Explain the sequence of events occuring in DNA replication
Narrate in a very short
During DNA replication, several events occur in a sequential manner. First, an enzyme called helicase unwinds and separates the DNA double helix by breaking the hydrogen bonds between the nucleotide bases. This creates a replication fork.
Next, another enzyme called DNA polymerase attaches to the separated strands at the replication fork. DNA polymerase moves along the parent strand in the 3' to 5' direction, synthesizing a new complementary strand in the 5' to 3' direction. The parent strand serves as a template for the formation of the new strand.
As DNA polymerase moves along the parent strand, it adds nucleotides to the growing new strand according to the base pairing rules (A with T, C with G). Adenine pairs with thymine, and cytosine pairs with guanine.
There are two parent strands at the replication fork, one is oriented in the 3' to 5' direction (leading strand) and the other is oriented in the 5' to 3' direction (lagging strand). The leading strand is synthesized continuously, while the lagging strand is synthesized in short fragments called Okazaki fragments.
The enzyme DNA ligase then joins these Okazaki fragments to form a complete complementary strand. Finally, two identical DNA molecules are formed, each with one new strand and one original parent strand. This process ensures the accurate replication of genetic information.
1. The DNA helix unwinds and separates into two strands.
2. An enzyme called helicase breaks the hydrogen bonds holding the two strands together.
3. Single-stranded binding proteins keep the separated DNA strands from re-forming a double helix.
4. The enzyme primase synthesizes RNA primers on the DNA strands.
5. DNA polymerase enzymes begin adding nucleotides to the RNA primers, creating new DNA strands in a 5' to 3' direction.
6. One DNA strand, known as the leading strand, is elongated continuously in the 5' to 3' direction.
7. The other DNA strand, called the lagging strand, is synthesized discontinuously as short Okazaki fragments in the 5' to 3' direction away from the replication fork.
8. DNA polymerase removes the RNA primers and replaces them with DNA nucleotides.
9. An enzyme called DNA ligase joins the Okazaki fragments and seals any gaps in the newly synthesized DNA strands.
10. The result is two identical DNA molecules, each consisting of one original and one newly synthesized strand.