Concept explainers
To calculate:
The time required by Escherichia coli
Concept introduction:
Flagella present in a bacteria are thin, long attachments that are fixed into the cell at one end and free at the other end. In Escherichia coli, peritrichous arrangement of flagella is observed. Most of the studies regarding
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EBK BROCK BIOLOGY OF MICROORGANISMS
- In a reproduction of an experiment famously performed by Louis Pasteur, you cultured yeast in the absence of oxygen (anaerobic growth) and measured (1) the rate of cell division, (2) the rate of glucose consumption, and (3) the intracellular ATP:ADP ratio. You then moved the cells to an incubator containing normal atmosphere (i.e., 21% oxygen), completed a second set of measurements, and made the following observations: The rate of cell division increased considerably after the addition of oxygen (aerobic growth) Glucose consumption dropped dramatically after the addition of oxygen Intracellular ATP:ADP ratios increased significantly (from 2:1 in the absence of oxygen to 10:1 in the presence of oxygen) Explain how the mitochondria in the yeast contribute to the dramatic drop in glucose utilization and increase in ATP concentrations in the presence of oxygen.arrow_forwardA clinical microbiologist is studying a microbe that can cause infections and gastrointestinal disease in humans, and which can also survive and reproduce in mice. A dormant cyst form of the microbe infects human hosts through fecal-oral transmission if they come in contact with mouse droppings and don’t wash their hands before eating. The organism grows in long filaments when grown at 20-28 deg C, and forms round/ovoid cells when grown at temperatures above 28 deg C. Sexual reproduction (fusion of haploid gametes) occurs in both humans and mice. A cell wall is present, and cells contain nuclei. This microbe could be which of the following? Bacterium Fungus Virus Protozoanarrow_forwardBacillis brevis are lysed using a valve-type homogenizer. The extent of disruption depends on the applied pressure and the number of passes through the homogenizer chamber and can be described by the equation, ln(1 − ?) = −????. Is Bacillis brevis a gram-positive or gram-negative bacterial cell? Based on this response, describe the cell wall structure and how it differs from the other type. Develop an equation for calculation of pressure as a function of the number of passes through the homogenizer. What factor(s) did you take into consideration when selecting the number of passes? Escherichia coli cells are lysed with the same homogenization, is this organism gram-positive or gram-negative? What impact does increasing the value of the constant, a, have on the required number of passes at a given pressure? What factors impact the value of a? If fine cell debris after homogenization makes subsequent solid-liquid separation difficult, what would you recommend? Answer as…arrow_forward
- What is the effect of salinity on the rates of photosynthesis versus respiration in Euglena gracilis as shown in Figure 2? What does the difference in the initial slopes of the curves in the left panel tell us?arrow_forwardplease choose correct letter and explain a bit 1. The strongest way by which a protein can maintain its shape is by using:a) ionic bonds b) disulfide bonds c) star war forces d) van der Waals forces 2. If a cell (like an amoeba) would be capable of migrating from one place to another only with movement created from the inside of the cell, then we can say that that movement is done mainly by: a) glycoproteins b) feet c) microtubules d) actin filaments True or False: In eukaryotic cells (such as human cells), the variety and diversity of proteins is much less than the variety and diversity of lipids.arrow_forwardI asked earlier a question, and I got this answer. Now, my question is: how do you get the 2.5cm= 100um? I have taken a picture of the paramecium in question, with the scale bar (100um), and a ruler showing it’s measurement is around 2.5cm. Is that how we got the 2.5?arrow_forward
- Imagine you repeated the counting of N. crassa conidial cells and found an average number of cells of 500. Before adding the cells to the hemocytometer, you mixed 100ul of conidial suspension with 100ul of water. You then added 10ul of this mix to the chamber. What is your density in cells/ml? O 10,000,000 cells/ml 2,500,000 cells/ml O 5,000,000 cells/ml O Impossible to determinearrow_forwardConsider a batch culture of sphere-shaped bacteria in a growth medium or broth, in which the mean cell diameter of the bacteria is 2.0 μm (micron). Show all your calculations and assumptions in answering the questions below: What is the volume of one of these sphere-shaped cells, expressed in liters? If there are 3 x 10^12 cells in one liter of this culture broth, what percentage of the volume is occupied by bacteria and what percentage is occupied by the cell culture broth (water only)? If the cells contain 80% water, what is the dry cell concentration, expressed as “grams dry weight/Liter of broth”? You should assume that the density of the cells dry mass is approximately 1.0 gr/cm3arrow_forwardThis is the growth curve for Clostirdium (incubated under optimal growth conditions). Use it to answer the following questions. 3 Cell concentration (million cells/ml) 2.5 2 0.2 1.5 1 0.5 0 2 The growth rate is lag log 0.25 4 0.32 0.5 units 6 million of cells per ml (Image description.: Horizontal axis is time in hours, Vertical is cell concentration in millions of cells per ml. Curve starts at 0,0, increases by 4 hours to 0.5 million cells/ml, goes up steeply over two hours from 0.5 million/ml at 4 hours to 2.5 million cells/ml at 8 hours, 8-12 hour shows an increase of 0.3 to 2,8 million cellls/ml and last 2 hours is flat at 2.8million cells/ml.) From 12 hr to 14 hr is called phase. lunar 2 8 Time (hours) 10 5 stationary 12 cells 14 death 16 million of cells per ml per hour hours million of cellsarrow_forward
- Can you please compute for the cells per mL of yeast suspension. Refer to the dataprovided below:Count in the 5 squares of the 1st chamber = 176Count in the 5 squares of the 2nd chamber = 134The dilution was 1:10.Formula: Bacterial count = (total count/Number of squares) (1/square volume)(dilution factor).arrow_forwardIf the number of cells in a bacterial culture rises by a factor of two in one generation, and n is the duration as determined by the formula in equation 1, N is the number of people in the group (2") No way ——- (1) (a) Calculate the number of cell divisions in 4 hours assuming the bacterial cell divides every 20 minutes under normal settings; (b) Calculate the number of cells generated after 4 hours assuming the bacterial cell divides every 20 minutes under standard conditions. (c) Under the same circumstances, how long will it take to make 8192 cells? (d) Calculate the hours if one bacterium cell divides every 30 minutes.arrow_forwardImagine you have been given a liquid culture of yeast with a starting concentration of 3.67 x 10' cells/ml and are asked to carry out the sample dilution process shown in the figure below. 100μl 100μl 100μl 100μl 100μl 0.9ml 0.9ml 0.9ml H2O H₂O 6.9ml 0.9ml H₂O H₂O H₂O Original 10-1 102 10-3 104 Culture 105 100μl 100μl 100μl Plate A Plate B Plate C a. How many colonies should have been present on Plate A in this example? - Answers must be whole numbers as partial colonies are not expected. b. Imagine you carried out the same dilution scheme shown in the figure above, but now, you do not know the concentration of the original culture. If you counted 163 colonies on Plate B, what is the concentration of cells/ml in the original culture?arrow_forward