ONE DROP OF BLOOD...... A Trace of Evidence

One drop of blood

                         Do you know that just one drop of blood is sufficient to convict someone of a crime. One drop of blood has enough DNA to identify a certain individual. A forensic scientist is an expert who analyses, identifies and interprets evidence connected with a crime. Aside from blood, a person's fingerprints or hair strand can be used to examine evidence from the scene of the crime. One of the newest techniques of analyzing identification evidence through a person's body samples is called DNA fingerprinting, also known as DNA profiling, is a technique to identify criminals through the analysis of the genetic material, DNA. With the exception of identical twins, the complete DNA profile of each individual is unique. The techniques based on the theory that it is extremely unlikely that two people would possess identical DNA.

                          DNA testing was originally developed for medical purposes in order to detect the presence of genetically inherited diseases. The technique is also used to settle paternity disputes -  that is, to determine the biological father of a child. The uses of DNA fingerprinting have expanded to include criminal investigation and forensic science. It was in 1987 that DNA fingerprinting was first used in criminal investigation in the United Kingdom. The most common type of DNA fingerprinting is called restriction fragment length polymorphism (RFLP). In order to obtain a DNA "fingerprint", DNA is first extracted from the body tissue and fluid, such as blood, hair strand or saliva. Technicians use a chemical called restriction enzyme to divide the DNA into fragments. The fragments are then separated according to the size by the laboratory technique called electrophoresis. The separated fragments form a pattern of dozens of parallel bonds that reflect the composition of the DNA. In principle, the pattern produced will always be the same for the same person. It is estimated that there are more than 10 billion possible patterns. Thus, many expert believe it is virtually impossible that the DNA pattern of one person would match that of another. Despite the controversy over the reliability of the method, it has become an accepted means of identification in courts. So the next time you brush your hair, think about it, you might be leaving traces of evidence behind.

OSMOSIS: A way of Preserving Food

                The term osmosis is sounds very technical at first encounter and may seem to have no practical in day to day living. But did you know that the concept of osmosis is being used by food manufacturers in the preservation of many foods? Even our mother uses it at home to preserve fruits and vegetables.

                The need to store food is important to humans for future consumption especially when food is in short supply. Preserving food is also important for food manufacturers to extend the food's shelf life. Unfortunately, microorganisms like bacteria, molds, and fungi attack stored foods causing food spoilage. The presence of moisture and warmer temperatures on stored foods are suitable conditions for microbes to grow. They absorb and utilize the substances found in the stored food for their growth.As a result, stored food attacked by these microorganisms produces undesirable taste and smell, changes color, and may cause stomach upset when eaten.

                 One way of preventing food spoilage is to store foods in strong salt solutions (brine) or in sugar solution (syrup). These solutions contain concentrated amounts of solutes (salts and sugar) and are hypertonic to the cytoplasm of microorganisms. Brine and syrup solutions can cause the removal of water from the cytoplasm resulting in dehydration  followed by death of the invading microbes. Such removal of water is involved in the process of osmosis. Pork, beef, and fish are some of the food stored in brine. Fruits are often preserved in syrup.

                  The principle behind longer shelf life of preserved food involves OSMOSIS....