List three technical reasons that a normal gram-negative cell might stain as if it were gram-positive. For each, explain the reason that this result would be observed.
Gram positive and gram negative staining techniques
Gram staining differentiate between gram positive and gram negative bacteria according to the thickness of peptidoglycan layer in the cell membrane.`Gram positive bacteria retains crystal violet while gram negative not.After decolourization it will take the color of counter stain.
Technical reasons are there in which normal gram-negative cell might stain as gram-positive.
- Use of old cultures
Gram staining works better with cells from cultures that are in the exponential phase of growth. Otherwise the culture may contain dead or ruptured cells. This will give confusing results.
- Longer decolourization
there are two possibilities. 1) If decolourization process carried out for more than 30s 2) if Ethanol wash was not done properly (there is a chance of the smear is too thick)
This may decolourize gram positive cells and give it as gram negative cells.
- Time of heat fixation
If heating the smear for fixation is done for more time the cells may rupture and give false results.
- And also washing and drying of the smear should be done properly.
Otherwise the water will dilute stains and result in false results,
List three technical reasons that a normal gram-negative cell might stain as if it were gram-positive....
A) You perform a gram stain on an unknown and two controls. The gram positive control organism appears pink when you observe it microscopically. Your unknown organism also appears pink. Is your unknown organism gram positive, gram negative, or can't tell? B) what is the reason you could have the above result?
5. You use the Gram stain to try to differentiate bacteria in a sample. You find that all of the cells are Gram negative, but the teaching assistant insists there are both Gram positive and Gram negative cells present in the sample you are given. You definitely smeared a loop of the sample onto the slide and your fingers are stained a little purple and also a little red from handling the sides of the slide. Give a reason why...
QUESTIONS Predict the effect on Gram-positive and Gram-negative cells of the following mistakes made when performing a Grum stain. Consider cac mistake independently a. Failure to add the iodine. b. Failure to apply the decoloriser. 3 c. Failure to apply the safranin. d. Reversal of crystal violet and safranin stains. Both crystal violet and safranin are basic stains and may be used to do simple stairs on Gram-positive and Gram-negative cells. This being the case, explain how they end up...
Describe the structure of gram-positive and gram-negative cell walls and explain their differences.
0/1 pts Incorrect Question 8 You have a mixture of gram positive and gram negative cells in culture. You prepare a slide from the culture and gram stain it, but when observing the sample using oil immersion, all cells appear purple. What is the likely technical reason why only purple- colored cells are observ ed? you forgot the mordant step O you killed the cells during heat fixation you forgot the decolorization step you forgot to add immersion oi
An antiseptic such as 70% alcohol dissolves lipids. It was observed that Gram-positive bacteria were more resistant to alcohol than Gram-negative bacteria. Is this an expected result? Why or why not, explain in detail.
SWAU u sulide of the slide Questions 1. What color are Gram-positive cells supposed to be after a Gram-stain? What about Gram-negative cells? (2 pts.) a rum + - purple Gram -- pink 2. What characteristics can be determined in a Gram-stain? (2 pts) 3. List all of the things that can go happen during the Gram-staining process that could lead to an incorrect or poor result. (2pts.) 4. Why are direct gram stains ordered on clinical specimens? (2pts.) 5....
Create a list of gram-positive and gram-negative bacteria in human diseases. Each reply should contain at least 3 of each, and briefly describe disease symptoms. please include the references
A Gram stain of unknown bacterium A grown for 24 hours show purple cells. Is bacterium A Gram positive or Gram negative? A gram stain of bacterium A grown for 72 hours shows both purple and pink stained cells. Additional analysis shows that bacterium A is NOT contaminated. Explain these results. You are given 2 nutrient broth tubes each containing a pure culture of one of two Gram positive bacteria. Unfortunately, the labels have washed off and you are asked...
QUESTIONS 1) Are acid fast cells gram positive or gram negative? Explain why it might be difficult to determine the Gram reaction of acid fast cells. 2) What is the significance of the mycolic acid layer in the following contexts? A) To bacteria for survival and infection B) During the acid fast staining procedure QUESTIONS 1) What is the difference between a pure culture and a pure colony? Is a streaking for isolation plate a pure culture when your original...