DNA replication:

It's a period of intense biochemical activity where the cell synthesizes proteins, copies organelles, and accumulates the necessary molecular building blocks

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Part 1 Interphase Continued: G1 Phase (Gap 1): Part 2:

Decision Point:

At the end of G1, the cell reaches a crucial decision point called the G1 checkpoint (also known as the restriction point). This checkpoint assesses whether the cell has reached a sufficient size, has enough resources, and if there is any DNA damage. 

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Part 1 Interphase Continued: G1 Phase (Gap 1): Part 3:

Commitment to Division or Entry into G0:

If the cell passes the G1 checkpoint, it commits to proceeding with DNA replication in the S phase. If conditions are not favorable, or if the cell is specialized and does not need to divide, it may enter a non-dividing state called G0

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Story

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Part 1 Interphase Continued: S Phase (Synthesis): Part 1:

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 DNA Replication:

The primary event is the duplication of the cell's DNA. Each chromosome is replicated, resulting in two identical sister chromatids joined at the centromere

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Sister Chromatids:

The replicated DNA molecules are now organized into sister chromatids, which are held together by cohesin proteins

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Centrosome Duplication:

The centrosome, which plays a vital role in organizing microtubules during cell division, is also duplicated during the S phase

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Histone Synthesis:

Histones, the proteins that DNA wraps around, are synthesized during this phase to accommodate the replicated DNA

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Chromatin Configuration:

Throughout interphase, including the S phase, DNA remains in a semi-condensed chromatin configuration, not the tightly condensed form seen in mitosis

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Part 1 Interphase Continued: S Phase (Synthesis): Part 6:

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Checkpoint Control:

Cells have mechanisms to check if DNA replication is complete and accurate before proceeding to the next phase (G2 phase and then mitosis)