Microbiology. Please answer original forum with a minimum of 250 words

respond  student with a minimum of 100 words separately

please follow directions or I will dispute

original forum

Methods to preserve our foods has been a problem of mankind since we settled into groups and began to store our foods to eat at later times. As we stored our food to eat later, mankind often came back to collect his food only to find that microbes, which are ever-present, had already eaten it.

We know about expiration dates on foods and by now in the class, we understand that with microbes, it is a race between how fast one species grows against another. We eat the food before the microbes grow beyond a certain point (spoil the food with their waste by-products).

Some foods store for longer than others and depending on natural and some less than natural processes, we can extend the amount of time a food can be kept before microbes will take over and spoil the product. Keeping produce fresh for long periods of time has been a problem since one cannot treat fresh fruits and vegetables without altering the taste and texture.

A new and somewhat controversial method of food preservation, particularly produce, is gamma irradiation. This method uses high energy gamma radiation to treat food and has shown great promise in extending the shelf-life. Gamma irradiation is approved for use and does not show any ill effect on the produce itself.

Proponents of gamma irradiation claim that the method is safe, extends shelf life, and leaves no residue or otherwise dangerous chemicals on produce. Opponents argue the use of gamma irradiation is not safe, the facilities where produce is treated is not the proper place for this type of radiation to be released and exposure of the workers is likely.

Review Chapters 8 and 12 of your textbook on Microbial Metabolism and Modern Applications

Review these facts from the FDA on Food Irradiation

In this forum, choose a side; pro or con for gamma irradiated food. Choose to defend the use of gamma radiation as safe to use and safe to consume foods. OR, choose to oppose the use and consumption of foods treated in this manner.

Topic 1: Pro Gamma Irradiation of Food

Topic 2: Against Gamma Irradiation of Food

Address the following questions;

-Would you eat gamma-irradiated strawberries?

-Gamma-irradiation does extend the shelf-life but after some time, mold does begin to grow. Where does the mold come from?

-Was the mold already present on the strawberries and the growth slowed by the gamma irradiation?

-If gamma irradiation becomes the standard for processing produce, over time will the constant radiation exposure select for resistant strains of microbes that will eventually be able to grow despite gamma radiation? Why or why not?

-What about agricultural workers safety? Who is looking out for the women and men responsible for gamma irradiation of produce?

________________________________

Student Response

kyle

I am against gamma irradiation for foods even if it prolongs the shelf life of the food. We have so many altered and genetically modified food in our grocery stores it seems like gamma irradiation is the next step for food to become less natural and more modified. While it slows down the process of spoiling it also makes the food less nutritious. It kills the bad bacteria but also damages the fruit or vegetable as a whole. It’s like putting hydrogen peroxide on a wound. You may think it’s doing a good job by killing all the bacteria in your wound but it’s also killing all the good bacteria helping to fight against infection. So no, I will not eat a gamma-irradiated strawberry. Mold can still be present in the food because the radiation only kills most of the bacteria. After a while, the bacteria that wasn’t killed begins to grow and causes the food to spoil and rot. Gamma irradiation is supposed to kill the bacteria so if mold had begun to grow it would just stop it in whatever stage it was in. In the long run, a lot of scientists fear that the more gamma irradiation is done that the bacteria will begin to morph. Just like superbugs that we talked about a few weeks ago. The more you try to stop something the more chances it has at evolving and becoming resistant to the irradiation. Another large concern is the workers. Prolonged studies will have to be done to see if overexposure caused any damage, but it seems like an easy fix to just not be exposed. There is a long history of people being exposed to things that “experts” said was not harmful and ended up giving them cancer. It seems like an easy fix to just eat our food fresh and if we can’t then find food that has a longer shelf life without modifying it.

Center for Food Safety and Applied Nutrition. (n.d.). Consumers – Food Irradiation: What You Need to Know. Retrieved from https://www.fda.gov/food/resourcesforyou/consumers/ucm261680.htm

Christy

It’s good to look at both sides of this topic. Most of us have been consuming gamma irradiated foods and may not realize it. This type of food preservation technique has been in used widespread for more than fifty years. The good thing is that gamma irradiation is considered safe for the food it treats since it’s only the energy from the radiation that is treating the microbial growth and not the source of the radiation itself. For those who are proponents, they point out that it’s a cleaner-type of treatment for delicate produce since it’s likely been less-treated with other chemical inhibitors after gamma irradiation because it does not need further treatment.

Many are concerned about what’s on what they eat and are concerned that gamma radiation alters nutrient content (Maraei and Khaled, 2017). Presumably, gamma irradiated produce should be cleaner in terms of fewer pesticides. Would there be a way to test this to see if gamma irradiated produce has fewer chemicals than non-gamma irradiated produce?

Enjoy your day, Dr. Franklin

References

Maraei, Rabab and Elsawy, Khaled. (2017). Chemical Quality and Nutrient Composition of Strawberry Fruits Treated by Gamma Radiation.Journal of Radiation Research and Applied Sciences, Vol. 10, Iss. 1, 2017.

Microbiology

 

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Solutions, Acids And Bases Lab Report. BIOL 102: Lab 2

Solutions, Acids and Bases

PRE-LAB ASSIGNMENT:

Students are expected to read pages 1 to 3 before coming to the lab to complete the experiments.

Print this entire lab packet and bring it to the laboratory. You must submit the completed lab worksheet for credit. Please provide a FULL lab report for this experiment.

Objectives:

After completing this laboratory assignment, students will be able to:

· Measure the pH of various liquids.

· Demonstrate that buffers stabilize the pH of a liquid.

· Measure the ability of commercial antacids to buffer the pH of a liquid.

Acids:

Acids are ionic compounds (compounds with a positive or negative charge) that break apart in water to form hydrogen ions (H+). The strength of an acid is based on the concentration of H+ in the solution.

The greater the concentration of H+, the stronger the acid.

1

1

1

Characteristics of Acids:

· Acids taste sour.

· Acids react strongly with metals (Zn + HCl).

· Strong acids are dangerous and can burn your skin.

Examples of Acids:

· Vinegar

· Stomach Acid (HCl)

· Citrus Fruits

Bases:

Figure 1: Hydrochloric acid (HCl) in water

Bases are ionic compounds that break apart to form a negatively charged hydroxide ion (OH-) in water. The strength of a base is determined by the concentration of hydroxide ions (OH-). The greater the concentration of OH-, the stronger the base. Solutions containing bases are often called alkaline .

Characteristics of Bases:

· Bases taste bitter.

· Bases feel slippery.

· Strong bases are very dangerous and can burn your skin.

Examples of Bases:

· Sodium hydroxide (lye)

· Ammonia

Figure 2: Sodium

Hydroxide (NaOH) in water

pH Scale and Indicators
The strength of an acid or a base in a solution is measured on a pH scale. The pH scale is a measure of the hydrogen ion (H+) concentration. It spans from 0 to 14 with the middle point (pH 7) being neutral (neither acidic nor basic). Any pH number greater than 7 is considered a base and any pH number less than 7 is considered an acid. 0 is the strongest acid and 14 is the strongest base. An indicator is a special type of compound that changes color as the pH of a solution changes, thus telling us the pH of the solution.

Figure 3: A pH scale indicating the pH of common substances.

Measuring pH
A convenient way of measuring the pH of a solution is with pH paper. pH paper is treated with a chemical indicator that changes color depending on the concentration of H+ in the solution that it has contacted. The color chart on the container of the pH paper is used to compare the color of the pH paper to determine the pH of the solution (see Table 1).

Table 1: Examples of pH indicators.

Indicator

Range

Color Change

Methyl violet

0.2 – 3.0

Yellow to blue-violet

Bromphenol blue

3.0 – 4.6

Yellow to blue

Methyl red

4.4 – 6.2

Red to yellow

Litmus

4.5 – 8.3

Red to blue

Bromcresol purple

5.2 – 6.8

Yellow to purple

Phenol red

6.8 – 8.0

Yellow to red

Thymol blue

8.0 – 9.6

Yellow to blue

Phenolphthalein

8.3 – 10.0

Colorless to red

Buffers
Buffers are mixtures of two chemicals that stabilize the pH of a solution by resisting changes in the pH.

· If the pH is too low, one chemical will bind some of the hydrogen ions and raise the pH.

· If the pH is too high, the other chemical will donate some hydrogen ions to lower the pH.

pH in the body
The blood pH must be maintained very close to 7.4 which is slightly alkaline. A change of 0.2 pH units in either direction is considered dangerous and potentially fatal. Hydrogen ions are extremely reactive and affects many molecules which regulate physiological processes.

The body regulates pH in several ways including eliminating CO2 by the lungs and eliminating other acids and bases by the kidneys. The most important way to minimize pH changes in the body is using buffers. All body fluids, inside or outside of the cells, have buffers which defend the body against pH changes. The most important buffer in extracellular fluids, including blood, is a mixture of carbon dioxide (CO2) and bicarbonate anion (HCO3). CO2 acts as an acid because it forms carbonic acid when it is dissolved in water and donates hydrogen ions when they are needed. HCO3 is a base, soaking up excess hydrogen ions. There are also other buffers in the blood, such as proteins and phosphates, but they are less important in maintaining the overall pH of the blood. Blood pH is established by a balance between bicarbonate and CO2.

LAB DATASHEET
Exercise 1: Determining the pH of common substances
1. Use pH paper to measure the pH of the following liquids.

2. Be as accurate as possible

3. Use a fresh piece of pH paper or pH dipstick for each test.

4. Record your data.

Baking soda

___7____________

0.1M HCl

___0____________

Vinegar

___2____________

Tap water

___6___________

Seltzer water

___5____________

Exercise 2: Testing the buffering capacities of various solutions
1. Obtain and label four test tubes according to the four solutions listed in Table 2.

2. Place 5 ml of each solution into its appropriately labeled tube.

3. Measure the pH of each of the solutions in the tubes and record these initial values in Table 2.

4. Add 5 drops of acid (0.1 M HCl) to the first tube. Cover the tube with parafilm and invert the tube gently to mix the contents.

5. Measure the pH of the acidified solution and record it in Table 2.

6. Repeat steps 4 and 5 for each of the remaining tubes. Record your results in Table 2.

7. Compare the initial pH and the pH after acid addition for each sample.

Table 2: Buffering Capacity Data

Solutions

Initial pH

Final pH (after HCl)

Comparison of pHs

Water

5

2

PH dropped by 3

0.1 M NaCl

5

3

PH dropped by 2

Skim milk

6

5

PH dropped by 1

0.1 M phosphate buffer

7

7

PH stayed the same

Analysis Questions:

1. What is the biological importance of using a buffer?

Buffers prevent changes in PH, and maintain balance.

2. Which of the solutions is the most effective buffer? Least effective?

The most effective buffer is the solution who’s PH changed less, (in this case will be 0.1M phosphate buffer). The least effective solution will have a significant change in PH (in this case it will be H2O with an original PH of 5, and a final PH of 2 after addition of 0.1M of HCL)

Exercise 3: Testing the effectiveness of commercial antacids and other products
Commercial antacids such as Alka Seltzer, Rolaids, and Tums claim to “neutralize stomach acid” by absorbing excess hydrogen ions (produced as hydrochloric acid in the stomach).

To test the abilities of these products to absorb acids, do the following:

1. Using a pipet or 10 mL graduated cylinder, add 1 ml of the antacid solution to a test tube.

2. Add 1 drop of the indicator Bromcresol purple to the tube.

3. Cover the tube with parafilm and invert the tube to mix the contents.

4. Add one drop of 0.1 M hydrochloric acid (HCl) to the tube; mix after each drop.

a. Continue this process until the solution turns yellow, indicating an acidic solution.

5. Record the number of drops of acid needed to generate the change of color.

a. This number of drops is an index to the amount of acid (H+) that the solution neutralizes before the pH drops below the yellow end-point of Bromcresol purple.

Table 3: Effectiveness of Antacids Data

Antacids

Drops of Acid

Alka – Seltzer

33

Rolaids

1

Tums

1

Analysis Questions:

1. Which antacid neutralizes the acid best? Which neutralizes the acid least?

Rolaids and Tums neutralized acid best while Alka-Seltzer neutralized acid the least.

2. Examine the package of the products you tested. What are the active ingredients of each product?

Tums – Calcium carbonate 50mg

Rolaids – Calcium Carbonate

Alka- Seltzer – Aspirin 325mg, citric acid 1000mg, and sodium bicarbonate 1916mg

Solutions, Acids And Bases Lab Report

 

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