when dna replicates what happens to the chromosomes.?
When DNA replicates, the chromosomes undergo a specific process. To understand what happens to the chromosomes during replication, we need to first understand the basics of DNA replication.
DNA replication is the process by which a cell duplicates its DNA to produce two identical copies. This process occurs during the S phase of the cell cycle and is essential for cell division and ensuring genetic continuity.
Let's explore the steps involved in DNA replication:
1. Initiation: Replication is initiated at specific sites on the chromosomes called origins of replication. As the replication machinery assembles at these origins, the DNA double helix is unwound by enzymes, creating a replication fork.
2. Unwinding and separation: The double helix is further unwound and separated into two strands by an enzyme called DNA helicase. This creates a "Y" shape, with the unwound DNA strands as the two arms of the fork.
3. Base pairing and synthesis: Each unwound DNA strand serves as a template for the synthesis of a new complementary strand. The enzyme DNA polymerase adds nucleotides to the growing new strand in a specific order dictated by the complementary base pairing rule (A with T, and G with C).
4. Semiconservative replication: The resulting two DNA molecules each contain one original (parental) strand and one newly synthesized (daughter) strand. This is known as semiconservative replication. The two new DNA molecules are identical to each other and to the original DNA molecule.
Now, to answer the question, during DNA replication, the entire chromosome undergoes replication. Each chromosome consists of a single continuous DNA molecule, and this molecule is replicated to produce two identical copies. As a result, the original chromosome becomes two sister chromatids connected by a centromere, ready for cell division.
In summary, when DNA replicates, the chromosomes undergo a process where each chromosome is duplicated to form two identical copies, known as sister chromatids. These sister chromatids remain connected until cell division occurs.