DNA Replication Produces a Pair of Sister Chromatids Until Anaphase
Definition
DNA Replication
DNA replication is the biological process by which a cell copies its DNA to ensure that each daughter cell receives an identical set of genetic instructions during cell division. It is essential for growth, repair, and reproduction in living organisms.
- DNA replication occurs during the S phase of the cell cycle, before mitosis or meiosis.
- It transforms each chromosome into a pair of sister chromatids, held together by cohesin proteins until anaphase.
- These chromatids separate during cell division, ensuring genetic continuity.
Anaphase is the third phase of the cell cycle (more in D2.1.13 and D2.1.14 for HL students)
NoteWithout DNA replication, daughter cells would lack the full genetic blueprint, leading to malfunction or death.
DNA Replication is The Foundation of Cell Division
- Before replication, each chromosome is a single DNA molecule.
- After replication, it consists of two identical DNA molecules (sister chromatids) connected by a centromere.
- During anaphase of mitosis or meiosis II, these chromatids separate.
- This ensures that each daughter cell receives an exact copy of the DNA.
Remember: Sister chromatids are identical copies of a chromosome, while homologous chromosomes are similar but not identical.
