Question

Explain the process of DNA replication, including what enzymes are involved. Compare this with Polymerase Chain Reaction and Sanger Sequencing.

Answer 1

Process of DNA replication:

DNA replication is the process in which the DNA of the cell makes a copy of itself during the process of cell division. There are several steps involved in this process. They are:

1. The initial step is the unzipping of the double helical structure of the DNA molecule.

2. This process of unzipping is aided by an enzyme which is called as the helicase. This enzyme helps in breaking the hydrogen bonds which hold the complimentary bases together.

3. This separation leads in the formation of a Y shaped structure. This structure is called as the replication fork. These two strands which are separated will act as a template to form the new strands of the DNA.

4. In these two strands one strand will orient from the 3' to 5' and the other will be in the 5' to 3' direction. The one from 3' to 5' is called as the leading strand where as the other one is called as the lagging strand. These two will replicate differently as their orientation is different.

5. A short piece of RNA which is called as a primer and lead by an enzyme primase comes to bind at the end of the leading strand. At the same time many RNA strands are prepared by this enzyme to join the lagging strands.

6. This DNA polymerase binds to the leading strand and then adds new complementary neucleotides. The same is repeated at the lagging strand but in short chunks which are called as the okazaki fragments.

7. In the leading strand the replication is called as the continuous where as in the lagging strand it is called as the discontinuous.

Polymerase Chain reaction:

This is a chain reaction which is generally used to create copies of specific DNA segments. This is the artificial process in which only the specific DNA segemnt can be generated. The process of replication is the process in which whole DNA is replicated naturally.

Sanger sequencing:

This is generally known as the chain termination method which is used for the determination of the nucleotide sequence of DNA. This is an applied bio systems techniques based on the selective chain termination techniques.