BIOS242, Week 2, Lab 1
Name:
Lab 3: Microscopy- Observation of Cells
Learning Objectives:
Learn how to use the compound light microscope for observation of cells.
Observe different types of bacteria and identify them based on their shapes.
Observe a variety of eukaryotic cells.
Introduction:
Microbiology is the study of organisms, which cannot be seen with naked eye. You will need help of a microscope to
observe these “tiny animalcules” as they were described by Antoni Von Leeuwenhoek. Microscopes can either be simple
(contains single lens) or compound (contains series of lens systems to achieve higher magnification).
Principle of microscopy: In a compound microscope, the light passes from the specimen into the objective lens which
magnifies the image to 4x, 10x, 40x, or 100x (depending upon the power of objective lens used) which then enters eye
piece and is further magnified 10x. . Final magnification is hence the product of power of objective lens (4x, 10x, 40x, or
100x) multiplied by the power of the eyepiece (10x).
Total Magnification of a Microscope = Magnification of Objective Lens x Magnification of Ocular Lens
Exercise 1: Parts of a Microscope
Eyepiece Lens: the lens at the top of the microscope that you look through.
Arm: Supports the tube and connects the head containing the eyepiece to the base of the microscope
Illuminator: A steady light source (110 volts) used in place of a mirror.
Stage: The flat platform where you place your slides. Stage clips hold the slides in place and can be moved around by
turning two knobs. One of the knobs moves the stage left and right (horizontal movement), the other knob moves the
stage up and down (vertical movement).
Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4X
(scanning), 10X (low power), 40X (high power) and 100X (oil immersion) lenses.
When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X, 400X
and 1000X.
Condenser Lens: The purpose of the condenser lens is to focus the light onto the specimen.
Diaphragm or Iris: Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and
is used to vary the intensity and size of the cone of light that is projected upward into the slide.
Coarse adjustment knob: large, round knob on the side of the microscope used for focusing the specimen; it may move
either the stage or the upper part of the microscope.
This study source was downloaded by 100000840546212 from CourseHero.com on 02-20-2022 07:50:24 GMT -06:00
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, BIOS242, Week 2, Lab 1
Name:
Fine adjustment knob: small, round knob on the side of the microscope used to fine-tune the focus of your specimen
after using the coarse adjustment knob.
Aperture: the hole in the stage that allows light through for better viewing of the specimen.
Parfocal microscope objectives: The specimen being observed remains in focus when magnification is changed; i.e., if
the microscope is switched from a higher power objective (e.g., 40×) to a lower power objective (e.g., 10×), the specimen
remains in focus.
Field of View: Sometimes abbreviated "FOV", it is the diameter of the circle of light that you see when looking into a
microscope. As the power gets greater, the field of view gets smaller.
Complete the Table 1 in the Lab report for calculations of magnification and identifying parts of microscope.
Exercise 2: Observation of Different Types of Bacteria
Materials:
Compound microscope, immersion oil, lens wipes, prepared slides of various bacteria- Rods, cocci and spiral
Notes to Students:
For this exercise, you may have a single slide containing three different types of bacteria or you may have three slides,
each containing only one type of bacteria. Check with your instructor about how many slides you will be observing.
Method:
1. Obtain the preserved slide of a bacteria.
2. Use Appendix A and follow the instructions on how to use a Microscope.
3. Observe the slide under 10X, and then 40X objective lenses.
4. Record and describe your observations made using 40X lens.
5. Make sure to note as many details as possible about the size, shape and color (stain) of bacteria.
6. Use 100X oil immersion lens if needed and record your observations.
Note to Students: Don’t forget to use oil with 100X lens only. After completing the observation, clean the oil
immersion lens with lens wipes to remove oil. Be careful to not contaminate other lenses (4X, 10X, 40X) with oil
as this will cause damage to the other lenses.
7. Repeat the steps 1-6 for slides containing bacteria of different shapes as needed. Record your observations in the
lab report.
Exercise 3: Observation of Eukaryotic Cells- Protozoa and Fungi
Materials:
Compound Microscope, prepared slides of Protozoa and fungus
Method:
Protozoa:
This study source was downloaded by 100000840546212 from CourseHero.com on 02-20-2022 07:50:24 GMT -06:00
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https://www.coursehero.com/file/36678255/Lab3-Microscopy-labdocx/
Name:
Lab 3: Microscopy- Observation of Cells
Learning Objectives:
Learn how to use the compound light microscope for observation of cells.
Observe different types of bacteria and identify them based on their shapes.
Observe a variety of eukaryotic cells.
Introduction:
Microbiology is the study of organisms, which cannot be seen with naked eye. You will need help of a microscope to
observe these “tiny animalcules” as they were described by Antoni Von Leeuwenhoek. Microscopes can either be simple
(contains single lens) or compound (contains series of lens systems to achieve higher magnification).
Principle of microscopy: In a compound microscope, the light passes from the specimen into the objective lens which
magnifies the image to 4x, 10x, 40x, or 100x (depending upon the power of objective lens used) which then enters eye
piece and is further magnified 10x. . Final magnification is hence the product of power of objective lens (4x, 10x, 40x, or
100x) multiplied by the power of the eyepiece (10x).
Total Magnification of a Microscope = Magnification of Objective Lens x Magnification of Ocular Lens
Exercise 1: Parts of a Microscope
Eyepiece Lens: the lens at the top of the microscope that you look through.
Arm: Supports the tube and connects the head containing the eyepiece to the base of the microscope
Illuminator: A steady light source (110 volts) used in place of a mirror.
Stage: The flat platform where you place your slides. Stage clips hold the slides in place and can be moved around by
turning two knobs. One of the knobs moves the stage left and right (horizontal movement), the other knob moves the
stage up and down (vertical movement).
Objective Lenses: Usually you will find 3 or 4 objective lenses on a microscope. They almost always consist of 4X
(scanning), 10X (low power), 40X (high power) and 100X (oil immersion) lenses.
When coupled with a 10X (most common) eyepiece lens, we get total magnifications of 40X (4X times 10X), 100X, 400X
and 1000X.
Condenser Lens: The purpose of the condenser lens is to focus the light onto the specimen.
Diaphragm or Iris: Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and
is used to vary the intensity and size of the cone of light that is projected upward into the slide.
Coarse adjustment knob: large, round knob on the side of the microscope used for focusing the specimen; it may move
either the stage or the upper part of the microscope.
This study source was downloaded by 100000840546212 from CourseHero.com on 02-20-2022 07:50:24 GMT -06:00
1
https://www.coursehero.com/file/36678255/Lab3-Microscopy-labdocx/
, BIOS242, Week 2, Lab 1
Name:
Fine adjustment knob: small, round knob on the side of the microscope used to fine-tune the focus of your specimen
after using the coarse adjustment knob.
Aperture: the hole in the stage that allows light through for better viewing of the specimen.
Parfocal microscope objectives: The specimen being observed remains in focus when magnification is changed; i.e., if
the microscope is switched from a higher power objective (e.g., 40×) to a lower power objective (e.g., 10×), the specimen
remains in focus.
Field of View: Sometimes abbreviated "FOV", it is the diameter of the circle of light that you see when looking into a
microscope. As the power gets greater, the field of view gets smaller.
Complete the Table 1 in the Lab report for calculations of magnification and identifying parts of microscope.
Exercise 2: Observation of Different Types of Bacteria
Materials:
Compound microscope, immersion oil, lens wipes, prepared slides of various bacteria- Rods, cocci and spiral
Notes to Students:
For this exercise, you may have a single slide containing three different types of bacteria or you may have three slides,
each containing only one type of bacteria. Check with your instructor about how many slides you will be observing.
Method:
1. Obtain the preserved slide of a bacteria.
2. Use Appendix A and follow the instructions on how to use a Microscope.
3. Observe the slide under 10X, and then 40X objective lenses.
4. Record and describe your observations made using 40X lens.
5. Make sure to note as many details as possible about the size, shape and color (stain) of bacteria.
6. Use 100X oil immersion lens if needed and record your observations.
Note to Students: Don’t forget to use oil with 100X lens only. After completing the observation, clean the oil
immersion lens with lens wipes to remove oil. Be careful to not contaminate other lenses (4X, 10X, 40X) with oil
as this will cause damage to the other lenses.
7. Repeat the steps 1-6 for slides containing bacteria of different shapes as needed. Record your observations in the
lab report.
Exercise 3: Observation of Eukaryotic Cells- Protozoa and Fungi
Materials:
Compound Microscope, prepared slides of Protozoa and fungus
Method:
Protozoa:
This study source was downloaded by 100000840546212 from CourseHero.com on 02-20-2022 07:50:24 GMT -06:00
2
https://www.coursehero.com/file/36678255/Lab3-Microscopy-labdocx/
