1. You are given a 1 gram soil sample of unknown bacterial load. After doing 10-fold...
1. You are given a 1 gram soil sample of unknown bacterial
load. After doing 10-fold serial dilutions of the soil in sterile
water, 100 uL volumes are taken from each dilution for preparation
of pour plates. Following incubation, each half of the
10-8 plate has 46 colonies.
a) What was the dilution factor?
b) How many bacteria were present in the soil?
2. Staphylococcus aureus divides every
20 minutes. A culture begins with 10 bacterial
cells.
a) After 5 hours, how many generations have occurred
b) After 5 hours, how many bacteria are present?
3. How many milliliters would you need to prepare a 10-2 dilution from a 10ml starting culture?
Homework Answers
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1. You are given a 1 gram soil sample of unknown bacterial
load. After doing 10-fold...
You are given a 1 gram soil sample of unknown bacterial load. After doing 10-fold serial...
You are given a 1 gram soil sample of unknown bacterial load. After doing 10-fold serial dilutions of the soil in sterile water, 100 uL volumes are taken from each dilution for preparation of pour plates. Following incubation, each half of the 10-8 plate has 46 colonies. a) What was the dilution factor? b) How many bacteria were present in the soil?
17. A sample of a culture of bacteria is subjected to 10-fold serial dilution; 0.1 mL...
17. A sample of a culture of bacteria is subjected to 10-fold serial dilution; 0.1 mL aliquots of the dilutions are grown on agar plates and the number of colonies counted: Dilution: Number of colonies: 10- Too many to count 10-6 10- 2 0 -3 Too many 249 to count 10-4 24 2 10-5 0 BIOT 5021-SP2 Assuming that one cell gives rise to one colony, how many cells were there per mL of the original culture?
Hello, just wanted to check my answers. Answer as many as you like/can. Thankyou. 1) Four...
Hello, just wanted to check my answers. Answer as many as you like/can. Thankyou. 1) Four grams of soil are added to 36 ml sterile water and mixed well. 0.1 ml of this mix was added to 9.9 ml sterile water. This was diluted by 4 successive 1/10 dilutions. 1.0 ml from the last dilution was used to prepare a pour plate. After incubation 289 colonies were counted. Calculate the # CFU/g soil. 2) A 0.1 ml aliquot of a...
A culture of Staphylococcus is diluted as follows: (1) 20mL are added to 80mL of water....
A culture of Staphylococcus is diluted as follows: (1) 20mL are added to 80mL of water. (2) 10uL from (1) are then added to 9.99mL of water. (3) A 10-2 dilution is made from tube # (2). (4) 100uL from (3) are plated for a pour plate and incubated. There were 34 colonies counted on one quarter of the plate following incubation. a) What was the overall dilution? b) How many cfu/mL were present in the original culture? c) How many...
2) You are given a bacterial culture with the following serial dilutions: 1 ml 0.1 ml...
2) You are given a bacterial culture with the following serial dilutions: 1 ml 0.1 ml 1 ml Original culture 9 ml media 9.9 ml media 9 ml media B a) what is the final dilution in tube C? (1 pt) b) if you plated 100 ul of the bacterial dilution in tube B, incubated and counted 114 colonies the next day, what would the CFU/ml be of the original bacterial culture? (show work and units- 2 pts)
I need the answer to question D, thank you. Question 10. Bacterial density in a counting...
I need the answer to question D, thank you.
Question 10. Bacterial density in a counting chamber A scientist needs to calculate the density of a bacterial culture in order to set up an experiment, but the laboratory spectrophotometer is broken and the only alternative is to use a counting chamber that she finds in a drawer of old equipment. The counting chamber has a glass to coverslip height of 0.02 mm and the instructions say that each square of...
9. Suppose you ingest 20 cells of Salmonella typhimurium in a chicken taco. Some of the...
9. Suppose you ingest 20 cells of Salmonella typhimurium in a chicken taco. Some of the bacteria are killed as they pass through the stomach but 10 viable cells survive and reach the intestine. Suppose further that Salmonella generation time in the intestine is 2.7 hours and that you will feel sick when there are 1,000,000 bacteria. How much time will elapse before you feel sick? Show your work. 10. You are doing a viable cell count on a bacterial...
Example An otherwise typical bacterial cell increases from one cell to 256 cells in 10 hours....
Example An otherwise typical bacterial cell increases from one cell to 256 cells in 10 hours. What is the generation time of this organism? Example: Escherichia coli has a doubling time of 20 minutes. If there are 5 cells at the beginning of the experiment, how many will there be in 3 hours? Example You perform a serial dilution and determine that the original number of cells in your sample was 12,000. How many bacteria will be present in 12...
A. You have been given a tube of E. coli. You are asked to make 1...
A. You have been given a tube of E. coli. You are asked to make 1 mL total volume of 10-1 dilution of the bacterial culture. Explain how you would do this. Show all necessary calculations. ____ ml cells + _____ ml water = 1 ml (total volume) B. Next, you were asked to make a 10-2 dilution of the bacterial sample. Explain how you would perform this. Show all necessary calculations. You have bacteria at a concentration of 2...
I need the answer to quetion E, thank you. Question 10. Bacterial density in a counting...
I need the answer to quetion E, thank you.
Question 10. Bacterial density in a counting chamber A scientist needs to calculate the density of a bacterial culture in order to set up an experiment, but the laboratory spectrophotometer is broken and the only alternative is to use a counting chamber that she finds in a drawer of old equipment. The counting chamber has a glass to coverslip height of 0.02 mm and the instructions say that each square of...
17. A sample of a culture of bacteria is subjected to 10-fold serial dilution; 0.1 mL aliquots of the dilutions are grown on agar plates and the number of colonies counted: Dilution: Number of colonies: 10- Too many to count 10-6 10- 2 0 -3 Too many 249 to count 10-4 24 2 10-5 0 BIOT 5021-SP2 Assuming that one cell gives rise to one colony, how many cells were there per mL of the original culture?
2) You are given a bacterial culture with the following serial dilutions: 1 ml 0.1 ml 1 ml Original culture 9 ml media 9.9 ml media 9 ml media B a) what is the final dilution in tube C? (1 pt) b) if you plated 100 ul of the bacterial dilution in tube B, incubated and counted 114 colonies the next day, what would the CFU/ml be of the original bacterial culture? (show work and units- 2 pts)
I need the answer to question D, thank you.
Question 10. Bacterial density in a counting chamber A scientist needs to calculate the density of a bacterial culture in order to set up an experiment, but the laboratory spectrophotometer is broken and the only alternative is to use a counting chamber that she finds in a drawer of old equipment. The counting chamber has a glass to coverslip height of 0.02 mm and the instructions say that each square of...
9. Suppose you ingest 20 cells of Salmonella typhimurium in a chicken taco. Some of the bacteria are killed as they pass through the stomach but 10 viable cells survive and reach the intestine. Suppose further that Salmonella generation time in the intestine is 2.7 hours and that you will feel sick when there are 1,000,000 bacteria. How much time will elapse before you feel sick? Show your work. 10. You are doing a viable cell count on a bacterial...
Example An otherwise typical bacterial cell increases from one cell to 256 cells in 10 hours. What is the generation time of this organism? Example: Escherichia coli has a doubling time of 20 minutes. If there are 5 cells at the beginning of the experiment, how many will there be in 3 hours? Example You perform a serial dilution and determine that the original number of cells in your sample was 12,000. How many bacteria will be present in 12...
I need the answer to quetion E, thank you.
Question 10. Bacterial density in a counting chamber A scientist needs to calculate the density of a bacterial culture in order to set up an experiment, but the laboratory spectrophotometer is broken and the only alternative is to use a counting chamber that she finds in a drawer of old equipment. The counting chamber has a glass to coverslip height of 0.02 mm and the instructions say that each square of...
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