Mitosis

You started off as a cell smaller than the period at the end of a sentence………

Where it all began…….

And now look at you!

How do you get from being smaller than a “period” to a growing human being?

Going from egg to baby…. the original fertilized egg has to

divide… and divide…

and divide…and divide…

Getting from here to there

Growth From fertilized egg to multicellular organism

Repair Replace cells from normal wear and tear and

injury

Reproduction Asexual Reproduction (1 celled organisms)

Why do cells divide?

The cell cycle is the process by which the cell grows and divides to make copies of itself

The life of a cell is divided into 2 stages: Mitosis (Division of nuclear material) Cytokinesis (Division of cytoplasm and

organelles)

What is the Cell cycle?

Cells in Interphase for about 90% of their life Your cell muscles are constantly breaking apart and

being replaced, the cells in your small intestine are constantly absorbing nutrients and cells are always dividing.

A cell doing its “everyday job” as well by making proteins, enzymes and etc…

Interphase

DNA REPLICATION

We know that DNA can replicate by “unzipping”, and then rejoining itself

When it creates a copy of itself, the copy is called the sister Chromatids

Mitosis

Chromosome

Spindle Fibre

Cytokinesis starts

Nucleus

There are 5 parts (four steps) in Mitosis. 1 Interphase, 2 Prophase, 3 Metaphase, 4

Anaphase, 5 Telophase (and here is where the sister cell is found)

1 2 3 4 5

Chromosomes coil up into an X-Shaped chromosome

Spindle Fibers form and stretch across the centrioles at opposite ends of the cell

Chromosomes attach to spindle fibers at their centromeres

Nucleolus disappears and the nuclear membrane breaks down

Prophase

Centrioles (a part of the cell): Produce spindle fibers, and help organize the spindle fibers during cell division

Spindle Fibers : Attach to the centromeres and direct the process of cell division

Centromere : Hold the sister chromatids together

Prophase

Spindle fibers

Sister Chromatids

Centrioles

Plasma Membrane

Centromere

Nuclear membrane

Spindle fibers pull chromosomes towards the middle of the cell

The Chromosomes line up across the middle and prepare to split

Metaphase

Sister Chromosomes separate at the centromeres

Spindle fibers pull the sister chromatids to the opposite side of the cell

Anaphase

1 chromosome2 sister chromatidsDouble Stranded

2 chromosomesSingle Stranded

Spindle fibers disappear

Nuclear Membrane forms around each set of chromosomes

A nucleolus appears in each nucleus

No there are two nuclei in one (1) cell

Telophase

This process is what starts the Mitosis process.

The cell membrane pinches together to divide the cells cytoplasm and organelles.

The two nuclei are separated into 2 new daughter cells

New daughter cells are identical to parent cell

Cytokinesis

Chromosomes line up at the Equator

Sister Chromosomes

separate and are pulled to the

opposite sides of the cell

Cytoplasm divides and two new daughter cells

are formed that are genetically identical to

the parent cell

Mitosis