Cell DivisionUnit 3 Part 2 – The Cell

Cell CyclesPROKARYOTIC CELLS EUKARYOTIC CELLS

No nucleus. No membrane bound

organelles. (ex. mitochondria, vacuole, chloroplast)• A.) Cell division

takes place in 2 steps: 1.) DNA is copied. 2.) Cell splits by binary fission.

Contain a nucleus and organelles.

Have a cell cycle.• Repeating

sequence of growth and division.

Eukaryotic Cell Cycle 5 Stages

• G1 First growth phase

• S Synthesis phase

• G2 Second growth phase

• Mitosis Cell division

• Cytokinesis Division of cytoplasm

Interphase This is when the

cell is preparing to divide.

The LONGEST phase of the cell .cycle

90% of the cell’s life is spent in Interphase

G1 – first growth phase:• The cell doubles in

size and the organelles double.

S – synthesis phase:• the DNA that makes

up the chromatin is copied (DNA replication) this is the longest phase of interphase.

G2 – second growth phase:• Growth and

preparation for mitosis.

Interphase (G1, S, G2)

Mitosis (PMAT) Mitosis

• The nucleus of a cell is divided into two nuclei with the same number of chromosomes.

• Consists of 4 phases Prophase Metaphase Anaphase Telophase

Terms to know for mitosis Chromosome

• Single piece of coiled DNA.

Replicated Chromosome• A single piece of DNA

that has been copied through DNA replication.

Sister Chromatids• 2 identical strands of

DNA. Non-Replicated

Chromosome• Single strand of DNA

before it is copied.

Spindle Fibers• Fibers that extend from

the centrioles and help to pull apart chromosomes.

Centrioles• Organelles that aid in

pulling apart replicated chromosomes.

Centromere• Structure that holds the

replicated chromosomes together.

Sister Chromatids

Replicated Chromosome

Centromere

Non-Replicated Chromosome

Prophase Longest phase of

MITOSIS• Chromatin coils and

forms chromosomes• Nuclear envelope

breaks down• Spindle fibers form

and stretch from one end of the cell to the other They attach to the centrioles

They help to pull the cell apart

Metaphase Chromosomes line

up in the middle of the cell.

Anaphase Centromere of each

chromosome splits. Two sister

chromatids separate and move to opposite poles.

Each chromatid becomes separate (non-replicated) chromosome in each daughter cell.

Telophase Last stage of

Mitosis. Chromosomes at

each pole uncoil and become chromatin.

Nuclear envelope reforms.

Spindle fibers break down.

Cytokinesis NOT part of mitosis. The cytoplasm

divides into two cells.

Cell membrane reforms.

In plant cells the cell wall reforms.

Click the image to play the video segment.

Video 1

Animal Cell Mitosis