As your lab progresses you will begin to see growth appear on your agar. You wil
As your lab progresses you will begin to see growth appear on your agar. You will see smears where the growth is greater and also areas on the plate where it is less dense. aw "If you are in a public restroom and want the cleanest stall to go to the first one. Do not use the sanitizing hand dryer - you are just blowing the bacteria from around the room back on your hands; the cleanest spots in a restroom seem to be the toilet seat and the door knob (the two surfaces no one wants to touch)." "30% of women's purses have fecal matter on the bottom - so if you put your purse on the kitchen counter you may as well "poop" on it. Men's restrooms have 50% less bacteria than women's - so if possible only use the men's." Stand back men here we come. 🙂 Directions This will be an inquiry lab and you will write a formal lab report. ADDITIONAL INFORMATION......... It may take as long as three weeks for you to see growth. Remember that these microbial cells are so "tiny" that you need to magnify and stain them to see them. So it only makes sense that it will take multiple cell divisions so that the numbers will be great enough to see with the naked eye. Also, remember that temperature plays a role. If it is too hot you can kill them. If it is too cold they will divide slower....... be patient and you will be rewarded with "yuk" from what you thought was clean....... LAB DIRECTIONS Overview 1. Collect microbes from around your home. 2. Plate them. 3. Write a formal lab report using the directions I provide to you. Unit 8: Lesson 8 - Lab Response This will be an inquiry lab and you will write a formal lab report. You will think critically in your lab conclusion and analyze why you did or did not experience much growth as related to the environment in which you collected, or incubated, or stored your sample plates, or even which type of media you used. You will need at least one week or more to complete it. Here are the instructions to set up the lab and you will see the directions for how to write the lab report below them. You will put your lab report in the assignment box. You MUST use the lab form I posted in the Announcements so you can maximize your points earned. Complete your formal lab report and put it in the assignment box for lab 8. Materials you will need are lemon, strawberry, or cherry Jello (not sugar-free) sterile q-tips (swabs), 3 plastic cups or small glass bowls, and something to cover them with ie. saran wrap a loose-fitting glass lid, etc., Clorox or other disinfectants. LAB DIRECTIONS STEP BY STEP **Remember dry q-tips (swabs) for a wet surface and wet q-tips (swabs) for a dry surface. Try to find a location that is close to the warmest place in your home ie. on heating vent, behind fridge but not hot, for incubation. And remember you may be sampling pathogens. Use good lab protocol as seen in lesson 1 safety lab. **After collecting your samples cover the dish with plastic wrap so that you can view it without opening it. You want to be very careful with this plate as it may contain pathogenic mold or bacteria. Do not touch or inhale the growth. When you are finished documenting growth you can submerge the Jello with growth in a bleach solution to kill the microbes. Then dispose of it. 1. Prepare the Jello and use half the amount of water (you can also add a beef bouillon cube if you want, you might get more growth but it will be a darker color so you will not see the growth as easily). 2. Divide the Jello evenly between 3 containers and let it set until firm (you can always do more than 3 plates) 3. Use the sterile q-tips (swabs) and run them over surfaces of your choice to collect microbes (some options below). Remember wet and dry FYI for collection A few suggestions here *1. (refrigerator handle, *2. phone, *3. TV remote, *4. steering wheel etc. (your choice) *5. light switch plate cover *6. gas pump handle or gas cap cover If you do not have q-tips (swabs) you can *1. drop saliva (human and pet on different plates) or *2. cough or touch the Jello when it is set with dirty fingers, then use washed with soap fingers or fingers wiped with disinfecting wipe, or *3. drop a piece of used dental floss *4. or even make the plates the same but incubate in different areas; warmer is better - not hot, *5. you could also experiment with different agars/Jello. LEAVE ONE PLATE OF JELLO OR SECTION ON THE PLATE FOR A CONTROL. Your control does not contain microbes you collected 1. If you are checking temperature then you will leave the control at room temp, 2. if you are comparing hand washing then one section would be unwashed fingerprint, 3. if you are checking the countertop versus the toilet seat then one section would be without a bacterial swab sample. 4. You get the idea, the control is what stays the same and the variable is what you change. 4. After the Jell-o is set up wipe the q-tip (swab) across the Jello as if you are plating bacteria - see book for photos 5. Put the bowls somewhere safe away from humans and pets; do not eat it. You will need to cover it with a lid (preferably clear), or saran wrap that you can see through to check for growth but keep other airborne microbes out of the Jello. 6. Check for bacterial growth after 72 hours, then again in 24 hours, and keep checking. You should see growth within a week (sooner if it is warmer, longer if you have fewer or it is cooler), if not just keep checking. If you collect from an area with a lot of microbes you will see growth sooner as there will be more cells to divide and reproduce, thus more to see with the naked eye. With the human eye you will see visible bacterial colonies at 1 million cells- I had to take my plate to a window and slant it just right to see the texture and patterns etc. Natural daylight just seemed to work better for lighting. But the UV rays may also kill your growth so do not leave it to grow in a window. Remember that UV rays are often used to disinfect water (kill bacteria) in treatment facilities. Check daily so your plate does not become overgrown with bacterial colonies before you can compare them to the morphological chart. Dispose of the Jello and bacteria/mold after you have poured Clorox or some other disinfectant on it. Do not let children or pets eat or play with the Jello/agar - it is contaminated. How to write a formal lab report = 35 points Lab Report EXAMPLE " Don't Panic Here. I will provide a lot of feedback on each lab. Title ie. "Growing bacterial colonies on Jello/Agar plate" - do not use my example title 2 points Purpose: What is the reason for the experiment? This should include only one sentence. do not use my example purpose The purpose of this experiment is to demonstrate that bacterial growth can be found on multiple surfaces - do not use my example. 5 points Hypothesis: This is an educated statement and always includes an IF and THEN. This should include only one sentence if possible, and two if absolutely necessary. do not use my example IF the temperature of the environment is increased THEN the bacterial growth will be greater -do not use my example If hands are washed and scrubbed then there will not be as many bacteria found on their surfaces. -do not use my example 4 points Materials and Procedure: what did you use and how did you use it with enough clarity that someone else could follow your directions. 10 points Results: You can record on the chart I posted in Announcements. This is the data you collect. It could be numerical (quantitative) or anecdotal (qualitative) In other words ...... just the facts. You can include it in a chart, data table, or graph and add written paragraph form. But you only write or provide evidence of the results. This is "what occurred, NOT why it occurred". Provide all information and data and label it clearly. Most students lose points here because they do not label to ensure the graph etc. is understandable. On the chart you will include examples of morphology - whole colony shape, appearance margins, the size relative to container and size of the colony, elevation texture smooth or rough, appearance glistening shiny or dull, non-pigmentation cream or tan or white or pigmented purple red yellow- optical property opaque, translucent, transparent - etc. - may include a picture here 14 points Conclusion: This is the most important part of any lab report. This is where you think critically and analyze the material and information. This is where you explain WHY something happened. If you really don't know, you attempt to answer using scientific thought and include many vocabulary terms found in the text. For instance, you talk about why the washing of hands prevented bacterial growth, or why the temperature might have made a difference, or why different swabs (phone, light switch etc.) had different amounts or types of bacteria) REPEAT 2 Purpose of the Lab - scientifically correct, complete sentence, related to the lab. 5 Hypothesis - contains IF and THEN, scientifically correct, complete sentence, appropriate expected result 4 Materials and procedure - complete and easy to follow, allows the reader to understand set up and collection 10 Results - includes data clearly labeled and easy to follow 14 Conclusion - includes critical thinking about why (or why not) the results were seen, includes relevant vocabulary, uses lab form (morphological characteristics - See Announcements) provided to help guide the written report DIRECTIONS: COPY AND PASTE THE TEXT BELOW ONTO A WORD DOCUMENT IF YOU WANT TO USE FOR A LAB FORM OR YOU CAN USE LAB FORM POSTED IN ANNOUNCEMENTS. BUT YOUR LAB REPORT MUST BE IN FORMAL LAB FORMAT. FOR FULL CREDIT NO ESSAY Lesson 8 Lab Response-Bacterial Growth on Jell-O Medium LAB FORM See required chart in Announcements on lab form -Identification of Colony Morphology 0 pts Title - you name it here 2 pts Purpose of the Lab - scientifically correct statement, complete sentence, related to the lab. 5 pts Hypothesis – statement contains IF and THEN, scientifically correct, complete sentence, appropriate expected result 4 pts Materials and procedure – steps or process is/are complete and easy to follow, allows the reader to understand set up and collection 10 pts Results – describes what growth was seen, includes data clearly labeled and easy to follow *****The chart from Announcements goes here 14 pts Conclusion – specifically explains the lab and includes critical thinking about why (or why not) the results were seen, includes relevant vocabulary, and uses lab form (Lesson 8 Lab Form in Doc Share) provided to help guide the written report. *****Directions: Use the CHART FOUND IN ANNOUNCEMENTS AS AN ATTACHMENT......... to determine the morphological characteristics of the bacteria growth seen on your Jell-O medium; also include relative percentage size per container (ie. 25%, 50%, 75% coverage) Or add a photograph of your results AND IF THE ABOVE INFORMATION IS NOT ENOUGH BECAUSE SOMETIMES IT TAKES MORE THAN ONCE..................... HERE IS MORE Hypothesis: this is an if-then statement. Consider cause and effect. For instance, IF a happens THEN b will follow. Procedure: should be written so that another person can read what you did and replicate it. So if you skip steps here the other person or reader is at a loss as to what you did. Results: this is the data you collect. It may be qualitative (descriptive) and or quantitative (numerical) but must be presented logically so that the reader can follow your findings. You can use text to explain a chart that has information. Conclusion: this is the stickler in lab 8. Many of you put your results in your conclusion section. The numbers, data, and what you saw goes in results, not in conclusions. The conclusion is where you think about your results and then explain them thoroughly. So you could say my phone sampling showed the most growth because I take it everywhere.................this is just not enough of an explanation. You might instead say that the phone showed the most growth because you almost always have it with you. It sits out on your desk exposed to airborne microbes, it sits on bathroom sinks, while you wash your hands. You may be the only one using your phone but you probably do not wash your hands before you use it. You also probably have it out on public transportation. I doubt that many of you clean your phones as often as you clean your toilets or countertops. I am guessing that even if it is wiped often it is not disinfected. Some microbes can stay viable on a hard surface for hours or days and in some cases weeks. So your phone is exposed repeatedly.

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