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Intro to topic 3
Notes
There are 2 reasons cells divide
rather than grow indefinitely.
1. The larger that cells become,
the more demand the cell places
on the DNA
2. the large the cell becomes the
more trouble the cell has moving
enough nutrients and wastes across
the cell membrane
Cell division is
The process of DNA replication and the
division of the cytoplasm to form 2 new
identical cells
Cell division reduces the volume, and
increases the ratio between volume and
surface area.
you will need to be able to calculate surface area, volume
and the ratio of surface area to volume
http://www.youtube.com/watch?v=pv_RWaADwk&feature=related&safety_mode=true&pe
rsist_safety_mode=1&safe=active
Hw: Do Worksheet on cell growth
Cell Division
Chromosomes are not visible in most cells,
except during ________________
Cell division
When chromosomes
become visible they
consist of
_________________
2
sister chromatids
_________________
connected
at the
_________________
centromere
_____
Each pair of chromatids is attached
at an area called the
centromere
___________________________
The Cell Cycle is diagramed below:
The period of growth between cell divisions is
called
Interphase
______________________________
The division of the nucleus during
the M phase of the cell cycle is
called ___________________.
Mitosis
Interphase is divided into 3
phases
G1 Phase
____________________
S Phase
_____________________
G2 Phase
____________________
During the G1 phase ________________________
Rapid growth
Replication of Chromatids
During the S phase ___________________
for mitosis
During the G2 phasePrep
_________________________
(make another centriole)_
The 4 phases of Mitosis are:
1. Prophase -- Chromosomes become
visible, nucleus and nucleolus dissolve.
Centrioles move to opposite ends and
form microtubules( spindle)
.
Chromosomes
Centrioles
Microtubles/ spindle
2. Metaphase -- Chromosomes line
up across the middle of the cell
Microtubles/ spindle
Chromosomes
Centrioles
3. Anaphase -Chromosomes migrate to
the 2 ends of the cell
centrioles
chromatids
4. Telophase -- New
nuclear membrane forms,
and the cell begins to
divide by cytokinesis.
prophase
chromosomes
Interphase
spindle
centriole
Metaphase
Nuclear membrane
anaphase
Cell membrane
nucleolus
centrioles
telophase
chromosomes
Two new daughter cells
chromosomes
In animal cells
Centrioles
_______________________
located near
the nucleus help separate the chromosomes
Spindle fibers
by forming ________________________.
cytokinesis
_____________________ is the
process of the cytoplasm being
divided in two pieces.
Cell plate
In pant cells a _____________________
forms midway of the cell.
When an injury occurs the cells in
the area begin to
divide
____________________
When the injury is almost healed
__________________________
the rate of cell division slows
cyclins
__________________
are
responsible for regulating the cell
cycle.
Cancer is
unregulated cell growth
___________________________
______________
Cancer cells don’t respond to
signals that regulate
growth
___________
Cancer cells form masses of cells
tumors
called ___________________
Cancer cells break loose and
spread throughout the
body
___________________
Hw: 21 in workbook
worksheet