MITOSIS
Cell division
Review – check your understanding
• What is a cell?
• What is the difference between a prokaryotic cell and a
eukaryotic cell?
• What type of cells are you made up of?
• Do cells live forever?
Cell division - Replication
All complex organisms
originated from a single
fertilized egg – 1 cell.
Every cell in your body
started from this one cell
and increased in numbers
through cell division.
Cells then specialize and
take on different roles
within the body.
Cells must divide to:
replace old, dead cells or
damaged cells
Types of Cell Division
• Asexual Reproduction – only one parent cell needed to
create a new cell
• Sexual – two parents cells needed
Types of cell division
1. Mitosis = Eukaryotic cells
The process by which eukaryotic cells divide
to form 2 identical daughter cells. The
nucleus and all of its contents divide.
Types of cell division
2. Binary Fission = Prokaryotic cells
The process by which
prokaryotic cells divide
to form two
roughly equal cells.
The life of a Eukaryotic Cell
• Cell cycle – the life cycle of a cell:
patterns of growth, DNA duplication,
and cell division.
4 stages of Cell Cycle
1. Gap 1 (G1) – most of it’s lifespan
• Carries out normal functions
• Increases in size
• Organelles are duplicated
• Checkpoint 1 - Cannot move on to next
stage until cell has grown and duplicated
all organelles.
4 stages of Cell Cycle
2. Synthesis (S) – “to make”
• DNA synthesis – the cell makes a copy
of its DNA
• By the end of this stage, the cell’s
nucleus has two complete sets of DNA
4 stages of Cell Cycle
3. Gap 2 (G2) – more growth
• Cell carries out normal functions
• Additional growth occurs
• Critical checkpoint 2 – Before the cell
can divide it must be big enough and
have 2 undamaged copies of DNA
4 stages of Cell Cycle
4. Mitosis – The division of the cell nucleus
and contents.
• The cell completely divides in half
splitting the DNA
• Result = TWO Identical Cells (Daughter
Cells)
Types of white blood
cells
Table shows
Length of G1
Stage before
cells divide.
Type of white blood cell
Type of white blood cell
Line blood vessels
Mitosis is for:
Reasons for Mitosis:
• Growth
• Cell replacement (old or damaged cells)
Mitosis occurs in all cells in your body
except eggs and sperm.
Parent cell
DNA is copied and
doubles in number
(Called
chromosomes)
DNA
(Chromosomes)
now split
2 daughter cells are
made identical to the
original
KEY TERMS to understand
• Chromosomes - 1 long continuous thread
of DNA that consists of numerous genes
Your cells each have 46 chromosomes
– 23 pairs
(storehouses of all your DNA)
DNA strands are so long, they need to fit
nicely inside of your cell’s nuclei.
Structure of chromosomes
• DNA – stores genetic information, double
helix, long strands, each continuous strand
makes 1 chromosome
• Histone proteins – DNA wraps around
these to better fit into the nucleus, keeps
DNA organized and not “tangled”
Structure of chromosomes
• Chromatid – One half of a chromosome
Chromosomes are “X” shaped – one half of
the X is a chromatid, both halves are
together called sister chromatids.
• Centromere – holds the chromosome
together, a region that looks pinched.
The middle of the “X”
Phases of Mitosis:
1.
Interphase =
a. cells grow, copy their DNA and
copy all organelles
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in notes 
Phases of Mitosis
2.
Prophase =
a. DNA shrinks into tightly coiled
chromosomes
b. Nuclear Envelope breaks down
(membrane around nucleus)
c. Centrioles begin to move to
opposite ends of the cell
d. Spindle fibers form
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in notes 
KEY TERMS
• Centrioles - organelles that help in
cell division and make spindle fibers
• Spindle Fibers – fibers that pull apart
the chromosomes when a cell divides
Centrioles
Spindle Fibers
Phases of Mitosis
Metaphase
• Spindle fibers attach to each
chromosome
• Spindle fibers align the
chromosomes along the middle of
the cell
3.
Metaphase – Chromosomes in Middle
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in notes 
Phases of Mitosis
4.
Anaphase
• Chromosomes separate to opposite
sides of the cell.
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in notes 
Phases of Mitosis
5.
Telophase
• Each set of chromosomes are on
opposite sides of the cell
• Nuclear membrane forms around
each set of chromosomes
• Chromosomes begin to uncoil
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in notes 
CYTOKINESIS
Cytokinesis = divides the cell into two cells
and completes the process of mitosis and
the cell cycle.
RESULT of MITOSIS = 2 daughter cells
(Daughter cells are identical to the original
parent cell)
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in notes 
Remembering the phases
Cell Cycle:
G1, S, G2 = Interphase
Mitosis = Prophase –
Metaphase –
Anaphase –
Telophase –
Mitosis – Bone Cell Slides
Parent cell
Chromosomes
copied
2 daughter
cells
Copies
separating
Plants
apical
meristem
Rat – epithelial cells
Factors that affect cell division
• Growth factors – proteins that
stimulate cell growth – bind to
receptors on cells
• Apoptosis – programmed cell death,
when cells need to die (webbed
fingers in womb)
Factors that affect cell division
• Cancer – uncontrolled cell division;
Forms tumors
• Benign – clumped together, mostly
harmless, easily removed
• Malignant – some of the cells could break
away to go form tumors elsewhere,
makes it hard to remove all the cancer
Cancer
• Cancer cells are harmful because they do not
preform the specialized functions needed by the
body.
• Cancer cells require lots of food and blood
supply, they are stealing essentials materials from
the body without contributing
• Cancer cells are a result of normal cells that have
suffered damage to the genes that help regulate
the cell cycle.