Transcript Cell Division - ScienceRocks8

Key Concepts
•What events take place during the
three stages of the cell cycle?
•How does the structure of DNA help
account for the way in which DNA
copies itself?
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Cell cycle
Interphase
Replication
Mitosis
Chromosome
cytokinesis
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Cell Cycle – the regular
sequence of growth and
division that cells undergo
◦ Cells grow, divide into 2 cells
called daughter cells
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Interphase is the period
before cell division where
the cell grows, makes a
copy of its DNA, and
prepares to divide into 2
cells
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Growing – during first part
grows to full size and
produces structures it needs.
– Makes copies of both
mitochondria and chloroplasts
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Copying DNA – makes exact
copy of DNA in a process
called replication (each
daughter cell must have a
complete set of DNA
Preparing for division- cell
produces structures it will
use to divide into 2 cells
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The stage during which
the cell’s nucleus divides
into 2 new nuclei
One copy of the DNA is
distributed to each
daughter cell
Mitosis has 4 parts or
phases:
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Prophase
Metaphase
Anaphase
Telophase
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Chromatin condenses to form chromosomes
Chromosomes are double-rod structures.
They are double because the DNA in the cell
has replicated ( made a copy of itself)
Each identical rod is called a chromatid
The two chromatids are
held together by
a centromere
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Chromosomes line up across the center of
the cell.
Each chromosome attaches to a spindle fiber
at centromere
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Centromeres split. 2 chromatids separate and
are drawn by spindle fibers to opposite sides
of the cell
The cell stretches out
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Chromosomes stretch out. Lose rod-like
appearance
New nuclear envelope forms around each
region of chromosomes
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Final stage of cell cycle
The cytoplasm divides. The organelles are
distributed into each of the 2 new cells
Starts at same time as telophase
Ends and the cell goes into interphase
In animals, cell membrane pinches in
In plants, a cell plate forms across the
middle of the cell. Gradually develops into
new cell membranes. Then new cell walls
form around the membrane
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Structure was discovered through the work of
3 scientists:
Rosalind Franklin – used an x-ray method to
photograph DNA molecules in 1952
James Watson and Francis Crick – used
photographs to create a 3-D model showing
the helical (spiral) structure of DNA in 1953
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Looks like a twisted ladder or spiral staircase
Sides are made of a sugar – deoxyribose
alternating with a phosphate
Rungs are pairs of molecules called nitrogen
bases. 4 types: adenine (A), thymine (T),
guanine (G), and cytosine (C)
Adenine only pairs with thymine
Guanine only pairs with cytosine
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2 sides of DNA molecule unwind and
separate
Nitrogen bases that are floating in
nucleus pair up with bases on either
side.
Because of the way in which N bases
pair with one another, the order of
bases in the new strands of DNA are
exactly the same as the original
strand
Ends with 2 strands of DNA
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http://botit.botany.wisc.edu/images/130/meiosi
s/lilium_microsporogenesis/interphase.html
http://members.chello.nl/r.kuijt/en_mitosis.htm
http://allstrangledup.wordpress.com/
http://student.ccbcmd.edu/~gkaiser/biotutorials
/dna/mitosis/pcinterphase.html
http://imcurious.wikispaces.com/Midterm+Exam
+2010+Review+P2
http://www.cas.unt.edu/~tpp001/Mitosis_Diagra
m_Page.main.html
http://www.dna-sequencing-service.com/dnasequencing/dna-structure/
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http://www.achievement.org/autodoc/photoc
redit/achievers/wat0-032
http://sciencecomm.wikispaces.com/UNIT+2
_Did+Rosalind+Franklin+deserve+the+Noble
+Prize%3F
http://www.packer34.freeserve.co.uk/remem
beringfranciscrickacelebration.htm
http://library.thinkquest.org/C006188/basic
s/replication.htm