Mitosis

This lesson covers:

  1. Why multicellular organism require a continuous supply of new cells 
  2. What the 'cell cycle' is 
  3. What 'chromosomes' are 
  4. How mitosis works 

Names of the four stages of mitosis 


Mitosis is often described as a 4 stage process.

Diagram showing the four stages of mitosis: prophase, metaphase, anaphase, and telophase.

Remember that cells have already replicated their DNA before mitosis and each chromosome is X-shaped as it is now made up of two identical sister chromatids.

Prophase


Diagram showing the stages of mitosis with a labelled nuclear envelope and chromosomes.

The chromosomes condense (become shorter and thicker) and are now visible under a microscope.


The nuclear envelope starts to break down, leaving the chromosomes free in the cytoplasm.

Metaphase


Illustration showing the stages of mitosis with chromosomes aligned in the center of the cell.

The chromosomes line up at the equator (middle) of the cell.

Anaphase


Diagram showing spindle fibres during mitosis.

Spindle fibres contract and shorten to pull the chromatids to opposite poles of the cell. 

Telophase


Diagram showing the stages of mitosis with chromosomes, nuclear envelopes, and nuclei.

The chromatids reach the opposite poles of the cell where they uncoil to become long and thin chromosomes again. 


A nuclear envelope forms around each set of chromosomes to form two nuclei.

Cytokinesis 

Illustration showing the process of cytokinesis where the cytoplasm divides to produce two genetically identical daughter cells.

After the steps of mitosis, the cytoplasm divides in a process known as cytokinesis. This produces two daughter cells that are genetically identical to one another. 

Steps of mitosis & cytokinesis 


centre / divides / daughter / chromosomes / fibres


  1. DNA condenses to form .
  2. Chromosomes line up along the of the cells.
  3. Cell pull the two arms of each chromosome to opposite sides (poles) of the cell.
  4. Cytokinesis - the entire cell to form two identical cells.
chromosomes
centre
fibres
divides
daughter

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Multicellular organisms, like ourselves, require a continuous supply of new cells. 


What are the three reasons why new cells are required?

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What is the cell cycle?

The passage of cells around the body

The series of steps that take place as a cell grows and then divides 

The process by which molecule move around the cell

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Steps of the cell cycle 


one / two / larger / chromosomes / cell / ribosomes / DNA


  1. Cellular growth - the cell gets and produces more sub-cellular structures, such as mitochondria and . 
  2. DNA replication - duplicate, so that each consists of arms (copies).
  3. More cell growth.
  4. Mitosis - the divides into two.
  5. Cytokinesis - the divides into two.
larger
ribosomes
chromosomes
two
DNA
cell

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How many pairs of chromosomes do most human cells have?

23

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Are the cells created by mitosis genetically identical to each other, or genetically different? 

Genetically identical 

Genetically different 

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1

When a cell divides by mitosis, how many cells are produced? 

2

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1

Illustration showing daughter cells produced by mitosis.

What do we commonly call the cells produced by mitosis? 

Daughter cells 

Son cells

Offspring cells 

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1

Which stage of mitosis involves centromeres dividing to pull chromatids apart?

Anaphase

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Name the four stages of mitosis in the correct order. 

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