26 Questions
Which type of microscopy uses a phase ring to amplify subtle differences in light, increasing contrast between background and specimen?
Phase-contrast
What is the main characteristic of dark-field microscopy?
Light cells on a dark background
Which type of microscopy uses fluorescence to observe cells?
Fluorescence
Which type of microscopy uses a polarizer and prism to enhance subtle differences in cell structure, giving cells a more 3-dimensional appearance?
Differential Interference Contrast (DIC)
What is the main advantage of confocal scanning laser microscopy?
Higher resolution
Which type of microscopy uses electrons instead of visible light to image cell surface structures?
Scanning electron microscopy
What is the main difference between transmission electron microscopy and scanning electron microscopy?
The thickness of the specimen
What is the main purpose of scanning electron microscopy?
To view the surface of an object
What is the main advantage of electron microscopy over light microscopy?
Higher resolution
Which type of microscopy uses visible light and two lenses to magnify an image?
Compound light microscopy
What is the main purpose of staining in bright-field microscopy?
To increase contrast
Which type of stain is commonly used to differentiate bacteria into gram-positive and gram-negative groups?
Differential stain
What is the role of immersion oil in light microscopy?
To increase resolution
What is the main difference between gram-positive and gram-negative bacteria?
Gram-positive bacteria have a thicker cell wall than gram-negative bacteria.
What is the main purpose of the condenser in a compound light microscope?
To focus the light source onto the specimen
What is the main factor that determines the resolution of a light microscope?
The wavelength of light
A compound light microscope requires light and two lenses to increase resolution. The two types of lenses are the ocular and objective lens.
True
A compound light microscope is able to produce bright field, phase-contrast and dark-field all dependent on the amount of light and its direction.
True
A differential stain will divides the bacteria in a mixed culture based on specific characteristics. Stain that are differential in nature requires at least two stains to be completed and observation of these two colours are required.
False
Which of the following of characteristics of gram stain is incorrect?
The staining process for a gram stain starts with a 1 minute flush of crytsal violet on a heat- fixed smear. Then a one-minute flush with iodine. Followed by a counter stain of safrin for one to two minutes.
A gram stain will not work on certain bacterials due to mycolic acid which is attached to the cell wall surface and produces a wax-like hydrophobic coating. Thus the use of an acid stain is required. An acid stain will appear to be blue and purple in colour.
False
Dark-field microscopy is used to see the of a cell.
A laboratory culture is a nutrient-filled substance in which used to grow microorganisms. A defined media cantain precise amounts of pure chemicals (things we now). Complex media are made from digests of microbial, animal or plant products ( a mixture of things we don't exactly know). A medium made with agar, sugar and bone broth is an example of a defined media.
False
What is the difference between selective media and differential media, pick the most correct.
Differential media coantins componds or addivtives that allows microorganisms to be distinguished by the appearance if the colony or surrounding media
The procedure of aseptic technique.
Flame loop, take cap off, flame tube top, place loop in tube, re-flame tube top and recap
A spread plate can be made by adding a small amount of sample onto the culture plate and being spread by glass spreader after sterilization. Then incubate
True
Study Notes
Types of Microscopy
- Phase contrast microscopy uses a phase ring to amplify subtle differences in light, increasing contrast between background and specimen.
- Dark-field microscopy is characterized by increased contrast between background and specimen, making it ideal for observing live cells.
- Fluorescence microscopy uses fluorescence to observe cells.
- Polarized light microscopy uses a polarizer and prism to enhance subtle differences in cell structure, giving cells a more 3-dimensional appearance.
- Confocal scanning laser microscopy has the advantage of increased resolution and decreased noise.
- Scanning electron microscopy uses electrons instead of visible light to image cell surface structures.
- The main difference between transmission electron microscopy and scanning electron microscopy is the direction of electron beam.
- The main purpose of scanning electron microscopy is to study the surface morphology of cells.
Light Microscopy
- Bright-field microscopy uses visible light and two lenses to magnify an image.
- Staining is used in bright-field microscopy to increase contrast between background and specimen.
- Gram stain is a differential stain used to differentiate bacteria into gram-positive and gram-negative groups.
- Immersion oil is used in light microscopy to increase the refractive index of the medium.
Bacterial Characteristics
- The main difference between gram-positive and gram-negative bacteria is the composition of their cell walls.
- Gram-positive bacteria have a thick peptidoglycan layer, while gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.
Compound Light Microscope
- The main purpose of the condenser in a compound light microscope is to focus light onto the specimen.
- The resolution of a light microscope is determined by the wavelength of light used.
- A compound light microscope requires light and two lenses (ocular and objective lens) to increase resolution.
Microbial Growth
- A laboratory culture is a nutrient-filled substance used to grow microorganisms.
- Defined media contain precise amounts of pure chemicals, while complex media are made from digests of microbial, animal, or plant products.
- Selective media are designed to support the growth of specific microorganisms, while differential media are used to differentiate between microorganisms based on specific characteristics.
Aseptic Technique
- Aseptic technique is a procedure used to prevent contamination of microbial cultures.
- A spread plate can be made by adding a small amount of sample onto the culture plate and spreading it using a glass spreader after sterilization.
Test your knowledge on microscopy and laboratory culture of microorganisms in this PowerPoint® lecture presentations quiz. Learn about the different types of microscopes, their magnification abilities, and the importance of resolution in observing microbes. Challenge yourself to distinguish between two adjacent objects and enhance your understanding of these scientific techniques.
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