Functions of Cell Division
Repair
when a cell is damaged, it is replaced with a new cell
Growth
needed so that living organisms can develop into mature
organisms
needed to replace old and dying cells
The Cell Cycle
Every cell goes through a cycle where it grows then divides.
There are two important phases in the Cell Cycle: interphase
and mitosis.
Interphase:
 The phase when the cell grows and then makes a
copy of its genetic material when it is ready to
divide
Mitosis:
 The phase when cell division takes place
 There are 4 phases in mitosis:
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Prophase
Metaphase
Anaphase
Telophase
Mitosis is the process of cell division. It involves the
duplication of the material inside the nucleus and the sharing
of certain organelles.
Phases of Mitosis
There are four phases in mitosis, each phase is named with a
Greek prefix. There is also a phase that occurs just before
mitosis which is called interphase. Understanding the meaning
of these prefixes will help you to understand what is
happening during each stage.
Mitosis is a continuous process. There is no starting or
stopping during the process. For example, throwing a ball has
a number of phases (set up, back swing, throwing, release and
follow through), but it looks like one movement.
Prefixes and Phases
Interphase
Inter means “between”
The cell spends most of its time in this phase
This is the phase in which the cell grows
When it is ready to divide, the cell makes a copy of its
genetic material (this takes place in the nucleus)
 The cell membrane and nuclear membrane are visible
 Chromosomes will duplicate during this phase and
remain invisible
 Double-stranded chromosomes contain two complete
sets of DNA
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1. Prophase
 Pro means “before”
 Chromosomes become visible again (they thicken
and lengthen)
 Nuclear membrane begins to disappear
 Centromeres form and become visible
 Centrioles form at either ends of the cell
 Spindle fibres form from the centrioles and attach
to the centromere
2. Metaphase
 Meta means “middle”
 Double stranded chromosomes line up in the middle
of the cell
 Double-stranded chromosomes line up along the
equator (middle) of the cell
3. Anaphase
 Ana means “up”
 The spindle fibres shorten and pull the centromeres
apart
 The chromosomes split and single strands of
genetic information are pulled to opposite ends of
the cell by the spindle fibres (one strand from each
double-stranded chromosome moves to opposite
sides of the cell)
4. Telophase
Telo means “end”
The spindle fibres disappear
The two halves of the cell reorganize
New nuclear membrane forms around two new
identical nuclei
 Chromosomes uncoil and become invisible again
 Cytokinesis occurs – the cell divides into TWO
identical daughter cells
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