Cell Division
Chapter 2 Section 3
Cell Division
• The Regular sequence of growth and
division that cells undergo is known as
Cell Cycle
the_______________.
• The three main stages of the cell cycle are:
• Interphase
• Mitosis
• Cytokinesis
The Cell Cycle
Interphase
• What three things occur during Interphase?
• The cell grows
• The cell makes a copy of its DNA
• The cells prepares to divide into two cells.
Replication of DNA
• What is replication?
• The process by which
the cell makes an exact
copy of the DNA inside
of the nucleus.
Chromatin
Cell Division
• The second stage of the cell cycle during
which the cell's nucleus divides int two
Mitosis
new nuclei is called ______________.
Mitosis
•
Mitosis is divided into the following four
phases:




Prophase
Metaphase
Anaphase
Telophase
Mitosis - Prophase

Chromatin
______________
condenses and coils –
looks like rods.
Mitosis - Prophase


Each doubled rod of condensed chromatin
Chromosome
is called a _______________
and held
Centromere
together by a _______________.
Each single strand of the chromosome is
Chromatid
called a ____________.
Chromatid
Centromere
Chromatid
Mitosis - Prophase
nuclear envelope
• The __________________
beaks down
• Spindle fibers from a bridge (attached to the
centrioles).
Spindle fibers
Centrioles
Nuclear envelope
Mitosis - Metaphase
Spindle fibers
Chromosomes line up
• ______________
across the center of the
cell.
• Each chromosome
attaches to a spindle
fiber at its ___________
centromere
Chromosome
centriole
Mitosis - Anaphase
Spindle fibers
Centromeres split.
• _____________
Chromatids separate.
• Two __________
Chromatids move to
• _____________
the opposite ends of the
cell.
• Cell stretches out.
Separating chromatids
centriole
Mitosis - Telophase
Cell membrane pinches inward
Chromosomes unwind
• ____________
and lose their rod-like
appearance
nuclear envelopes
• New ______________
forms around each
region of chromosomes
• Cell membrane starts
to pinch inward.
New nuclear membrane forms
Chromosomes unwind
Cell Division – Final Stage
• The final stage of the cell cycle that follows
cytokinesis
mitosis is called _____________.
organelles
• _____________
are distributed between
the two new cells, called daughter cells
• At the end of cytokinesis, new cells enter
Interphase
_____________
and the cycle begins
again.
Cytokinesis in animal vs. plant cells
• In animal cells:
cell membrane squeezes together
• The _______________
around the middle of the cell and the
cytoplasm pinches into two new cells.
___________
• In Plant cells
cell plate
• A ___________
forms across the middle of
the cell and develops into new cell
membrane.
cell walls
• Then new ____________
form around the cell
membrane
Cytokinesis
Animal Cell
Plant Cell
Mitosis Animation
http://www.cellsalive.com/mitosis.htm
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter2/animatio
n__mitosis_and_cytokinesis.html
Length of the cell cycle
• Varies for different organisms.
2
22 hours.
• Can range from ____hours
to ____
brain
• Nerve, heart, and _______
cells never
divide. They remain in interphase for as
long as they live.
• Cancer cells divide rapidly.
DNA Structure
• DNA replication ensures that:
• The replication process ensures that each
new daughter cell will have a complete set of
DNA which it needs to carry out all the cell’s
activities.
The Discovery of the Structure of DNA
James Watson and Fransis Crick
Rosalind Franklin
DNA Structure
•
DNA looks like a twisted ladder and is
double helix
often called a ________________.
DNA Structure
a. The sides of the ladder are made up of molecules
sugar
deoxyribose
of ______________
called ______________
that
are alternating with molecules of phosphate.
DNA Structure
• Ladder rungs are made up of a pair of
molecules called nitrogen bases
(containing nitrogen and other elements).
The four nitrogen bases are:
Adenine
o ____________________(A)
Thymine
o ____________________(T)
Guanine
o ____________________(G)
Cytosine
o ____________________(C)
DNA Structure
•
How do the nitrogen bases pair up to make the
rungs of the DNA ladder?
Adenine
Thymine
o ______________
pairs only with _______________
Cytosine
Guanine
o ______________ pairs only with _______________
Nitrogen Base Pairing
DNA Replication
• DNA molecule unwinds and separates
between the nitrogen bases on each rung.
Nitrogen bases
• ____________________
that are floating
in the nucleus pair up with each half (A
with T and G with C)
• Two new DNA molecules are formed
• The order of nitrogen bases in each new
DNA molecule will exactly match the order
in the original DNA molecule.
DNA Replication
http://www.youtube.com/watch?v=hfZ8o9D1tus
Cancer
• Cancer is a disease in which:
• Cells grow and divide uncontrollably,
damaging the parts of the body around them.
• Cancer can occur when something
damages a portion of DNA in a
chromosome. This damage causes a
mutation
change in DNA called _____________.
Cancer
• Abnormal cells that develop uncontrollably
may form a mass of abnormal cells which
tumor
is called a _________________.
• Treatment for cancer include
radiation
surgery
_____________,
________________
and
Drugs (chemotherapy)
or ____________________