Post on 22-Feb-2016
description
transcript
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