Cell Reproduction

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Chapter 3 Cell Reproduction Section 1 Cell
Division
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• Cell Reproduction
• Why do cells need to reproduce?
• 1. new cells are needed to replace
• old or damaged cells when
• fresh cells are needed
• 2. new cells allow organisms to
• grow

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B. Reproduction by Division 1. divide
(split) to reproduce ?parent cell the original
cell ?daughter cells 2 new cells that
form when the parent cell divides 2. specific
stages in reproduction cycle
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STAGE 1 INTERPHASE 1. BEFORE mitosis
(getting prepared for mitosis) 2. MOST of
a cells life
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Interphase
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3. cell matures to full size 4. cell
GROWS and produces
all it needs to carry out all
of its life functions even after
division takes place 5. more organelles are
made EX the ER doubles, more ribosomes are
made, copies are made of mitochondria and
chloroplasts, etc.
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6. the parent cell copies or
duplicates its DNA -Now, with 2 sets of
DNA, each daughter cell that will be
produced can have a full copy of the DNA
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?DNA (deoxyribonucleic acid) -hereditary
material found in a cells
nucleus -contains ALL instructions to
carry out a cells life functions -DNA makes up
threadlike structures called
chromosomes (sowhen DNA duplicates,
the of chromosomes
will)
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chromosome
-found in the nucleus -made of DNA (master
instructions) -each rod is a chromosome each
chromosome is connected to a copy of itself at
the centromere
centromere
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DNA
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DNA
chromatid
chromatin
chromosome
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http//mywebpages.comcast.net/llpellegrini/meiosis
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STAGE 2 MITOSIS 1. cells divide to
reproduce 2. the division forms 2
daughter cells exactly the SAME as the
parent cell 3. 4 Phases
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• ?PROPHASE (Phase 1)
• material in nucleus breaks apart
• 2. chromosomes twist and thicken and move to
  center of the cell
• 3. chromosomes are now doubled (from being copied
  in interphase)
• 4. centrioles go to ends of the cell
• 5. thin tubes, called spindle fibers, form
  between the centrioles

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Prophase
spindle fibers
centrioles
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?METAPHASE (Phase 2) 1. spindle fibers (threads)
push and pull the chromosomes until they are in a
line across the MIDDLE of the cell 2. fibers
are attached to each centromere
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Metaphase
http//mywebpages.comcast.net/llpellegrini/meiosis
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• ?ANAPHASE (Phase 3)
• spindle fibers shorten and pull each chromosome
  pair APART at the centromere (center)

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Anaphase
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• ?TELOPHASE (Phase 4)
• last step where cells finish dividing
• membrane pinches together cytoplasm splits in
  two
• (in plant cells, the cytoplasm is divided by a
  cell plate)

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3. new cells separate into 2 daughter cells
4. each daughter cell now has the same number of
chromosomes that the parent cell began with 5.
chromosomes untwist and become long and thin
again inside nucleus
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Telophase
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• daughter cells now are ready to begin their own
  interphase
• THE CYCLE CONTINUES!

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Cell Division Stage 1 Interphase Stage 2
Mitosis 1) Prophase 2) Metaphase 3)
Anaphase 4) Telophase (2 daughter cells)
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Mitosis
http//www.accessexcellence.org/AB/GG/mitosis.html
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Prophase
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Metaphase
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Anaphase
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Telophase
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Interphase
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Prophase
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Metaphase
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Anaphase
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Telophase
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Animal Cell Mitosis (animated) http//www.cellsali
ve.com/mitosis.htm