Cell cycle notes

G1 Phase (First Gap)

The cell grows physically larger, copies organelles, and builds proteins needed for everyday functions.

S Phase (Synthesis)

The cell duplicates its entire nuclear DNA and copies its centrosomes so each future cell gets a complete genome.

G2 Phase (Second Gap)

The cell finishes growing, stores energy, and makes microtubules to assemble the mitotic spindle.

Prophase

Loose chromatin packs tightly into visible chromosomes, the nuclear membrane dissolves, and spindle fibers extend from centrosomes moving to opposite ends of the cell.

Metaphase

Spindle fibers attach to chromosome centromeres and line the chromosomes up down the middle of the cell at the metaphase plate.

Anaphase

Sister chromatids separate and get pulled toward opposite poles of the cell as spindle fibers shorten.

Telophase

New nuclear envelopes form around each set of chromosomes at both poles, and the DNA uncoils back into chromatin.