Transcript Mitosis- Dance of the Chromosomes

Mitosis- Dance of the
Chromosomes
Ehenside Science
What is Mitosis?

Mitosis is the process by which eukaryotic
cells divide.
 Prokaryotes divide through a simpler
process called binary fission.
What is the purpose of Mitosis?

When single celled organisms go through
mitosis, they are reproducing: there are now
two new organsims (reproduction).
 Multicellular organisms go through mitosis
to produce new cells to grow or to replace
dying or damaged cells (growth and repair).
Key terms

Chromosome- structure made of highly
coiled or condensed DNA.
 Chromatin – the uncoiled form of DNA.
 Sister chromatids – two identical sections
(copies) of DNA joined together at the
centromere.
 Pictures on next slide
Often confused terms

3. Single strand of
chromatin.
 4. Two sister
chromatids joined at
centromere.
 5. Replicated or double
stranded chromosome
after condensation.
Each half is still
considered a sister
chromatid.
Gap1
Synthesis
Prophase
What is the cell cycle?

All cells pass through a series of events
called the cell cycle.
 Some cells cycle continually, other cell
types only a limited number of times before
they die.
Cell Cycle
Only one
hour out of
22 is spent
in active
division
(Mitosis)
Relationship of Stages

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Interphase consists of:
Gap 1 (G1)
Synthesis (S)
Gap 2 (G2)
Total time: 21 hours

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Mitosis consists of:
Prophase
Metaphase
Anaphase
Telophase
Total time: 1 hour
Interphase

Typical Cell spends
95% of its time in
interphase
 Centrioles replicate
during Gap 1
 DNA copies itself
during Synthesis
 Growth occurs during
all three phases.
What’s the DNA doing?

Chromatin in Gap 1
 Replicates in
Synthesis
 Condenses into
chromosome during
early mitosis
(prophase).
Relationship of Stages





Interphase consists of:
Gap 1 (G1)
Synthesis (S)
Gap 2 (G2)
Total time: 21 hours

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Mitosis consists of:
Prophase
Metaphase
Anaphase
Telophase
Total time: 1 hour
Prophase

Chromatin starts to coil into
chromosomes
 Nuclear membrane starts to
dissolve
 Centrioles moving to opposite ends
of cell
 By end, chromosomes fully
formed, nuclear membrane gone,
and centrioles at opposite ends of
cell.
Metaphase

All chromosomes line
up on equator of cell
 Spindle fibers attach
to each chromosome
Anaphase

Spindle fibers contract
and pull sister
chromatids apart
 Full set of DNA
eventually pulled to
opposite ends of cell.
Telophase

Chromosomes begin to uncoil
 Nuclear membrane begins to reform
 In plants, cell plate forms to divide
cytoplasm
 In animals, cleavage furrow forms to
divide cytoplasm
Mitosis Videos 1
Mitosis in the lung cell of a Newt.
Mitosis Videos 2
Microtubules and endoplasmic reticulum in Newt lung cell.
Any Questions?