Microscopy and Staining Techniques

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Questions and Answers

Which microscopy technique is used to reveal fine surface structures of microorganisms?

Bright Field Microscopy

Transmission Electron Microscopy

Fluorescent Microscopy

Scanning Electron Microscopy (correct)

Cationic dyes are acidic and negatively charged.

False

What is the purpose of heat fixation in microscopy?

To destroy microorganisms, adhere them to the slide, and prepare them for staining.

The __________ stain distinguishes between Gram-positive and Gram-negative cells.

Gram Signup and view all the answers

Match the following staining techniques with their descriptions:

Simple stain = Uses a single dye to show cell shapes Differential stain = Uses two or more dyes for structural differences Negative staining = Specimen resists taking up a stain Acid-Fast stain = Identifies bacteria with waxy cell walls Signup and view all the answers

What is the primary function of the ocular micrometer?

To measure objects viewed through the microscope Signup and view all the answers

The total magnification of a microscope is obtained by adding the magnifying powers of the ocular and objective lenses.

False Signup and view all the answers

What are the two most common types of electron microscopy?

Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) Signup and view all the answers

In _______ microscopy, a beam of electrons is used instead of light to produce high-resolution images.

electron Signup and view all the answers

Match the following types of microscopy with their characteristics:

Bright-Field Microscopy = Standard method for viewing stained specimens Fluorescence Microscopy = Uses fluorescent markers to visualize cells Confocal Microscopy = Provides sharp images at various depths Digital Microscopy = Utilizes digital cameras to capture images Signup and view all the answers

What does resolving power (RP) refer to in microscopy?

The distance between two objects that can be distinguished Signup and view all the answers

Shorter wavelengths provide greater resolution in light microscopy.

True Signup and view all the answers

What is the effect of refraction on light?

The bending of light as it passes from one medium to another of different density. Signup and view all the answers

The numerical aperture (NA) relates to the extent that light is concentrated by the __________ lens.

condenser Signup and view all the answers

Match the following terms with their definitions:

Reflection = Light bounces back from an object Transmission = Light passes through an object Absorption = Light is taken up by an object Diffraction = Bending of light waves around obstacles Signup and view all the answers

Which of these is NOT a type of light interaction?

Magnetism Signup and view all the answers

The concept of wavelength is unrelated to the measurement of light.

False Signup and view all the answers

What is the primary benefit of using immersion oil in microscopy?

To improve resolution by increasing the numerical aperture. Signup and view all the answers

Study Notes

Microscopy and Staining

Microscopy is the technology of making very small things visible to the human eye.
Units of measurement:
- Milli = one thousandth (10^-3 m)
- Micro = one millionth (10^-6 m)
- Nano = one billionth (10^-9 m)
Relative sizes of objects are depicted on a scale.
- Includes atoms, amino acids, DNA, proteins, ribosomes, viruses, Chlamydia, Rickettsia, Mitochondrion, Bacteria, Chloroplast, Red blood cell, Large protozoa, Human egg, Tick, Human heart, Dog.
Bacteria are present on the tip of a needle. The image of this is displayed in an electron microscope
Resolution: refers to the ability to see two items as separate and distinct units.
Light microscopy uses wavelengths of visible and UV light for viewing. The shorter the wavelength, the better the resolution.
Properties of light:
- Reflection: Light bounces off an object.
- Transmission: Light passes through an object.
- Absorption: Light is absorbed by an object.
Refraction: Light bends as it moves from one medium to another of different density. Index of refraction measures the speed of light through a material.
Immersion oil is used with microscopes to reduce the refraction of light.
Diffraction: diffraction of light that causes the light to spread out when passing through an opening or around an object.
Light microscopy use different kinds of light microscopes
Total magnification is calculated by multiplying the objective lens magnification by the ocular lens magnification.
There are various types of microscopes including:
- Bright-Field Microscopy
- Dark-Field Microscopy
- Phase-Contrast Microscopy
- Nomarski (Differential Interference Contrast) Microscopy
- Fluorescence Microscopy
- Confocal Microscopy
- Digital Microscopy
Techniques for light microscopy:
- Wet mounts: Used to view living microorganisms.
- Smears: Used to view dead microorganisms
- Heat fixation: is performed on smears to kill the microorganisms and adhere to slide
Different types of staining:
- Simple stain: Uses a single dye.
- Differential stain: Uses two or more dyes to distinguish between organisms.
- Gram stain differentiates between Gram-positive and Gram-negative bacteria.
- Ziehl-Neelsen acid-fast stain is used to identify acid-fast bacteria.
- Negative staining is used when the specimen doesn't take up the stain.
- Schaeffer-Fulton spore stain is used to stain bacterial spores.
Electron microscopy: Uses a beam of electrons instead of light and electromagnets to focus it
Parts of a modern microscope are illustrated
Electron microscope cross-section and Modern Scanning Electron Microscope illustrations are provided
Image of Paramecium and an electron microscope image of it, both are shown at differing magnifications.
Freeze-fracture and freeze-etching techniques prepare samples to be observed with an electron microscope.

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Description

Explore the fascinating world of microscopy and staining techniques. This quiz covers essential concepts including units of measurement, resolution, and the relative sizes of various biological entities. Test your knowledge on how these techniques enhance our understanding of microscopic life.