Bacteria

Gram  positive and Gram negative bacteria cell wall

 

The most significant difference as we can see from the picture above is the thickness of peptidoglycan layer! Gram positive bacteria has thicker peptidoglycan cell wall than gram negative bacteria. Peptidoglycan is mainly a polysaccharide composed of two chemical subunits. These subunits are N-acetylglucosamine and N-acetylmuramic acid. In some organism, adjacent layers of peptidoglycan are formed through cross-linked of short chains peptides by transpeptidase enzyme, resulting shape and rigidity of cell wall. Besides, in gram negative bacteria, they got beta lactamase enzyme found in porin to digest beta lactam ring on antibiotics and this is why makes them virulent in our body.

 

Normally bacteria with cell wall cannot change its shape. Only mycoplasma, the smallest bacteria can regularly change their shape. Dr also emphasized that observe microscopically means using microscope while observe macroscopically means observe using naked eye. In metabolism, one of the important features is intermediate. Examples of intermediate is pyruvic acid. It act as precursor or electron carrier between glycolysis and kreb's cycle. On the other hand, gram negative bacteria will cell walls is more abundant than gram positive bacteria. Basically it is divided into two groups: Nonphototrophic (do not use light as source of energy and carbon dioxide as carbon source) and phototrophic(oxygenic and anoxygenic).

 

In enteric group, Proteus mirabilis is the most common agent in Urinary Tract Infection. Salmonella cause serious dysentery which is blood diarrhoea than E. coli. Endoscopy is the method of inserting camera into stomach to determine the presence of ulcer. Dr also mentioned that there is a hook at the end to pick up sample for further diagnosis. Lastly, I only realised that Helicobacter pylori only cause ulcer in stomach but not mouth! I was quite shocked as for this while I was thinking this is the cause of ulcer in mouth. :X

 

 

First Chapter of Second Semester.

It's the end of mid semester break and here I am writing my blog. I have changed to update here in blogger as there were some problems in the previous website that I was using. From the beginning of semester till mid semester, we have learned two chapters in microbiology II. The first chapter: Nomenclature and classification of microorganism and the second chapter: Introduction to immunology.
So, let's kick start with the first chapter! Actually I believe all of us are quite familiar with this topic as we learned this before in first semester. However after the first exam basically we have given all the knowledge back to lecture. And it's time to revise and get into details. During lectures by Dr Siow, she had given us a lot of extra information that is not found in notes. For example, she told us one of the example of culture collection bank called ATCC (American type culture collection). Let say Bacillus subtilis is deposited in ATCC, then at the back of the name there will be the code. Example: Bacillus subtilis ( ATCC 007). Anyone can purchase the bacteria deposited in culture collection bank. Besides, we have also learned about small permanent genetic difference differentiates species into strain . The first strain studied is known as type strain. We can identify whether the bacteria is a type strain by looking at the presence of small transcript T at the end of the code. Also, the details of how 16s rRNA identification can be carried out including elongation of primer, agarose gel electrophoresis and send for sequencing in data base. One of our assignment is to create our own mind map on this chapter and this is the one I did.

It is the summary of chapter one and now we proceeds to chapter 2!

Veron said during her form 6 she already learned very detail about the process in immunology and it is quite complicated. I did not learn very deep into this topic in matriculation so I think I will just have to be very concentrate on the lectures! Like Dr Siow said, immunology is like a snowball rolling from the slope. It will get bigger and bigger as it rolls to the end which same goes to this topic, the process or chemical reactions will be more and more. At the end you will realise they are all connected from the beginning of lectures until the end of lectures. Once you missed any lectures, it will be difficult for you to understand the following one as they are inter-related .

 The following are the simplified notes that I have made for the beginning of immunology.

Below is the overall picture that we drawn on the white board!

Dr Siow sometimes will ask few of us to draw the phagocytosis process by macrophage start fom the infection site until the approaches of T cells and B cells. As the learning goes on, so as the process. The dendritic cell and production of antibodies appears at last. With a clearer picture, we realised that all the process are actually connected and influenced each other as well. We might learn inflammation at the beginning of lecture, but at the end it is happening at the same time during phagocytosis. All the reactions happen simultaneously and it does not mean that one reaction happen after another. As a conclusion, in order for us to understand immunology, we should draw it out and link all process together using arrow so that we can know which affects which. Also, we need to know what are the proteins that are located at every cells. For example,
T cells - Tcr, fas-ligand
Infected living cells- fas, MHC class I
B cells- MHC class II, immunoglobulin
Macrophage- MHC class II
Dendritic cell- MHC class II

I wish this snow ball will remain it's size and does not melt as time goes on. :D