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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Brock Biology of Microorganisms (14th Edition)
- 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_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_forwardWhat 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_forward
- r^2=6Dt , where D is the diffusion coefficient of thediffusing object and t is the time that the object is allowed to diffuse. If the diffusion coefficient, D, of a small protein is 5 x 10^-10 m2 s-1, how long (on average) does ittake for the protein to diffuse across a parasitic wasp that is 189 um long ?arrow_forwardIf the diameter of the field of view in your microscope is 2 mm under low power, and one Bacillus cell is 2 µm long, how many Bacillus cells would it take to reach all the way across this field of view? If yeast cells measure 10 µm in length, how many yeast cells would it take to reach across this same field of view?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
- Consider 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_forwardComplete the analogy Peroxidase: Haem :: Carboxypeptidase: Zn2+ Fe2+ Ca2+ Cu2+arrow_forward
- When the yeast cells have completely re-hydrated, measure out 1.8 mL of well-mixed yeast suspension (0.2% yeast) into each of two new 15 mL centrifuge tubes. Add 200 μL of a 10% (w/v) Sodium Azide*** in YGM solution to one of the 15 mL tubes with yeast suspension. Add 200 μl of YGM to the other 15 mL tube of yeast suspension for your Control. Let both tubes incubate at room temperature for 30 min, vortexing every ~5 minutes What is the % concentration of azide in this sample during metabolic inhibition?What is the % concentration of yeast in this sample during metabolic inhibition?arrow_forwardMeasure the length of Cell X using the ruler in Microsoft Word. Assuming the actual length to be 3 um, calculate the magnification. Show your complete solution. Based on Figure 1, what internal organization can be distinguished in cell X? Why? Based in Figure 1, can you see a limiting membrane? Can you deduce its presence? Why or why not? Figure 2 is an electron micrograph of the same type of bacterium as shown in Figure 1. The picture has been obtained by cutting a very thin section of the bacterial cell along its longitudinal axis. Measure the total length of the cell, and assuming the actual length to be 2.1 um, calculate the magnification. With reference with Figure 2, what are the major differences between the inclusions found in Figure 1 and the way they appear in Figure 2? What other structural features can be resolved?arrow_forwardCan 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_forward