BaRa2eT 2aLb
01-22-2009, 04:55 PM
التفاعل المتسلسل للبوليميرات
( Polymerase Chain Reaction )
The Polymerase chain reaction is a method for making many copies of a specific segment of DNA , starting with a very small amount .
This technique can be used to identify specific microorganisms from a small amount of DNA and to identify persons involved in crimes from DNA on Cigarettes in a single hair follicle .
The DNA to be amplified is mixed with deoxyribonucleotides , a thermal stable DNA polymerase called Taq Polymerase and DNA primers .
http://www.almohandes.org/vb/uploaded2/97910_1207321482.jpg
The mixture is heated to break the hydrogen bonds in the DNA , forming single- started molecules . The mixture is then cooled sufficiently to allow the DNA primers to anneal to each end of the segment to be copied .
http://www.almohandes.org/vb/uploaded2/97910_1207321569.jpg
Taq Polymerase then synthesizes the complementary strand of DNA , using yhe primer as the starting point .
http://www.almohandes.org/vb/uploaded2/97910_1207321610.jpg
The temperature is raised again to separate the DNA stands and then lowered sufficiently to allow the primers to attach . Taq Polymerase now synthesizes another set of new complementary strands .
http://www.almohandes.org/vb/uploaded2/97910_1207321675.jpg
This process is repeated until enough DNA has been produced to be identified or used for further research . After twenty-one cycles , one molecules of DNA can be amplified to over a million copies .
This amount of amplification can be achieved by running the reaction overnite in a thermal cycle , an instrument that automatically raises and lowers the temperature at appropriate time intervals .
http://www.almohandes.org/vb/uploaded2/97910_1207321705.jpg
( Polymerase Chain Reaction )
The Polymerase chain reaction is a method for making many copies of a specific segment of DNA , starting with a very small amount .
This technique can be used to identify specific microorganisms from a small amount of DNA and to identify persons involved in crimes from DNA on Cigarettes in a single hair follicle .
The DNA to be amplified is mixed with deoxyribonucleotides , a thermal stable DNA polymerase called Taq Polymerase and DNA primers .
http://www.almohandes.org/vb/uploaded2/97910_1207321482.jpg
The mixture is heated to break the hydrogen bonds in the DNA , forming single- started molecules . The mixture is then cooled sufficiently to allow the DNA primers to anneal to each end of the segment to be copied .
http://www.almohandes.org/vb/uploaded2/97910_1207321569.jpg
Taq Polymerase then synthesizes the complementary strand of DNA , using yhe primer as the starting point .
http://www.almohandes.org/vb/uploaded2/97910_1207321610.jpg
The temperature is raised again to separate the DNA stands and then lowered sufficiently to allow the primers to attach . Taq Polymerase now synthesizes another set of new complementary strands .
http://www.almohandes.org/vb/uploaded2/97910_1207321675.jpg
This process is repeated until enough DNA has been produced to be identified or used for further research . After twenty-one cycles , one molecules of DNA can be amplified to over a million copies .
This amount of amplification can be achieved by running the reaction overnite in a thermal cycle , an instrument that automatically raises and lowers the temperature at appropriate time intervals .
http://www.almohandes.org/vb/uploaded2/97910_1207321705.jpg