viva questions on staining techniques.pptx
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This document contains questions and answers about various staining techniques used to visualize microorganisms under a microscope. Staining improves contrast and allows differentiation of cell structures. Fixatives kill organisms and adhere them to slides to accept stains. Mordants form complexes with stains to aid penetration. Decolorizers remove excess stain. Gram staining differentiates bacteria based on cell wall composition, with Gram-positives having a thicker peptidoglycan layer. Acid-fast staining identifies bacteria with unique cell walls resistant to decolorization. Special staining techniques like Leifson flagella staining use tannic acid precipitation to colorize and enlarge flagella for viewing.
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Rosenbach 1884
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Type I is an immediate reaction mediated by IgE antibodies. It causes conditions like allergic asthma.
Type II involves antibodies binding to antigens on a person's own cells, activating complement and causing cell lysis. It includes conditions like autoimmune hemolytic anemia.
Type III occurs when immune complexes are deposited in tissues, activating complement and causing inflammation and tissue damage. Examples are serum sickness and lupus nephritis.
Type IV is a delayed reaction mediated by T cells and monocytes/macrophages. It causes conditions like contact dermatitis and tuberculosis.
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This document provides information about dyes, stains, and staining methods used in microscopy. It begins with definitions of stains and dyes, explaining that stains are used to facilitate examination under a microscope while dyes are compounds that impart color. It then classifies biological stains as acidic, basic, neutral, metachromatic, or fluorescent based on their chemical properties. Various staining techniques are described including simple staining, negative staining, Gram staining, and acid-fast staining. Specific staining methods and the mechanisms of how they work are explained for simple staining, Gram staining, and acid-fast staining.
Staining
This document provides information about dyes, stains, and staining methods used in microscopy. It begins with definitions of stains and dyes, explaining that stains are used to facilitate examination under a microscope while dyes are compounds that impart color. It then classifies biological stains as acidic, basic, neutral, metachromatic, or fluorescent based on their chemical properties. Various staining techniques are described including simple staining, negative staining, Gram staining, and acid-fast staining. Specific staining methods and the mechanisms of how they work are explained for simple staining, Gram staining, and acid-fast staining.
Lecture 7.ppt
Staining techniques are used to enhance contrast and visibility of structures under the microscope. There are several types of staining including simple staining using one dye, differential staining using multiple dyes to distinguish structures, and special staining for specific structures like capsules, endospores, and flagella. The choice of stain depends on factors like the chemical composition and charge of the dye. Common stains used are basic dyes that bind to negatively charged cell components and acid dyes that stain the background. Differential stains include Gram stain and acid-fast stain that classify bacteria based on cell wall differences in staining.
Staining Methods.pptx
This document discusses various bacterial staining methods including acidic, basic, neutral, and differential staining. It describes how bacterial smears are prepared and the two main types of staining: positive staining, where bacteria appear colored against a clear background; and negative staining, where bacteria remain clear against a colored background. Gram staining and acid-fast staining are discussed as examples of differential staining techniques. Gram staining distinguishes bacteria based on cell wall composition as gram-positive or gram-negative. Acid-fast staining is used to identify mycobacteria using the Ziehl-Neelsen method based on their high lipid and waxy cell walls that resist decolorization by acid.
Bacterial staining
this presentation involves a comprehensive outlines regarding the most common different methods used in diagnostic microbiology to stain bacteria and their structures
MICROBIOLOGIST Staining Techniques questions .pptx
This document discusses various staining techniques used to visualize bacteria and other microorganisms under the microscope. It addresses questions related to staining Gram positive and Gram negative bacteria, acid-fast staining techniques used for Mycobacterium and Nocardia, and staining metachromatic granules found in some bacteria like Corynebacterium diphtheriae. The document provides explanations for different staining methods and how they can be used to distinguish characteristics of various microorganisms.
Types of staining techniques
This document discusses various staining techniques used to visualize microorganisms under a light microscope. It describes simple staining which uses a single dye and differential staining techniques like Gram staining and acid-fast staining that use multiple dyes to distinguish between cell types. Gram staining distinguishes Gram-positive from Gram-negative bacteria based on differences in cell wall structure. Acid-fast staining identifies acid-fast bacteria that resist decolorization by acid-alcohol solutions, like Mycobacterium tuberculosis. Other techniques discussed include capsule staining to visualize the polysaccharide capsule of certain bacteria and wet mount preparations to directly observe motility without staining.
Preparing smears for staining
This document discusses procedures for preparing and staining microbial smears and slides. It describes how microbes are fixed to slides through air drying or heat, and then stained using simple, differential or special staining techniques. Key points covered include how gram staining classifies bacteria as either gram-positive or gram-negative based on cell wall structure and staining properties, and how acid-fast staining identifies mycobacteria by their lipid-rich cell walls. Negative staining can reveal capsules around cells.
Different stains
This document discusses procedures for preparing and staining microbial smears and slides. It describes how microbes are fixed to slides through air drying or heat, and then stained using simple, differential or special staining techniques. Key points covered include how gram staining classifies bacteria as either gram-positive or gram-negative based on cell wall structure and staining properties, and how acid-fast staining identifies mycobacteria by their lipid-rich cell walls. Negative staining can reveal capsules around cells, while endospore staining targets bacterial spore structures.
Gram staining
This document provides information on preparing smears for staining and describes different staining techniques used to examine microorganisms under a microscope. It explains that microbes must first be fixed to a slide before staining. Common staining methods include simple stains that highlight overall cell structure, and differential stains like Gram staining and acid-fast staining that distinguish between bacterial types based on cell wall composition. Special stains are also used to identify specific structures like capsules and endospores.
Bacterial Staining, Staining and it's types, Illustratec with detailed descri...
Staining and it's types. Procedure of various types of staining. Briefly discussed with detailed illustrations.
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The document discusses various common staining techniques used in microbiology. It begins by explaining the purpose of staining and some key terms like stain, staining, and fixation. It then describes different types of stains including simple stains like methylene blue and differential stains like Gram staining. Gram staining technique and the gram positive and gram negative reactions are explained in detail. Another differential staining method discussed is acid-fast staining using Ziehl-Neelsen stain for tuberculosis diagnosis. Various staining procedures and their applications are outlined.
A presentaion on bacterial staining
Bacterial staining techniques are used to make bacteria visible under a microscope since they are otherwise transparent or colorless. There are different types of stains that are either positively or negatively charged and bind to structures in bacterial cells. Simple staining uses a single stain while differential staining uses two contrasting stains to distinguish cell types. Gram staining differentiates bacteria based on cell wall composition and acid fast staining identifies mycobacteria based on their waxy cell walls. Special stains can reveal additional structures like capsules or spores. Staining allows visualization of bacterial morphology, arrangements, and differentiation of types for identification and study.
Why is it that the Grams stain is not appropriate for acid fast ba.pdf
Why is it that the Gram\'s stain is not appropriate for acid fast bacterium?
Solution
During staining in microbiology, microbes are coloured or dyed so that their structure can be
viewed against a lighter background. There are different staining techniques such as direct(Dye
binds to the cell surface and all the microbes are stained alike),differential(based on their specific
cell surface different microbes get stained differently) special (usually a particular organelle is
targeted)and negative staining(back ground is stained instead of microbes) Gram stain is a
differential stain where the bacteria with a thick peptidoglycan layer around the cells are stained
with violet colour and those with an additional lipopolysaccharide layer will be stained pink. To
understand this lets take a look at Gram staining procedure. First of all bacterial culture is
smeared onto a glass slide and is heat fixed so that during the washes in the procedure the
bacteria stay fixed onto the slide. Primary stain crystal violet is added onto the slide and the dye
seperates into ions which penetrate or enter the cell membranes of both Gram positive and
negative cells. Next iodine is added onto the slide which forms huge complexes with crystal
violet. Then a dye remover usually called as decolouriser such as alchohol or acetone is used to
remove the stain. In Gram negative bacteria the outer most membrane is lost during the treatment
with alchohol whereas in the case of gram positive bacteria the dye is trapped inside the cell
membrane. A secondary stain saffronin is used and which gives pink colour to Gram negative
bacteria. Now coming to acid-fast bacteria, they have a compound called mycolic acid in their
cell walls and are resistant to decolourisation after the acid treatment and alchohol and hence
would not lose colour and appear violet. As we can see these organism can be easily confused
with Gram positive bacteria which also do not lose stain not because they are resistant to acids
but they have the crystal violet dye trapped in their cell membrane..
Staining Methods.pdf
This document discusses different staining techniques used to identify bacteria under a microscope. It describes simple staining which identifies morphological characteristics using a single dye. Negative staining uses an acidic dye to stain the background while leaving unstained bacteria visible. Gram staining differentiates between gram-positive and gram-negative bacteria using multiple stains. Acid-fast staining identifies bacteria with wax-like cell walls that retain dye after acid treatment. These staining methods enhance contrast and visibility of bacteria for analysis under a microscope.
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- 2. Q. What is objective of staining? Improves visibility by greater contrast between the organism and the background, differentiate various morphological types (by shape, size, arrangement, etc.). Q. What are the functions/Role of fixative? It kills the organisms; (2) it causes the organisms to adhere to the slide; and (3) it alters the organisms so that they more readily accept stains (dyes)”. Q. What is Mordant? It is a chemical that forms an insoluble complex with the stain and fixes it or causes the stain to penetrate more deeply into the cell. Ex. Gram’s iodine Q. What is Decolorizer? It is a chemical used to remove the excess stain in indirect regressive staining. ex, Ethanol in Gram’s staining.
- 3. Q. Define stain: STAIN is defined as coloring agent used for coloring biological material. A stain is an organic compound containing a benzene ring plus a chromophore and an auxochrome group. Q. In capsule staining Congo red stains what? –Background Q. Why colour change is seen in case of congo red? Due to acetic acid pH is shifted to the acidic side and due to which congo red stain turns red to blue in colour that is why the colour of background changes from red to blue in colour. Q. Which dye stains endospore in Schaeffer and Fultons Method ? -Malachite green Q. Why heating is required in endospore staining? Heating will make the spore wall more permeable to the malachite green which was previously resistant.
- 4. Q. In Dorners Method of endospore staining which dye soln stain’s background? -Nigrosin soln Q. What is Acid Fastness? Acid-fastness is a physical property of certain bacterial, has resistance to decolorization by acids during staining procedures. Due to the unique cell wall structure, we can identify these bacteria using a stain called an acid fast stain. Q. What is used as Mordant in ZN staining? -Steam Heat / Heat. Q. What is used as Decolorizer in ZN staining? - depending on sample it can be 1% or 5% or 20% H2SO4 and 95% Alcohol. Q. What is used as Counter Stain in ZN staining? - Malachite green or Methylene blue.
- 5. Q. In Gram staining what is used as mordent? - Grams Iodine Q. Safranin in Gram staining is a primary stain or counter stain? – Counter stain Q. Gram staining differentiates bacteria based on? – Cell wall composition Q. What is a difference between Cell wall composition of Gram positive and Gram negative bacteria? Gram-negative bacteria has a thin peptidoglycan cell wall, and is surrounded by an outer membrane containing lipopolysaccharide. Gram-positive bacteria lack an outer membrane but are surrounded by layers of peptidoglycan- many times thicker than is found in the Gram-negatives. Q. What is Monochrome staining? Using one dye for staining purpose either primary or counter stain just to study shape or morphology.
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