Sunday, November 30, 2008

DNA Fingerprinting

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information. DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA ,Ribonucleic acid a type of molecule that consists of a long chain of nucleotide (Organic compounds that consist of three joined structures: a nitrogenous base, a sugar, and a phosphate group) unit, molecules.
The DNA alphabet is made up of four building blocks – A, C, T and G, called base pairs, which are linked together in long chains to spell out the genetic words, or genes, which tell our cells what to do. The order in which these 4 DNA letters are used determines the meaning (function) of the words, or genes, that they spell.

DNA fingerprints finger prints from 6 different people (1 in each column)
DNA can be cut into shorter pieces by enzymes called restriction endonucleases. The pieces can then be separated according to there size on a gel.
Human DNA is 99% identical between individuals, but the 1% that differs enables scientists to distinguish identity.

Tuesday, November 18, 2008

Blood groups

There are four main blood groups A, B, AB, O. Which are in the ABO blood grouping system. This blood typing system was discovered in 1901. The most common blood groups in this grouping system are A and O.
There is a Rh factor blood grouping system. Rh stands for rhesus. People have a so called Rh factor on the red blood cell's surface. This is also an antigen. People that have Rh antibodies naturally in the blood plasma are called Rh+. Those who haven't are called Rh-. A person with Rh- blood does not have Rh antibodies naturally in the blood. But a person with Rh- blood can develop Rh antibodies in the blood plasma if they receive blood from a person with Rh+ blood, whose Rh antigens can trigger the production of the Rh antibodies. A person with Rh+ blood can receive blood from a person with Rh- blood without any problems.
so you can belong to any of these blood types:
A Rh+
A Rh-
B Rh+
B Rh-
AB Rh+
AB Rh-
O Rh+
O Rh-
The rare Blood type Duffy-negative Blood, occurs much more frequently in people of African ancestry.

Saturday, November 15, 2008

Fingerprints

The first time fingerprint identification was used in the early 1900s in London. The fingerprint section of Scotland yard was set up by Sir Edward Henry. In 1902 Harry jackson became the first person to be convicted in Britain on fingerprint evidence. He was a burgular and left his fingerprint in wet paint at the scene of crime. Theese prints were patent prints.
There are different types of prints that can be found at a crime scene latent prints which are difficult to find and almost impossible to see. Also there are patent prints which are easy to see because they are left in substances such as dirt, paint or blood.
Each fingerprint has minutiae which are the small unique details of the fingerprint. A list of the minutiae in a fingerprint; ending ridge, island, dot, crease, short ridge and bifurcation which is the most common one looked for.
A fingerprint is made of ridge lines which form to make a special pattern. There are seven different types of pattern. The main three are arch, loop and whorl. Also there are tented arch, central pocket loop, double loop whorl and the accidental.



The arch:
The ridge lines flow across the finger and rise or wave in the center of the finger tip.
The tented arch:
Like the arch but rises sharply in the center.
The loop:
The ridges flow from one side of the finger curve into the middle of the finger curves round and exits the same side.
The central pocket loop:
Like the loop but has a circle in the center of the finger.
The whorl:
The ridges flow into a circle pattern.
The double loop whorl:
Two loops coming from opposite sides of the finger and meeting in the center.
The accidental:
A fingerprint that consists of a combination of two different fingerprint pattern types.
Fingerprints never change theygrow as we do. They grow back if the finger has been burned or scarred. Fingerprints are left because our bodies release water and oils through our skin. On some surfaces such glass prints show up easily.