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They must be only 24 hours old or less. Any older will give false positives or incorrect readings.
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If at the end of gram staining both the gram positive and gram negative bacteria appear red what is the most likely explanation?
Contamination or old culture.Type your answer here...
Why must fresh bacterial cultures be used in a Gram stain?
Why must young cultures be used when doing a Gram stain Young cultures must be used so the crystal violet can stick to the cell walls of Gram positive bacteria. The cell walls break down in old cultures and the staining process is not accurate
What can result in a gram-positive organism staining gram-negative?
The following characteristics are generally present in a Gram-positive bacterium.cytoplasmic lipid membrane teichoic acids and lipoids are present, forming lipoteichoic acids which serve to act as chelating agents, and also for certain types of adherence.thick peptidoglycan layercapsule polysaccharides (only in some species) if present, it contains two rings for support as opposed to four in Gram-negative bacteria because Gram-positive bacteria have only one membrane layer.flagellum (only in some species)Although there is only difference in gram positive and negative is of cell wall as :The Gram positive cell wallThe Gram positive cell wall is characterised by the presence of a very thick peptidoglycan layer, which is responsible for the retention of the crystal violet dyes during the Gram staining procedure. It is found exclusively in organisms belonging to the Actinobacteria (or high %G+C Gram positive organisms) and the Firmicutes (or low %G+C Gram positive organisms). Bacteria within the Deinococcus-Thermus group may also exhibit Gram positive staining behaviour but contain some cell wall structures typical of Gram negative organisms. Imbedded in the Gram positive cell wall are polyalcohols called teichoic acids, some of which are lipid-linked to form lipoteichoic acids. Because lipoteichoic acids are covalently linked to lipids within the cytoplasmic membrane they are responsible for linking the peptidoglycan to the cytoplasmic membrane. Teichoic acids give the Gram positive cell wall an overall negative charge due to the presence of phosphodiester bonds between teichoic acid monomers.The Gram negative cell wallUnlike the Gram positive cell wall, the Gram negative cell wall contains a thin peptidoglycan layer adjacent to the cytoplasmic membrane, which is responsible for the cell wall's inability to retain the crystal violet stain upon decolourisation with ethanol during Gram staining. In addition to the peptidoglycan layer the Gram negative cell wall also contains an additional outer membrane composed by phospholipids and lipopolysaccharides which face into the external environment. The highly charged nature of lipopolysaccharides confer an overall negative charge to the Gram negative cell wall. The chemical structure of the outer membrane lipopolysaccharides is often unique to specific bacterial strains (i.e. sub-species) and is responsible for many of the antigenic properties of these strains.As a phospholipid bilayer, the lipid portion of the outer membrane is largely impermeable to all charged molecules. However, channels called porins are present in the outer membrane that allow for passive transport of many ions, sugars and amino acids across the outer membrane. These molecules are therefore present in the periplasm, the region between the plasma membrane and outer membrane. The periplasm contains the peptidoglycan layer and many proteins responsible for substrate binding or hydrolysis and reception of extracellular signals. The periplasm is thought to exist as a gel-like state rather than a liquid due to the high concentration of proteins and peptidoglycan found within it. Because of its location between the cytoplasmic and outer membranes, signals received and substrates bound are available to be transported across the cytoplasmic membrane using transport and signalling proteins imbedded there.
Can you do a gram stain from 3 day old nutrient agar plate or should i do anohter t streak and let it grow for one day nd then do gram stain?
there should be no problem with doing a gram stain on a 3 days old bacteria strain unless your working with spore making bacteria, then you would need to do another streak, unless your familiar with spore stain methods but you should keep the bacteria cold at 4 degrees if you dont want them to die.
Why do gram negative cells stain pink?
Gram negative bacteria actually stain red because they have a less complex cell wall than Gram positive bacteria and they are easily decolorised by the decoloriser acetone alcohol. Hence they take up the colour of the counter stain safranin which is red during the Gram staining procedure.
If at the end of gram staining both the gram positive and gram negative bacteria appear red what is the most likely explanation?
Contamination or old culture.Type your answer here...
Why must fresh bacterial cultures be used in a Gram stain?
Why must young cultures be used when doing a Gram stain Young cultures must be used so the crystal violet can stick to the cell walls of Gram positive bacteria. The cell walls break down in old cultures and the staining process is not accurate
Why is it necessary to use a young culture 24-hr old culture in gram staining?
less than 24 hours old. Older cultures tend to lose the ability to retain stains.
Does the age of the culture affect the gram staining reaction?
Yes, the age of the culture may influence the results of the stain. With the current theory behind gram staining, it is thought that in gram-positive bacteria, the crystal violet and iodine combine to form a larger molecule that precipitates out within the cell. The alcohol/acetone mixture then causes dehydration of the multilayered peptidoglycan in the gram-positive call wall, thus decreasing the space between the molecules and causing the cell wall to trap the crystal violet-iodine complex within the cell. In the case of gram-negative bacteria, the alcohol/acetone mixture, being a lipid solvent, dissolves the outer membrane of the gram-negative cell wall (and may also damage the cytoplasmic membrane to which the peptidoglycan is attached). The thin layer of peptidoglycan is unable to retain the crystal violet-iodine complex and the cell is decolorized. It is important to note that gram-positivity (the ability to retain the purple crystal violet-iodine complex) is not an all-or-nothing phenomenon but a matter of degree. There are several factors that could result in a gram-positive organism staining gram-negatively: 1. The method and techniques used. Overheating during heat fixation, over decolorization with alcohol, and even too much washing with water between steps may result in gram-positive bacteria losing the crystal violet-iodine complex. 2. The age of the culture. Cultures more than 24 hours old may lose their ability to retain the crystal violet-iodine complex. 3. The organism itself. Some gram-positive bacteria are more able to retain the crystal violet-iodine complex than others.
What can result in a gram-positive organism staining gram-negative?
The following characteristics are generally present in a Gram-positive bacterium.cytoplasmic lipid membrane teichoic acids and lipoids are present, forming lipoteichoic acids which serve to act as chelating agents, and also for certain types of adherence.thick peptidoglycan layercapsule polysaccharides (only in some species) if present, it contains two rings for support as opposed to four in Gram-negative bacteria because Gram-positive bacteria have only one membrane layer.flagellum (only in some species)Although there is only difference in gram positive and negative is of cell wall as :The Gram positive cell wallThe Gram positive cell wall is characterised by the presence of a very thick peptidoglycan layer, which is responsible for the retention of the crystal violet dyes during the Gram staining procedure. It is found exclusively in organisms belonging to the Actinobacteria (or high %G+C Gram positive organisms) and the Firmicutes (or low %G+C Gram positive organisms). Bacteria within the Deinococcus-Thermus group may also exhibit Gram positive staining behaviour but contain some cell wall structures typical of Gram negative organisms. Imbedded in the Gram positive cell wall are polyalcohols called teichoic acids, some of which are lipid-linked to form lipoteichoic acids. Because lipoteichoic acids are covalently linked to lipids within the cytoplasmic membrane they are responsible for linking the peptidoglycan to the cytoplasmic membrane. Teichoic acids give the Gram positive cell wall an overall negative charge due to the presence of phosphodiester bonds between teichoic acid monomers.The Gram negative cell wallUnlike the Gram positive cell wall, the Gram negative cell wall contains a thin peptidoglycan layer adjacent to the cytoplasmic membrane, which is responsible for the cell wall's inability to retain the crystal violet stain upon decolourisation with ethanol during Gram staining. In addition to the peptidoglycan layer the Gram negative cell wall also contains an additional outer membrane composed by phospholipids and lipopolysaccharides which face into the external environment. The highly charged nature of lipopolysaccharides confer an overall negative charge to the Gram negative cell wall. The chemical structure of the outer membrane lipopolysaccharides is often unique to specific bacterial strains (i.e. sub-species) and is responsible for many of the antigenic properties of these strains.As a phospholipid bilayer, the lipid portion of the outer membrane is largely impermeable to all charged molecules. However, channels called porins are present in the outer membrane that allow for passive transport of many ions, sugars and amino acids across the outer membrane. These molecules are therefore present in the periplasm, the region between the plasma membrane and outer membrane. The periplasm contains the peptidoglycan layer and many proteins responsible for substrate binding or hydrolysis and reception of extracellular signals. The periplasm is thought to exist as a gel-like state rather than a liquid due to the high concentration of proteins and peptidoglycan found within it. Because of its location between the cytoplasmic and outer membranes, signals received and substrates bound are available to be transported across the cytoplasmic membrane using transport and signalling proteins imbedded there.
Can you do a gram stain from 3 day old nutrient agar plate or should i do anohter t streak and let it grow for one day nd then do gram stain?
there should be no problem with doing a gram stain on a 3 days old bacteria strain unless your working with spore making bacteria, then you would need to do another streak, unless your familiar with spore stain methods but you should keep the bacteria cold at 4 degrees if you dont want them to die.
Why is time an important factor in simple staining?
In Gram staining, some bacterial species will become Gram variable meaning they produce a false reaction for the following reasons: decolrized too long, too young/old of culture, stained too long. Also, time is important simply because you don't want to over or under stain. You won't be able to see your specimen as well.
Does the age of the culture affect the gram stain?
Yes, the age of the culture may influence the results of the stain. With the current theory behind gram staining, it is thought that in gram-positive bacteria, the crystal violet and iodine combine to form a larger molecule that precipitates out within the cell. The alcohol/acetone mixture then causes dehydration of the multilayered peptidoglycan in the gram-positive call wall, thus decreasing the space between the molecules and causing the cell wall to trap the crystal violet-iodine complex within the cell. In the case of gram-negative bacteria, the alcohol/acetone mixture, being a lipid solvent, dissolves the outer membrane of the gram-negative cell wall (and may also damage the cytoplasmic membrane to which the peptidoglycan is attached). The thin layer of peptidoglycan is unable to retain the crystal violet-iodine complex and the cell is decolorized. It is important to note that gram-positivity (the ability to retain the purple crystal violet-iodine complex) is not an all-or-nothing phenomenon but a matter of degree. There are several factors that could result in a gram-positive organism staining gram-negatively: 1. The method and techniques used. Overheating during heat fixation, over decolorization with alcohol, and even too much washing with water between steps may result in gram-positive bacteria losing the crystal violet-iodine complex. 2. The age of the culture. Cultures more than 24 hours old may lose their ability to retain the crystal violet-iodine complex. 3. The organism itself. Some gram-positive bacteria are more able to retain the crystal violet-iodine complex than others.
What effect does the age of a culture have on its gram stain?
Yes, the age of the culture may influence the results of the stain. With the current theory behind gram staining, it is thought that in gram-positive bacteria, the crystal violet and iodine combine to form a larger molecule that precipitates out within the cell. The alcohol/acetone mixture then causes dehydration of the multilayered peptidoglycan in the gram-positive call wall, thus decreasing the space between the molecules and causing the cell wall to trap the crystal violet-iodine complex within the cell. In the case of gram-negative bacteria, the alcohol/acetone mixture, being a lipid solvent, dissolves the outer membrane of the gram-negative cell wall (and may also damage the cytoplasmic membrane to which the peptidoglycan is attached). The thin layer of peptidoglycan is unable to retain the crystal violet-iodine complex and the cell is decolorized. It is important to note that gram-positivity (the ability to retain the purple crystal violet-iodine complex) is not an all-or-nothing phenomenon but a matter of degree. There are several factors that could result in a gram-positive organism staining gram-negatively: 1. The method and techniques used. Overheating during heat fixation, over decolorization with alcohol, and even too much washing with water between steps may result in gram-positive bacteria losing the crystal violet-iodine complex. 2. The age of the culture. Cultures more than 24 hours old may lose their ability to retain the crystal violet-iodine complex. 3. The organism itself. Some gram-positive bacteria are more able to retain the crystal violet-iodine complex than others.
Why do gram negative cells stain pink?
Gram negative bacteria actually stain red because they have a less complex cell wall than Gram positive bacteria and they are easily decolorised by the decoloriser acetone alcohol. Hence they take up the colour of the counter stain safranin which is red during the Gram staining procedure.
How does bacterium age affect gram staining results?
When you are doing your gram stain, you are looking for gram negative and gram positive cells by how they take on the color of the stains that you have applied. The cells would be either pink or purple which would indicate the negative or positive. The age of the cell does not matter for the sake of gram staining. You are looking for negative or positive. The results would lead you to choosing what medication (antibiotics) to use. Some antibiotics work only on gram negative bacteria and some on gram positive. Wrights staining is where you are looking for the age of the cells for a CBC differential. By identifying the 1. type of cell and 2. age of the cell, you can indicate what is termed as a shift to the left or right. As a cell ages it turns from a one segment (youth) to a hyper- segmented (old) cells. The cell's nucleus will start out as a band and turn into a horseshoe shaped one with lumps. As a person starts to fight off an infection you will see many hyper-segmented (old) WBC's. However, if the person has been fighting off the infection for a long time then you will see more one segmented youth cells because the infection has taken all the older cells. I refer to as like a war. When the war starts out the older people fight. After all the old are gone then you have no choice but to use the younger and younger people until all is gone. That is a shift to the left which is a poor prognosis. A shift to the right is indicating recovery.
How old was Gram in Freak the Mighty?
Gram was about 70-80 years old in Freak the Mighty
