Tuesday, 3 June 2014

Day 1 Questions

First Day

- What did you do today?
     - Briefly describe your day's activities

Today, at the lab, we had a briefing about lab safety to let us know the importance of taking precaution when going about our practical work. After which, we started on our experiment. Firstly, after wearing our lab coats and gloves, we sprayed our work desk and hands with 70% ethanol before beginning the experiment. Then, we divided the agar dishes into two parts, marking out which side of the agar we would apply the samples on. After that, we lighted the alcohol burner to begin the experiment. Following that, we used sterile disposable inoculating loops to transfer the samples onto the agar. We dipped the inoculating loop into the sample before drawing a zig-zag line on the marked out half of the agar dish. Lastly, we sealed the agar dishes with parafilm before putting it in the incubator.

- What did you learn today?
     - Discuss any learning points from today's activities

Today, I learnt about the different characteristics of bacteria and also the importance of lab safety and how to use some new lab equipment. In the briefing that was given by Dr. Professor Chen, I learnt that bacteria can survive in very harsh conditions, ranging from places like the extreme cold to places like hot lava at boiling temperatures. I also learnt some new fun facts of bacteria like there are 20x more bacteria on the mobile phone than a toilet seat. Also, there were some new lab equipment such as the inoculating loop and the alcohol burner that I learned to use.

- How do you feel about today's activities?
     - Describe how the project has affected your understanding of the discipline and how it may be applied elsewhere
     - Share your insights for the day 

This project has affected my understanding of the discipline as I learnt about a very important insight - that not all bacteria are harmful. Initially, I thought that all bacteria were harmful. Now that I know that some bacteria are not harmful and are actually beneficial to us, I can apply it in my daily life by consuming more of these beneficial bacteria to ensure my personal and others' well-being. 

- What are bacteria? List down some characteristics of bacteria.

  • Bacteria are one of the oldest and first life forms on earth, they are prokaryotic microorganisms and they live in very extreme conditions such as acidic hot springs and radioactive waste. 
  • Some characteristics of bacteria include that they are prokaryotic, are unicellular, have cell wall made of peptidoglycan, are typically a few micrometers in length and vary in the shapes that they are formed, ranging from spheres to rods and spirals. 

- How can bacteria be identified?

Gram Staining: This technique is named after a pioneering Danish microbiologist. It works as follows.
1. The bacteria are stained with a purple dye (Crystal Violet). Most bacteria are then stained red.
2. The bacteria are stained again with Potassium Iodide.
3. The bacteria are then washed with alcohol. Those bacteria that retain the dye after washing are known as Gram Positive bacteria. Those that lose the dye are known as Gram Negative bacteria.
4. The bacteria are further stained with a pink dye (Safranin). Gram Negativebacteria will go pink after this dyeing, whereas Gram Positive bacteria will remain purple, from the original purple dye.

Ziehl-Neelsen Staining: This technique is also referred to as acid-fast staining. This technique is necessary because some bacteria, notably all Mycobacteria, have waxy coats on their cell walls that prevent them taking in the dye from the Gram Stainingprocedure. As a part of the acid-fast staining process, detergents are applied which remove this waxy coat.
1. The bacteria are stained with hot Carbol-Fuchsin, a red dye which contains detergents. All bacteria are then stained red.
2. The bacteria are washed with acid alcohol. Those bacteria that retain the red dye are known as acid-fast bacteria.
3. The bacteria are then stained with Methylene Blue, a blue dye. Those bacteria that retain the red dye from the original stain are known as acid-fast bacteria, all others go blue.
All Mycobacteria test positive using the Ziehl-Neelsen acid-fast stain test, i.e. all species of Mycobacteria stain red using this procedure. Thus, this procedure cannot be used to differentiate between species of Mycobacteria.  

- Name three common bacteria and places where they are commonly found.

  • Salmonella: a genus of rod-shaped, Gram-negative bacteria commonly found in food. It causes food poisoning.
  • Escherichia Coli (E. Coli): a gram-negative, facultatively anaerobic, rod-shaped bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms. 
  • Vibrio Cholerae: found in contaminated water and food. Causes cholera.  

- Are all bacteria harmful? If not, name some bacteria beneficial to humans. 

No, Lactobacillus rhamnosus has proven beneficial affects on intestinal immunity, L. acidophilus is one of the most common and versatile probiotics on the market, frequently used in yogurt cultures and hundreds of subspecies and strains have been developed and Lactobacillus casei Shirota which is commonly found in Yakult and aids in our digestion.


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