05-12-2012, 01:07 PM
RECOMBINANT DNA TECHNOLOGY & ITS APPLICATION
RECOMBINANT DNA.pptx (Size: 403.84 KB / Downloads: 38)
INTRODUCTION
A DNA molecule which is constructed by joining segments of two or more different DNA molecules with the help of some enzyme is known as RECOMBINANT DNA.
Under certain conditions, a recombinant DNA molecule can enter a cell and replicate there, either on its own or after it has been integrated into a chromosome.
This process is known as RECOMBINANT DNA TECHNOLOGY.
ISOLATION OF A SPECIFIC DNA
To isolate a gene or a specific DNA segment we must extract the cell’s DNA.
This DNA is cleaved with a Restriction Enzyme (obtained from some bacteria where they act as defense mechanism against viruses).
The most useful restriction enzymes make staggered cuts; that is, they leave a single-stranded overhang (sticky end) at the site of cleavage.
These overhangs are very useful in preparing recombinant DNA because the unpaired nucleotides will pair with other overhangs of a vector.
PREPARATION OF RECOMBINANT DNA
Cutted vector DNA and donor DNA with complementary bases are annealed.
Though the complementary bases are paired, the sugar-phosphate backbone of two DNAs has not been sealed yet.
An enzyme called DNA ligase seals the DNA segments to form a continuous and stable double helix of recombinant DNA.