How many stages of
cell division did you see?
3 Reasons Why Cells Reproduce
Growth
Repair
Replacement
Why Would a Cell Divide?
 As cells absorb nutrients and get larger, the volume of the cell
increases faster than the surface area
Surface area for
exchange not great
enough to support cell’s
needs
 This means that a cell can no longer absorb nutrients and get
rid of wastes fast enough to support its demands (volume)
 So what’s a cell to do? Solution: divide in 2!
Cell division is a type of
asexual reproduction.
The Cell Cycle has 3 stages:
1) INTERPHASE
2) MITOSIS
-Prophase
-Metaphase
-Anaphase
-Telophase
3) CYTOKINESIS
INTERPHASE
•
Longest phase of the cell cycle (90%
of time in Interphase)
•
Cell grows & makes proteins
•
Replicates its DNA and
chromosomes
•
Makes organelles for division, like
centrioles
INTERPHASE (for real)
Animal Cell
Plant Cell
Chromosome
• Inside nucleus
• Genetic information (DNA)
• After S phase = 2 sister chromatids
Review Question (whiteboard)
Draw a chromosome on your
whiteboard and circle 1 chromatid
There are different
# chromosomes
for different species
Which species do you think has the most chromosomes?
Ewoks
?
Humans
46
Shrimp
86-90
Adders tongue
1260
Mitosis
= Division of nucleus
• Prophase
• Metaphase
• Anaphase
• Telophase
st
1
Stage in Mitosis: PROPHASE
• Chromatin condenses into
chromosomes.
• Nuclear envelope breaks down
• Centrioles separate to opposite
sides of the cell
• Spindle begins to form between
centrioles (made of microtubules)
Prophase (for real)
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
nd
2
Stage in Mitosis: METAPHASE
• Chromosomes line up at the center
of the cell (meta means “middle”)
• Spindle fibers attach to each sister
chromatid at its centromere
Metaphase (for real)
Animal Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Plant Cell
rd
3
Stage in Mitosis: ANAPHASE
• Sister chromatids separate and
the centromeres divide
• Pulled apart by the shortening
of the spindle fibers
• Sister chromatids move to
opposite poles of the cell
Anaphase (for real)
Animal Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Plant Cell
th
4
Stage in Mitosis: TELOPHASE
• Chromosomes begin to
uncoil and become
chromatin
• Nuclear envelope begins to
form around genetic
material (chromatin).
• 2 distinct nuclei are forming!
Telophase (for real)
Animal Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Plant Cell
AFTER MITOSIS: CYTOKINESIS
• Cytoplasm pinches in
half
• Two daughter cells are
formed with identical
genetic information.
• Cell cycle starts all over
again!
What happens if cells
start to multiply uncontrollably?
CANCER! – uncontrolled cell growth leading to
masses of cells called tumors
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Let’s watch it in action!
Can you tell when each stage begins?
Narrate the Animation
COOKIE MITOSIS!!!
Cell Cycle
Label each
stage &
place in
the
correct
order!
24