Download The Cell Cycle - Cope Middle School

The Cell Cycle
Chapter 2: Section 3
What Is The Cell Cycle?
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The regular sequence of growth and
division that cell undergo
Check out Pages 54 & 55!
Know the events that occur as one parent
cell becomes two daughter cells!
Remember This?
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multicellular organism: cells are the same size
if you are a whale or a mouse
Reasons Why Cell Size Is Limited:
size is related to function; i.e. red blood cells
volume increases more rapidly than surface
area
surface area of membrane cannot support
volume of cytoplasm inside (diffusion): cell
would die
nucleus can only control so much cytoplasm
INTERPHASE
 Interphase
- period between cell
divisions
 - genetic material in form of chromatin
 - nucleus surrounded by membrane
 - nucleolus (1 or more) present and
visible
 - DNA replicates (makes a copy of
itself)
Interphase
Mitosis
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cell division; process of duplicating and
dividing chromosomes; growth and repair
parent cells: cells that divide
daughter cells: cells that result from
division; each daughter cell has exactly the
same number and type of chromosome as
parent cell
mitosis is an ongoing cell process but we
can identify 5 main stages or phases:
Prophase
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"first" phase
- chromatin shortens and thickens into
chromosomes
- chromosomes are paired into sister
chromatids
- nucleoli & nuclear membrane "disappear"
- spindle fibers form from each pole(end) of
cell
- middle of cell now called equator
Prophase
Metaphase
 "middle"
phase
 - chromosomes move to
equator and line up
 - paired chromosomes are
attached to spindle fibers
Metaphase
Anaphase
-
sister chromatids separate
toward opposite poles
 - appear to be pulled by
shortening spindle fibers
 - phase ends when chromatids
reach poles
Anaphase
Telophase
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chromosomes become chromatin
again
 - spindle fibers disappear
 - "new' nuclei appear with nucleoli
 - cytoplasm divides at equator
(cytokinesis)
 - 2 new daughter cells result
Telophase
Cytokinesis
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Cytoplasm divides
Organelles distributed into each new
daughter cell
Animal cell = “cleavage”
Plant cell = “cell plate”
Daughter cells enter Interphase
Animal vs. Plant Cell
 *animal
cells: cell membrane pinches
off
 **plant cells: formation of cell plate
which becomes new cell wall
 some cells are so specialized that they
don't divide; red blood cells; nerve
cells
 cells spend most of their time in
interphase
Chromosomes & Replication
Replication Process
•2 sides of DNA molecule unwind and separate; like
a zipper
•new nitrogen bases floating in nucleus pair up with
exposed bases
•A with T & C with G
•continues until both sides are complete; two new
molecules are exactly like the original!
•Cell can now proceed with cell cycle
Chapter 2 Section 4
CANCER
What is Cancer?
a disease in which cells grow and divide
uncontrollably, damaging parts of the body
around them
100’s of types of cancer
How cancer begins
something damages a portion of DNA in achromosome
mutation = a change in DNA
disrupts the cell cycle, causing cells to divide in an
uncontrolled way
CANCER
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2. How Cancer Spreads
a. tumor = a mass of abnormal cells that
develops when cancerous cells divide and
grow uncontrollably
b. some cancerous cell break off and enter
the bloodstream
Lung Cancer!
CANCER
3. Treating Cancer
 surgery can be used if the cancer has not spread
 radiation (high-energy beams) may be used on
fast-growing cancers
 chemotherapy (using drugs to kill cancer) is
effective because it can spread throughout the
body
 all treatments can have serious side effects, so
scientists are always looking for new treatments
CANCER
4. Cancer Prevention
 a. 2/3 cancer deaths are due to tobacco or
unhealthy diet