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Chapter 10
Cell Growth & Division
10.1 Cell Growth
• Cells can’t grow forever
– Larger cells 
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Higher demand on DNA to make more proteins
Need more nutrients
Surface area!
Have more wastes
Ex: large city
10.1 Cell Growth
• Cells can’t grow forever
– Compare surface area to volume
10.1 Cell Growth
• Cell division
– Cell divides to form 2 identical “daughter”
cells
• Copies all genetic material (DNA)
• Copies organelles
10.2 Cell Division
• Chromosomes
– Review:
• DNA wrap around
histones which form
bundles called
nucleosomes
• The nucleosomes coil
around each other to
ultimately form a
chromosome
10.2 Cell Division
• Chromosomes
– 2 sister chromatids
• Remember replication?
– Centromere
• Where chromatids are
attached
10.2 Cell Division
• Chromosomes
– Each org. has specific
# chromosomes
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Humans 46 (23 pairs)
Dogs 78 (39 pairs)
Cats 38 (19 pairs)
Carrots 18 (9 pairs)
10.2 Cell Division
• Cell Cycle
– Interphase  “in-between phase”
• G1 phase  cell growth
• S phase  DNA replicates
• G2 phase  prepare for mitosis
10.2 Cell Division
• Cell Cycle
– Mitosis (M phase)
• 4 phases
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Prophase
Metaphase
Anaphase
Telophase
10.2 Cell Division
• Cell Cycle
– Mitosis (M phase)
• Prophase
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Longest phase of mitosis
Chromosomes become visible (why?)
Centriols move to opposite sides
Spindle fibers form & attach to chromosome @ the
centromere
– Nucleolus disappears
– Nuclear envelope breaks down
10.2 Cell Division
• Cell Cycle
– Mitosis (M phase)
• Metaphase
– Chromosomes line up
– Microtubules connect to the centromere
10.2 Cell Division
• Cell Cycle
– Mitosis (M phase)
• Anaphase
– Centromeres split & sister chromatids separate
– Ends when chromosomes stop moving
10.2 Cell Division
• Cell Cycle
– Mitosis (M phase)
• Telophase
– Chromosomes unwind
– Nuclear envelope reforms
mitosis is done!
10.2 Cell Division
• Mitosis
– Division of nucleus  1 nucleus becomes 2
• Happens in cytoplasm of one cell
– How unicellular organisms reproduce
• Asexual reproduction
– How multicellular organisms grow & replace
old, damaged, or dead cells
• Cytokinesis
– Division of cytoplasm
10.2 Cell Division
• Cytokinesis
– Division of cytoplasm
• Animal cells – membrane pinches in & seals off
• Plant cells – cell plate
• http://www.pbs.org/wgbh/nova/miracle
/divide.html
• Mitosis vs. meiosis