Transcript Ch 10: Cell Growth and Division

10.1 Pre-Read Questions
1. Name 2 limitations to cell
growth.
2. How does DNA limit cell
growth?
3. Why is the ratio of surface
area to volume important?
4. Describe the process of cell
division.
Ch 10: Cell Growth and Division
10.1: Cell Growth
Cells
 Does not continue to
grow bigger
 Cells just continue to
produce more cells
Limits to Cell Growth
 2 main reasons
1.Larger a cell
becomes, the more
demands the cell
places on its DNA
Limits to Cell Growth
 2 main reasons
2. Cell has more trouble
moving enough
nutrients and wastes
in and out of cell
Reason #1 DNA “overload”
 DNA = information that
controls a cell’s function
 if cells grow, DNA does not
make extra copies
 DNA would not be able to
serve the needs of the cell
Reason #2: Exchanging Materials
 how fast materials leave
or enter the cell depends
on surface area
 food and oxygen depend
on cell volume
Ratio of Surface Area to Volume
 as surface area
increases, its volume
increases at a faster
rate
Ratio of Surface Area to Volume
Consequence = cells have
a more difficult time to
move needed materials in
and waste products out
Cell Division
 how cells reproduce
 one cell divides into
2 new cells
 daughter cells
Cell Division
before cell division cell copies DNA
Each daughter cell
gets own copy of DNA
10.2A
12 / 5 / 06
2 Stages
1. Mitosis = division of the
cell nucleus
2. Cytokinesis = division of
the cytoplasm
Mitosis
 asexual
 source of new cells
Chromosomes
 carries the genetic
information
 consists of DNA
 cells have specific
number of chromosomes
Chromosome
 not visible until cell
division
 replicated before cell
division
 chromosomes change
form to chromatids
Chromatids
 Separate from each
other and go into
daughter cells
 attached at a centromere
 located near the middle
of the chromatids
Centromere
Chromatid
Cell Cycle
 cell reproduction
 forms two daughter
cells
 in between period =
interphase
Cell Cycle: 4 phases
 consists of 4 phases
 M phase = mitosis and
cytokinesis
 S phase = chromosome
replication (S = synthesis)
 G1 and G2 (G = gap) -growth and activity
Interphase
 3 of the 4
phases occur
G1
 S phase
G2
G1 Phase
 cell growing
 increase in
size and
synthesize
new proteins
and
organelles
S Phase
 chromosome
replication
 proteins
synthesized
G2 Phase
 DNA
replication
complete at
beginning
 shortest
phase
G2 Phase
 organelles
produced
 prepare for
cell division
10.2 Post Read Questions
1. Describe the 2 stages of cell
division.
2. Draw a chromosome and
label and describe its parts.
3. What are the different
phases of interphase?
Describe each one.
4. What is the cell cycle?
10.2 B
12 / 06 / 06
QuickTime™ and a
Cinepak decompressor
are needed to see this picture.
Interphase
 In between periods of cell division
 Cell growth and DNA replication occur
Prophase
 first and longest phase (50%60%)
 chromosome becomes visible
 centrioles take position on
opposite sides of nucleus at
the centrosome
Prophase
 Centrioles lie in centrosome so
they can organize the spindle
 Spindle = fanlike microtubule
structure that helps separate the
chromosomes
Prophase
 end = chromosomes coil and
nuclear envelope break down
Metaphase
 lasts only a few minutes
 chromosomes line up
across the center of the cell
Metaphase (cont)
 microtubules connect the
centromere of each
chromosome to the two poles
of the spindle
Anaphase
 centromeres that join the
sister chromatids split into
individual chromosomes and
are moved apart to opposite
poles
Telophase
 chromosomes become dense
material
 spindle breaks apart
 nucleolus appears
Cytokinesis
 Division of cytoplasm
 usually occurs the same time
as telophase
 Animal Cell = cell membrane
draw inward and pinched off
 Plant cell = cell plate forms
midway between the 2 nuclei;
cell wall appears
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Put the
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ANSWER
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Ch 10 Review Questions (Cont)
1. What is cytokinesis? When does it
occur?
2. Compare how cytokinesis works
between animal and plant cells.
3. Describe metaphase.
4. Describe anaphase.
5. If you were to look at a picture of
telophase and anaphase, how can you
distinguish the difference between the
two?
10.3
12 / 7 / 06
Review: Cell Cycle
 Preparing for Cell
Division
 INTERPHASE
 G1
S
 G2
Review: Cell Cycle
 Steps of Cell Division
 Mitosis
 Prophase
 Metaphase
 Anaphase
 Telophase /
Cytokinesis
 Look at Figure 10.7
 Observe what is going on
 What is happening in
each step?
Cyclin
 protein
 regulates the timing
of the cell cycle in
eukaryotic cells
Regulatory Proteins
 Two types
1.Internal Regulators
2.External Regulators
Internal Regulators
 proteins that respond to
events inside the cell
 signals cell cycle to
continue ONLY WHEN
OTHER THINGS ARE
COMPLETE
External Regulator
 proteins that respond to
events outside the cell
 direct cells to speed up or
slow down the cell cycle
 example: growth regulators
Uncontrolled Cell Growth
 Cancer
 body loses ability to control
growth
 does not respond to the
regulator proteins
 result = large masses of cells
Tumors
masses of cells
 damages the surrounding
tissues
 cells break off and spread
throughout the body
Cause of cancer
 brought on by smoking
tobacco
 radiation exposure
 viral infection
 etc
10.3 Review Questions
1. Why is it important for cells to have
regulated cell growth?
2. What is the purpose of the protein
cyclin?
3. Compare and contrast internal
regulators and external regulators.
4. What is cancer? What causes
cancer?