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