Explain how the sequences of the newly created daughter DNA sequences compare to the original parent DNA sequence. And why do they look that way?
https://www.youtube.com/watch?v=NX9kwdQ3R6s
To understand how the sequences of newly created daughter DNA sequences compare to the original parent DNA sequence, we need to first understand DNA replication. DNA replication is the process by which a parent DNA molecule is copied to create two identical copies, known as daughter DNA molecules.
During DNA replication, the double-stranded parent DNA molecule unwinds and separates into two single strands. Each of these single strands serves as a template for the synthesis of a new complementary strand. The key principle underlying this process is base pairing - adenine (A) binds with thymine (T), and cytosine (C) binds with guanine (G).
As the new nucleotides bind to the parent template strand, a new complementary strand is formed for each single-stranded template. This means, in each daughter DNA molecule, one strand is newly synthesized (leading strand), and the other is synthesized in fragments (lagging strand).
Now, coming to the comparison between the daughter and parent DNA sequences:
1. The daughter DNA molecules are nearly identical to the parent DNA molecule. They contain the same four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
2. The sequence of nucleotides on the leading strand of the daughter DNA molecule is precisely the same as that of the parent DNA molecule that served as the template. This is because the leading strand is continuously synthesized in the same direction as the replication fork.
3. The sequence of nucleotides on the lagging strand of the daughter DNA molecule is also the same as that of the parent DNA molecule but with slight differences. This is because the lagging strand is synthesized in a discontinuous manner in Okazaki fragments. These fragments are later joined by an enzyme called DNA ligase. The small gaps, called Okazaki fragments, may cause slight differences between the parent and daughter DNA sequence on the lagging strand. However, these differences are minor and do not affect the overall genetic information.
In summary, with the exception of minor differences introduced during the synthesis of the lagging strand, the sequences of the newly created daughter DNA molecules are very similar to the original parent DNA sequence. This fidelity of replication ensures the accurate transmission of genetic information from one generation to the next.