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What is microscopy?
The technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye.
What is micrometry?
A technique used to measure microscopic objects.
Which of the following parts is responsible for holding the specimen in place on a microscope?
What happens to the image viewed through a microscope?
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The calibration constant is calculated using the formula: (stage micrometer spaces / ocular micrometer spaces) × ____
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Ocular micrometers are always reliable for measurement.
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What causes hemolysis in red blood cells?
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Which of the following solutions is isotonic for red blood cells?
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What is the internal condition of the membrane for active dry yeast when it is acidic?
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Heat denatures proteins, halting all living processes.
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Diffusion involves the net movement of solute from an area of _____ concentration to an area of _____ concentration.
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Study Notes
Microscopy and Micrometry
- Microscopy involves using microscopes to view small objects invisible to the naked eye.
- Micrometry measures microscopic objects through ocular micrometers calibrated with stage micrometers.
- Compound light microscopes utilize light and multiple lenses for specimen magnification.
Microscope Components
- Ocular Lens/Eyepiece: Magnifies the specimen for viewing.
- Body Tube: Connects the eyepiece to the revolving nosepiece.
- Revolving Nosepiece: Holds multiple objective lenses.
- Objective Lenses: Each lens magnifies the specimen.
- Arm: Supports the body tube and stage.
- Stage: Holds the specimen in place for viewing.
- Stage Clips: Secure the specimen on the stage.
- Light Source: Provides illumination from below; uses a light source, not a mirror.
- Condenser: Regulates light intensity reaching the specimen.
- Base: Provides stability and support for the microscope.
- Main Adjustment Knob: Used for rough focusing.
- Fine Adjustment Knob: Used for precise focusing.
Image Viewing and Calibration
- Images appear inverted due to the use of convex lenses.
- Calibration constant is calculated using stage micrometer and ocular micrometer measurements.
- Ocular micrometers are preferred for measurements; stage micrometers serve as a larger reference.
- Calibration quantifies the ocular micrometer's divisions for precise measurement.
- Length/width measurements depend on the calibration constant and number of ocular micrometer spaces.
- Linear magnification combines the powers of both ocular and objective lenses.
- Field of View (FOV) decreases as magnification increases; largest at low power objective (LPO).
Cell Structures and Functions
- Mitochondria are essential for cellular packing and sorting.
- Cytoplasm exists between the nucleus and cell membrane, with cytosol being its watery component.
- Protoplasm includes all living material within a cell, excluding the cell wall.
- Vacuoles are absent in plant cells while vesicles are present in animal cells.
Cellular Transport and Membrane Dynamics
- Plasma membrane structure is amphipathic, containing hydrophilic heads and hydrophobic tails.
- Staining effectiveness depends on charge interactions; oppositely charged molecules may not enter cells.
- Methylene blue allows for cell penetration once the outer membrane is lysed (broken down).
Selective Permeability of Plasma Membrane
- Congo red is a weak cationic dye that binds easily to anionic lysosomal sites.
- Active Dry Yeast (Saccharomyces cerevisiae) shows an internal acidic environment due to proton pumping.
- External environments remain basic; pumping out protons increases external alkalinity.
Conditions Affecting Selectivity
- Formalin (40%): Cross-links proteins, halting cellular processes and blocking protein channels.
- Heat: Causes denaturation and breakdown of proteins.
Diffusion and Factors Influencing It
- Diffusion involves the movement of solutes from high to low concentration.
- Collodion films allow for faster diffusion due to smaller particle size.
- Factors influencing diffusion rate include size (surface area) and polarity (hydrophobic nature repels polar molecules).
Osmosis and Cell Behavior
- Using Tradescantia spathacea to demonstrate osmotic behavior in varying solutions.
- Distilled water is hypotonic, leading to turgidity in plant cells.
- Concentrations of NaCl influence tonicity:
- 0.5% NaCl (isotonic/flaccid)
- 1.0% NaCl (hypertonic/plasmolyzed)
Hemolysis in Red Blood Cells
- Erythrocytes exhibit different responses to solutions:
- Distilled water is hypotonic, leading to lysis (cell rupture).
- 0.9% NaCl is isotonic, maintaining normal rbc shape.
- Higher concentrations (10% NaCl) are hypertonic, causing cell shrinkage.
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Description
This quiz covers essential concepts in microscopy and micrometry discussed during the post-lab session. It includes the use of microscopes, techniques for measuring microscopic objects, and the functions of different microscope parts. Test your understanding and retention of these key topics.
