Mitosis and Cytokinesis

Chapter 6.3

The Cell Cycle

The Cell Cycle is a repeating sequence of cellular growth & division during the life of an organism.

Pre Mitosis- InterphasePhase of cell division when the cell

copies its DNA grows larger & prepares to divide.

A cell spends 90% of its lifetime in Interphase

There are 3 sections of Interphase: G1, S, and G2

Interphase- G1 Phase

“G1” Phase= First Growth phase90% of the cells life is spent in the G1 phase\Carries out routine functions, growsSome muscle and nerve cells never leave this

stage… what does this mean?

Interphase- “S” phase“S” phase = Synthesis PhaseDNA is copied

Interphase- G2 Phase

“G2” Phase= 2nd Growth PhaseMicrotubules form to prepare for divisionMicrotubules- Hollow protein fibers that help

pull chromosomes apart

Mitosis!Mitosis- Process of cell division where the

nucleus dividesOccurs in 4 Steps

ProphaseMetaphaseAnaphaseTelophase

Mitosis Stage 1- ProphaseNucleus Breaks DownSpindle Forms to pull microtubulesChromosomes are visible

Mitosis Stage 2- MetaphaseChromosomes line up at the equator

Mitosis Stage 3- AnaphaseChromosomes splitChromosomes are pulled to opposite sides of

the cell

Mitosis Stage 4- TelophaseThe Nucleus reappearsThe cell begins to split

Post Mitosis- CytokinesisThe cell splits into two cells by:

Cleavage Furrow- occurs in animal cells/ cells without cell walls

Cell Plate Formation- occurs in plant cells/ cells with cell walls

IMPORTANT !!!!!!!!!Interphase and Cytokinesis are NOT

considered Mitosis!MITOSIS is ONLY…

PROPHASEMETAPHASEANAPHASETELOPHASE