Cell Division: Mitosis, Bacterial Fission & Cell Cycle Stages

Cell Division

Requires precise DNA copying/replication, equal DNA distribution, and separation of new 'daughter' cells.

Bacterial Division

Uses 'Binary Fission' and is considered simpler, with 1/1000th the DNA.

Steps of Bacterial Division

1. Chromosomal replication, 2. Growth with separation (size doubling; membrane pinching), 3. Cell wall reconstruction.

Eukaryote Division - Mitosis

Involves more DNA and more complicated steps, with many more chromosomes.

Steps of Eukaryote Division - Mitosis

1. Chromosome replication, 2. Separation of copies (chromatids) into the 'new' cells, 3. Cytokinesis (cell separation).

The Cell Cycle

Includes actual separation time plus time for doubling of organelles and cytoplasm, with dividing and non-dividing periods.

Doubling Times

Can vary and are cell-specific.

Interphase

The non-dividing phase that comprises the majority of the cell cycle, where DNA is packed loosely and not visible.

Prophase

Nuclear envelope begins to breakdown, copied DNA condenses (forming sister chromatids), and centrosomes separate to opposite sides producing spindle fibers.

Prometaphase

Further breakdown of the nuclear envelope and spindle fibers extend further from centrosomes & connect to chromosomes.

Metaphase

Chromosomes align on a central plane - 'plate', with centrosomes at opposite poles and spindles fully attached to chromosomes.

Anaphase

Chromosomes separate by microtubules shortening, with 'motors' used to separate chromosomes and ATP utilized.

Telophase

Cell elongates further, daughter cell nuclei form their own nuclear membrane, DNA decondenses, and cells develop cleavage furrow.

Cytokinesis

Forms new cells using the cytoskeleton in a 'purse-string' mechanism.

Cell Division Check Points

Points where the cell performs a 'self-diagnosis' to ensure readiness to proceed to the next stage.