2014년 2월 25일 화요일

Endorphin


     It is unfortunate that the society shows no mercy to narcotics, but what if the human body secretes one that is about fifty times more potent than heroine? Endogenous Morphine, better known as Endorphin, is a peptide hormone mainly released from the pituitary gland located in the base of the brain. Endorphin is secreted when we are under severe stress, fear or pain. It helps us forget the pain and control our emotions by interacting with the receptors of the cells. In fact, endorphin is so potent that it doesn’t simply alleviate pain but literally makes us high-- How awesome is that? Particularly famous is a state known as ‘Runner’s high’ where an exhausted athlete suddenly experiences a feeling of euphoria due to endorphin release. Endorphin also helps mothers endure immense pain when giving birth. Scientists say that many near-death experiences those religious frauds always blab about may also be a product of endorphin release. No wonder that endorphin is released to its max when you’re dying.

     In those days when our biological ancestors lived in the wild, it was necessary that they withstand stress and pain following physically demanding tasks like running and hunting. Therefore a certain group of mutants that somehow happened to have Endorphin would have been able to survive better, leaving their awesome genetic trait to humanity. In short, it’s survival of the fittest all over again.   

2014년 2월 23일 일요일

Lactic Acid Fermentation

Kimchi
(Source: http://c.ask.nate.com/imgs/qrsi.php/11793224/21217261/0/1/A/17c782b771bb9b8a2768bbaebf4269ca.jpg)


     Unlike what many foreigners think, Kimchi actually has a sour taste. Kimchis that can be found in grocery stores of America are in many cases something what's called 'Raw-Kimchi', a type of Kimchi that hasn't fully undergone fermentation. Where does this sour taste come from? How is the process of fermentation related to Kimchi's unique sourness loved by many Koreans?

     Glycolysis, the first step of cell respiration in which a glucose (C6H12O6) splits into two pyruvates (C3H4O3), is anaerobic, meaning that it is capable of occurring without oxygen. Anaerobic respiration however undergoes a completely different path from that of aerobic respiration which eventually generates about 38 ATPs. Fermentation is one type of anaerobic respiration. Fermentation also generates certain amount of ATPs, 'recharging' the used up NAD+s to once again form NADH. In aerobic respiration, these NADHs can later on give up electrons to oxygen to eventually generate H2O. But in anaerobic respiration, as its name suggests, there exists no oxygen within the system that can accept electrons.
   
   (Source: http://blog.naver.com/dbok1234?Redirect=Log&logNo=110165450698)

Once again take a look at the chemical equation of anaerobic glycolysis:

C6H12O6 + 2NAD+ -> 2C3H4O3 + 2ATP + 2NADH + 2H+


Without O2, the 2NADH and 2H+ undergoes what's called lactic acid fermentation. A total of 4 H+s, two of which dissociated from NADH, attaches to two pyruvic acids (two each) to form lactic acid (C3H6O3). Lactic acid is what gives a sour flavor to fermented foods including Kimchi, cheese and yogurt. Making all this happen are lactic acid bacteria better known as lactobacillus. The presence of lactic acid Bacteria is crucial to fermentation. Without lactobacillus, A food would undergo putrefaction, or simply rot instead of fermentating.
(Source:  http://www.computescotland.com/acrylamide-offset-by-lactic-acid-bacteria-3652.php)