Mitosis

Mitosis.

Mitosis is a type of cell division which produces 2 daughter cells that are genetically identical.

Mitosis produces daughter cells with the diploid number of chromosomes.

Mitosis is used for the growth and repair of tissues.

Never say that mitosis is used for the growth and repair of cells, this is often REJECTED!

Mitosis is part of the cell cycle. The cell cycle is made up of two main stages Interphase and Mitosis. However, Interphase can be split into several stages G1, S and G2. Interphase is not part of mitosis.

Cell cycle diagram

Cell cycle diagram supplied by Alila Medical Media. To see more cell diagrams click on the link.

 

 

 

 

As you can see from the cell cycle diagram above interphase (G1,S and G2) occupy the largest amount of time. Mitosis occupies only a small amount of the cell cycle.

G1 – Protein synthesis occurs

S – DNA Replication occurs

G2 – Organelles divide

Once interphase is complete the stages of mitosis can occur.

mitosis

Stages of Mitosis as an overview supplied by Alila Medical Media. To see more cell diagrams click on the link.

Going from the top cell to the middle cell the DNA replicates, so this represents Interphase. The mitosis is from the middle cell to the two cells at the bottom of the diagram. However, you will need to know it in more detail.

 

 

There are four main stages in mitosis:

Prophase

Metaphase

Anaphase

Telophase

Just after telophase a process called cytokinesis will occur that involves splitting the cytoplasm.

At the beginning of mitosis the cell will look like this:

cell at the start of mitosis

© Dreamy Girl – Fotolia.com

 

 

 

 

The cell will go through prophase and several things will happen:

Nuclear envelope will breakdown

Chromosomes will shorten and thicken

Centrioles will move to opposite ends of the cell

Spindle fibres will start to form

The cell will now look like this:

Prophase of mitosis

© Dreamy Girl – Fotolia.com

 

 

 

 

 

The cell will now undergo its next stage which is metaphase. During this stage the following will happen:

Chromosomes will align themselves along the equator of the cell. They will be attached to spindle fibres at their centromere. A cell in metaphase will look like the one below:

Metaphase mitosis

© Dreamy Girl – Fotolia.com

 

 

 

 

The next stage of mitosis is Anaphase. During anaphase the following will happen:

Chromosomes split at the centromere and the individual chromatids are pulled to opposite poles of the cells by the spindle fibres. A cell in anaphase looks like the one below:

Anaphase of mitosis

© Dreamy Girl – Fotolia.com

 

 

 

 

After Anaphase, telophase occurs and the following happens:

Nuclear envelope forms around each set of chromosomes

Spindle fibres break down

The cell will then split by cytokinesis and you will see the following transformation:

cell 5

© Dreamy Girl – Fotolia.com

 

 

 

 

 

 

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