Transcript Mitosis - Oakland H.S

Cell
Division &
Mitosis
Yay  Getting closer and
closer to the FUN stuff!!!
Cell Division
• What is cell division?
– Process where a cell splits into 2
individual daughter cells
• Why do we need cell division?
 New cells are produced for growth and to
replace damaged or old cells
• There are 2 major types
– Mitosis- division of the NUCLEUS
– Cytokinesis- division of the CYTOPLASM
DNA Replication
Replication = COPY
Original DNA
DNA must be
strand
copied or
replicated before
Two new,
cell division
identical DNA
strands
Each new cell will
then have an
identical copy of
the DNA
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Identical Daughter Cells
Two
identical
daughter
cells
Parent Cell
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Chromosomes
• These are super important
little friends
• Here are some defining
characteristics
– Made of tightly coiled DNA
– Found in the NUCLEUS
– The number depends on the
organism they live in… usually
10-50
– Humans have 46 chromosomes
in pairs (23 pairs)
Chromosomes in Dividing Cells
chromosomes are
made of 2
chromatids that
are held
together by the
centromere
Called Sister Chromatids
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Types of Cell Reproduction
Asexual reproduction -1 cell dividing
to make 2 new, identical daughter
cells
ex. Mitosis & Binary Fission
Sexual reproduction- two cells (egg &
sperm) making new cell (zygote) that
is NOT identical to the original
ex. Meiosis
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Cell Division in Prokaryotes
Prokaryotes
(bacteria)
divide into 2
identical cells
through binary
fission
Parent
cell
Chromosome
replicates
Cell splits
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2 identical daughter cells
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The cell cycle
• Cell Cycle- events cells go through as
they grow and divide
• The cell cycle consists of five phases:
– G1 (Primary Growth Phase)
• Cell increases in size
– S Phase (Synthesis)
• Chromosomes are replicated
– G2 (Second Growth Phase)
• Organelles are produced
– M Phase
• MITOSIS
– Cytokinesis
These three
phases are
known as
Interphase
Sketch me!!!
Interphase
• Not technically a part of mitosis
• Includes G1, S, and G2
• Organelles double in number to prepare
for division
Mitosis- Division of the nucleus
• These are the phases 
–
–
–
–
Prophase
Metaphase
Anaphase
Telophase
Four Mitotic Stages
Prophase
Metaphase
Anaphase
Telophase
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Prophase
• Spindle fibers form
• Centrioles move to
opposite poles
• Chromosomes
become visible
Metaphase
• Chromosomes line
up at the EQUATOR
Anaphase
• Centromeres divide
• Chromatids separate
and move to the
opposite poles
Telophase
• Nuclear membrane
forms around each
of the chromosomes
• Chromosomes
unwind
• Cytokinesis begins
Cytokinesis
• Cytoplasm
divides and
one cell
becomes two
individual
cells.
The difference
ANIMALS
Extra credit!
Cleavage Furrow is formed
PLANTS
Extra Credit
Cell Plate is formed
Cytokinesis
Cleavage furrow
in animal cell
Cell plate in
plant cell
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Mitosis in Onion Root Tips
Do you see any stages of mitosis?
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Karyotype
A picture of the
chromosomes from
a human cell
arranged in pairs by
size
Remember this! We’ll
make one of these
after Christmas!
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