calculate the size of the diameter of the field of view for each objective lens and record the data. Remember that 1mm = 1000 µm.

Lens
Total Magnification
Diameter
mm
Diameter
µm
Scanning
40X
2.6 mm
2600 um
Low Power
100X
1.1 mm
1100 um
High Power
400X
0.3 mm
300 um
Oil Immersion
100X
.176 mm
176 um
Table 2.2 Diameter of the field of view for each objective lens

EXERCISE 2.6 – Estimate the size of a specimen

1. Estimate the length of the specimen (Figure 2.8) under low power (100X).

200 μm 2. Measure the length of the specimen (Figure 2.9)

300 μm What is the relationship between the diameter of the field of view and its power of magnification? It gives you tools in which to estimate the size.

A specimen which fills ¼ of the field of view under an oil immersion lens (1000X) is how long?

400 μm A specimen which fills ¼ of the field of view under a scanning lens (40X) is how long?

650 μm A specimen which fills ¼ of the field of view under a low power lens (100X) is how long?

257 μm A specimen which fills ¼ of the field of view under a high power lens (400X) is how long?

375 μm Draw a typical cheek cell under high power in your lab manual. Enter the estimated cell size below.

40 μm V. Depth of Focus

EXERCISE 2.7 – Determine depth of focus

5. Determine the order of the colored threads and enter your results below:

Top
Red
Middle
Blue
Bottom
Yellow

How is the order of the threads determined? By using the Vertical distance that remains in focus at one time. The depth and color in the order they are stacked.

What diaphragm adjustment should be made to more easily determine the order of the colored threads? The Iris diaphragm level is used to control the amount of light allowed for optimum depth of focus.

Using Figures 2.10 and 2.11, explain how depth of focus can be used to reconstruct structure.

VI. Characteristics of Cells
VII. Prokaryotic Cells

EXERCISE 2.8 – Observe bacteria cells

2.
Which magnification is being used to view the bacteria? 400X

Can you see cell organelles within the cytoplasm? Yes, Prokaryotic Cells can be seen using the oil immersion (1000X TM)

3. Measure the approximate size (μm) of the bacterial cells. 60 um

5. Label the structures of the bacterial cell (Figure 2.12).

1.
Chromosome
4.
Plasmid
2.
Cell wall
5.
Cytoplasm
3.
Surface membrane

VIII. Eukaryotic Cells
A. Animal Cells

EXERCISE 2.9 – Prepare a wet mount of human cheek cells

4. Estimate the size of a typical cheek cell. Record the cell size and magnification used. 400X and 270 um

B. Plant Cells

EXERCISE 2.10 – Prepare a wet mount of Elodea cells

4. Estimate the size of a typical Elodea cell. Record the cell size and magnification used.

Describe the three-dimensional shape of the Elodea cell. Cell wall, nuclei, and chloroplast.

Describe the arrangement of the chloroplasts, nucleus, and vacuole within the cell. The chloroplast is attracted to light and around the outer wall, the nucleus that has the chloroplast appears as a clear amber color and the vacuole makes up the cell interior.

EXERCISE 2.11 – Onion bulb cells

5.
What plant cell organelle is present in the Elodea leaf cell that absent in onion epidermal cell? Chloroplast

What process occurs in the Elodea leaf cell that does not occur in onion epidermal cells? The reparation process

4. Estimate the size of a typical onion cell. Record the cell size and magnification used. 40X and 2600 um

EXERCISE 2.12 – Animal and plant cell structure

1. Use the diagrams in the lab manual to label the parts of both animal and plant cells.

Animal Cells
Plant Cells
1.
Rough endoplasmic reticulum
1.
Ribosomes
2.
Mitochondria
2.
Chloroplast
3.
Centrioles
3.
Peroxisome
4.
Cytoplasm
4.
Nucleolus
5.
Microfilaments
5.
Nucleus
6.
Chromatin
6.

Nuclear envelope
7.
Nucleolus
7.
Amyloplast
8.
Lysosome
8.
Vacuolar membrane
9.
Plasma Membrane
9.
Central Vacuole
10.
Microtubule
10.
Cell Wall
11.
Nucleus
11.
Plasma membrane
12.
Nuclear pours
12.
Mitochondria
13.
Golgi body
13.
Outer Nucleus
14.
Nucleus envelope
14.
Golgi body
15.
Smooth endoplasmic reticulum
15.
Rough endoplasmic reticulum
16.
Ribosomes
16.
Ribosomes

17.
Cytoplasm

Summary Questions

1. Describe the function of each of the following microscope parts:

Eyepiece lens
Located in the upper end of the body tube and focuses light on the retina of the eye. The power of the eyepiece is usually 10X.
Objective lens
Attached to the revolving nosepiece. The number and magnification of the objective lenses vary with the type of microscope. The objective lenses are housed in several steel tubes that are threaded into the revolving nosepiece. The power of the objective lenses is usually 4X, 10X, 40X, and 100X.
Arm
Functions as the handle of the microscope.
Condenser
Located between the diaphragm and the stage aperture. This structure converge light rays from the light rays from the light source so that they pass through the specimen on the slide and into the objective lens.
Revolving nosepiece
This is the part that holds two or more objective lenses and can be rotated to easily change power.
Fine adjustment knob
Located either on top of the course adjustment knob or separately. Manipulating this knob clarifies detail of the specimen.
Coarse adjustment knob
Large knob used to make large movements of the objective lens when focusing on a specimen.

2. Describe the proper procedure for preparing a wet mount. A clean toothpick is used to gently scrape the inside of the cheek, the scrapings are stirred into a drop of water on a clean microscope slide, and a coverslip is added, then take methylene blue dye to stain the cell’s nucleus darker than the cytoplasm. The sample should have been stain by adding drop of iodine solution to one side of the coverslip and touching a piece of absorbent paper to the opposite side of the coverslip.

3. Explain how the microscope is used as an instrument of measurement. It is use to make observations and collecting data in scientific experiments. Use the mm to judge the distance between them and then multiply to find measurement.

4. Determine the magnification of a microscope which has an eyepiece lens (10X) and an objective lens (10X). 10x X 10x = 100X

5. Name three structures common to all cells. A plasma membrane defining the boundary of the living material, a region of DNA (deoxyribonucleic acid, which stores genetic information and a cytoplasm including everything inside the plasma membrane that is not part of the DNA region. Nucleus, cytoplasm, and plasma membrane

6. State three postulates of cell theory. All organisms are composed of one or more cells, the cell is the basic living unit of organization and all cells arise from pre-existing cells.

7. What percentage or fraction of the field of view is occupied by a 500 μm long specimen being viewed under low power (100X)? 1mm

8. Compare magnification, resolving power, and contrast. Magnification is the degree to which the image of a specimen is enlarged, resolving power is how well specimen detail is preserved during the magnifying process and contrast is the ability to see specimen detail against its background. Stains and dyes are added to sections of biological specimens to increase contrast.

9. A specimen fills 1/3 of the field of view under high power (400X). What is the specimen size in µm? 150 um

10. If you are observing an onion epidermal cell under the microscope and the whole image is very pale, what might you do to improve the contrast? I would stain it with iodine, because the stain increases the contrast and will enable me to better view the nucleus and cell wall. By moving the diaphragm

11. Compare the size of bacteria cells you observed with human cheek cells and Elodea cells.
HINT: Use length of measurement for comparison. It looks to have went from bigger to smaller, the human cheek, Elodea, and the bacteria cells.

12. Name three differences between animal and plant cells.
Animal Cells
Plant Cells
1.
Centrioles
1.
Plastids
2.
Round Shape
2.
Rectangular Shape
3.
Only Cell Membrane
3.
Wall and Cell Membrane

13. Do all living plant cells contain chloroplasts? No, not all plants cells have chloroplasts. “Chloroplast is an organelle that specializes in photosynthesis.” Therefore, chloroplast is found in plants cells that receive light. You will not find chloroplast in plants cells underground, because light generally doesn’t reach those cells. If somehow they become exposed to light, they may develop chloroplast.