Exploring Cells with a Compound Microscope

Purpose

The primary objective of this lab is to explore cells by utilizing a compound microscope, enabling us to observe and document the structures and organelles present within cellular specimens.

Time

The expected duration for completing this experiment is approximately 45 minutes.

Research Question

The guiding question for this exploration is: What is the effect of magnification on the visibility of cell organelles using a compound microscope?

Hypothesis

Based on the expected outcome, the hypothesis posits that if cells are examined under higher magnification, an increased number of cellular organelles will be visible to the observer.

Variables

Independent Variable: Magnification power of the microscope.
Dependent Variable: The number of cell organelles observed.
Controlled Variables: The amount of light can also serve as an independent variable; however, if this is altered, the magnification power must be held constant for the experiment.

Safety Precautions

Safety is paramount in a lab environment. Key safety practices include:

Always wearing safety goggles and a lab coat while conducting experiments.
Maintaining purposeful behavior in the lab to avoid accidents.
Using caution while transporting and operating the microscope to prevent damage.
Checking glassware, like microscope slides and cover slips, for any defects prior to use.
Reporting all incidents, regardless of severity, to the supervising teacher.
Ensuring hands are dry when handling electrical devices.

Microscope Handling Guidelines

In order to operate the microscope effectively and avoid strain or damage:

Keep both eyes open while viewing through the ocular lens to prevent eye fatigue.
Begin observations with the lowest power objective lens.
Once the image is in focus using the coarse adjustment knob, refrain from adjusting this knob again when switching to higher power lenses; only use the fine focus to adjust the image.
Ensure that the objective lens does not make contact with the glass slide to avoid damaging either the slide or the lens.

Lab Procedure

Gathering Materials

The materials required for this experiment include:

Compound microscope
Blank glass slide
Cover slip
Dropper
Tap water
Piece of paper with text
Scissors
Forceps
Prepared slide of threads
Prepared slide of epithelial cells (e.g., human cheek cells)

Familiarizing with the Microscope

As you undertake the following steps, document your observations regarding the placement, direction, and function of the microscope's components:

Locate and activate the power button to turn on the light source.
Adjust the diaphragm to observe changes in light intensity.
Experiment with the focus knobs to see which parts of the microscope move.
Lower the stage completely and observe which parts shift when turning the nosepiece.

Preparing a Wet-Mount Slide

To prepare a wet-mount slide:

Cut a letter "e" from the paper and ensure it is positioned right side up on the center of a glass slide using forceps.
Cover the "e" with a drop of water from the dropper.
Carefully position the cover slip at a 45-degree angle above the water drop, lowering the bottom edge to touch the water before allowing the cover slip to settle over the specimen.

Exploring Microscope Features with the Wet-Mount Slide

For each step, record observations through drawings and descriptive notes focused on various attributes such as size, orientation, resolution, contrast, position, and movement.

Start by ensuring the stage is lowered, placing the slide in the correct position, and using the coarse-focus knob to bring the "e" into view, followed by observations.
Attempt initial focusing with the coarse adjustment, then refine the image with the fine-focus knob and document your findings.
Switch to a higher power objective and fine-tune the focus without altering the coarse adjustment to observe the "e" more clearly.
Adjust the diaphragm to evaluate the impact of varying light levels on visibility, noting the clearest observation settings.
Gently shift the slide and document the relative movement of the "e" as observed through the eyepiece.
Return to low power, carefully remove the slide, and prepare for additional observations.

Exploring Depth of Field

Next, assess depth of field:

With the microscope set to low power, place a prepared slide of colored threads and secure it.
Use the coarse-focus knob until part of the threads comes into view, then incrementally raise the stage until they are out of focus again.
With the high-power objective, adjust for clarity by using the fine-focus knob to discern colors for each thread.
Conclude by switching back to low power and removing the slide.

Examining Cell Structures

Finally, it's time to observe cell structures:

Identify and record the title of the prepared slide selected for examination.
Begin with low power, adjusting parameters to locate various structures and organelles; document observations carefully.
Switch to high power, maintaining focus and documenting organelles visible under the microscope distinctly.
Return to low power to conclude the session by removing the slide.

Data Recording

All observations should be systematically recorded in either a lab notebook or the designated data area below.

Microscope and Slide Observations

Step 2: General Microscope Observations

Step 4: Wet-Mount Slide Observations

Unaided Eye

Low-Power Objective: - Observations here.
High-Power Objective: - Observations here.
Largest Diaphragm: - Observations here.
Moving Slide to the Left: - Observations here.

Step 5: Depth of Field Observations

Top Thread Color: - Observations here.

Middle Thread Color: - Observations here.

Bottom Thread Color: - Observations here.

Step 6: Examining Cell Structures

Slide Title: - Observations here.

Cell Structure/Organelle	Observed under Low Power?	Observed under High Power?
Cell membrane	Yes/No	Yes/No
Nucleus	Yes/No	Yes/No
Vacuoles	Yes/No	Yes/No
Ribosomes	Yes/No	Yes/No

Compound Microscope Lab Exploration

Compound Microscope Lab Exploration