1. The process of cell division occurs in a series of stages or phases!!!
Mitosis
The process of cell division occurs in a series of stages or phases!!!

2. Limited cell size (reason they must divide)
DNA “overload”
Instructions found in the nucleus are sufficient to meet all the cells’ needs
Exchanging Materials & Messages
All requirements must pass into the cell through the membrane and all wastes must pass out of the cell through the membrane
Surface Area-to-Volume Ratio
Want greater surface area compared to volume
Volume increases faster than does the surface area as a cell gets larger

3. Cell division accounts for three essential life processes:
Growth-happens because cells grow to a maximum size, then divide
Repair-repairing tissues only happens because of cell division
Repairing a tiny cut to regeneration of an arm on a sea star
Reproduction- asexual and sexual reproduction are dependent on cell division
Asexual, a whole new organism grows (mitosis)
Sexual, specialized cell division leads to production of egg and sperm cells allowing this to occur (meiosis)

4. Cell Cycle G1 = cell growth S = (synthesis) DNA replication
These three make up Interphase which is the longest part of the cell cycle
G1 = cell growth
S = (synthesis) DNA replication
G2 =some growth, preparation for mitosis
M = mitosis (not a part of interphase)
Cytokinesis

5. Interphase (G1, S, G2)
nucleolus
DNA starts as chromatin (long threads), but then winds up into chromosomes (coils) AFTER the copy is made. Each chromosome and its copy (sister) are attached and called sister chromatids at the end of this phase.
Area where the sister chromatids are joined.

6. Mitosis Cell Division
Prophase
Metaphase
Anaphase
Telophase

7. Prophase
Centrioles appear and begin to move to opposite ends of the cell.
Spindle fibers form between the centrioles.
Nuclear membrane starts to disappear.
Chromosomes condensed/nucleolus not visible.
Centrioles
Spindle fibers

8. Metaphase
Chromatids (or pairs of chromosomes) attach to the spindle fibers.
Centrioles are at poles.
Line up in middle

9. Anaphase
Chromatids separate and begin to be pulled to opposite ends of the cell.

10. Telophase Two new nuclei form Chromosomes just begin to unwind
Cytoplasm pinches inward

11. Cytokinesis
In animal cells, the cell membrane pinches inward to create two daughter cells – each with its own nucleus with identical chromosomes.
In plant cells, a structure known as the cell plate forms midway between the divided nuclei

12. Mitosis in Actual cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
has centrioles
centrosome
Animal Cell
at Interphase
aster
20 µm
duplicated
chromosome
20 µm
spindle
pole
9 µm
metaphase plate
chromosomes at
20µm
daughter chromosome
20µm
cleavage furrow
16µm
nuclear
envelope
fragments
centromere
kinetochore
nucleolus
MITOSIS
chromatin
condenses
nucleolus
disappears
spindle
fibers forming
spindle fiber
kinetochore
kinetochore
spindle fiber
polar spindle fiber
Metaphase
Centromeres of duplicated chromosomes
of fully formed spindle). Kinetochore spindle
are aligned at the metaphase plate (center
fibers attached to the sister chromatids
come from opposite spindle poles.
Telophase
Daughter cells are forming
as nuclear envelopes and
nucleoli reappear. Chromosomes will
become indistinct chromatin.
Early Prophase
Centrosomes have duplicated.
Chromatin is condensing into
chromosomes, and the nuclear
envelope is fragmenting.
Prophase
duplicated chromosomes are visible.
Nucleolus has disappeared, and
Centrosomes begin moving apart,
and spindle is in process of forming.
Prophase
duplicated chromosomes are visible.
Nucleolus has disappeared, and
Centrosomes begin moving apart,
and spindle is in process of forming.
Anaphase
Sister chromatids part and become daughter
chromosomes that move toward the spindle
poles. In this way, each pole receives the same
number and kinds of chromosomes as the parent cell.
centrosome
lacks centrioles
Plant Cell
at Interphase
25µm
cell wall
chromosomes
6.2µm
spindle pole lacks
centrioles and aster
20µm
spindle fibers
6.2µm
6.2µm
cell plate
6.6µm
Animal cell(Early prophase, Prophase, Metaphase, Anaphase, Telophase): © Ed Reschke; Animal cell(Prometaphase): © Michael Abbey/Photo Researchers, Inc.;
Plant cell(Early prophase, Prometaphse): © Ed Reschke; Plant cell(Prophase, Metaphase, Anaphase): © R. Calentine/Visuals Unlimited; Plant cell(Telophase): © Jack M. Bostrack/Visuals Unlimited;

13. Cell Cycle Control
Cells have very careful control over the cell cycle:
To maintain quality of cells
Uncontrolled growth is Cancer
Three environmental factors that cause cancer are:
cigarette smoke
air and water pollution
exposure to ultraviolet radiation from the sun AND TANNING BEDS!!!

14. The Cell Cycle Interphase S (growth and DNA replication) G1 checkpoint
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Interphase S
(growth and DNA
replication)
G1 checkpoint
Cell cycle main checkpoint.
If DNA is damaged, apoptosis
will occur. Otherwise, the cell
is committed to divide when
growth signals are present
and nutrients are available. G1
G2 checkpoint
Mitosis checkpoint.
Mitosis will occur
if DNA has
replicated properly.
Apoptosis will
occur if the DNA is
damaged and
cannot be repaired. G2
(growth and final
preparations for
division) G1
(growth) G0 M G2
Cytokinesis
elophase
Prophase
Anaphase
Metaphase
Late prophase T M
M checkpoint
Spindle assembly
checkpoint. Mitosis
will not continue if
chromosomes are
not properly aligned.

15. Apoptosis
Programmed cell death
Like the cell is committing suicide

16. Characteristics of Cancer Cells
Lack differentiation
Are nonspecialized
Are immortal (can enter cell cycle repeatedly)
Have abnormal nuclei
May be enlarged
May have abnormal number of chromosomes
Extra copies of genes
Form tumors
Mitosis controlled by contact with neighboring cells – contact inhibition
Cancer cells have lost contact inhibition

17. Characteristics of Cancer Cells
Undergo metastasis
Original tumor easily fragments
New tumors appear in other organs
Undergo angiogenesis
Formation of new blood vessels
Brings nutrient and oxygen to tumor

18. Progression of Cancer
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
New mutations arise, and one cell (brown) has the ability to start a tumor.
primary tumor
lymphatic
vessel
blood
vessel
Cancer in situ. The tumor is at its place of origin. One cell (purple)
mutates further.
lymphatic
vessel
blood
vessel
Cancer cells now have the ability to invade lymphatic and blood vessels
and travel throughout the body.
New metastatic tumors are found some distance from the primary tumor.

19. Origins of Cancer: Oncogenes
Mutations in DNA repair mechanisms
Oncogenes
Proto-oncogenes (when they are healthy) promote the cell cycle in various ways
Tumor suppressor genes inhibit the cell cycle in various ways
Both normally regulated in coordination with organism’s growth plan
If either mutates, may lose control and become oncogene (either one).

20. Origins of Cancer: Telomerase
Chromosomes normally have special material at each end called telomeres (end parts)
These get shorter each cell division
When they get very short
The cell will no longer divide
Almost like running out of division tickets
Telomerase is an enzyme that adds telomeres
Mutations in telomerase gene:
Keeps adding new telomeres
Allow cancer cells to continually divide
Like counterfeit tickets

21. d: © Biophoto Associates/Photo Researchers, Inc.
Causes of Cancer
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Heredity
Radiation
sources
growth
factor
growth factor
Activates signaling
proteins in a stimulatory
pathway that extends
to the nucleus.
Viruses
receptor
protein
Pesticides
and
herbicides
oncogene P
a. Influences that cause mutated proto-oncogenes
(called oncogenes) and mutated tumor
suppressor genes P
activated
protein
signaling P
protein
signaling
Stimulatory
pathway
phosphate
gene product
promotes
cell cycle
b. Effect of growth factor
Inhibitory
pathway
gene product
inhibits
cell cycle
proto-oncogene
Codes for a growth factor,
a receptor protein, or a
signaling protein in a
stimulatory pathway.
If a proto-oncogene
becomes an oncogene,
the end result can be
active cell division.
c. Stimulatory pathway and
inhibitory pathway
tumor suppressor gene
Codes for a signaling
protein in an inhibitory
pathway. If a tumor
suppressor gene mutates,
the end result can be
active cell division.
d. Cancerous skin cell
1,100X
d: © Biophoto Associates/Photo Researchers, Inc.

22. Animation Cyclin- any gene involved in regulating the cell cycle.
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23. Normal cells obey strict rules. Divide only when told.
Die rather than misbehave.
~Dr. Andrew Murray
Harvard University

24. If only students were like “normal cells”.
~Dr. Tracey Schneeman
Streetsboro High School

25. Stem Cells ADULT STEM CELLS Many mammalian organs contain stem cells
Retain the ability to divide
Aren’t totally differentiated (specialized)
bone marrow stem cells divide to produce various types of blood cells
EMBRYONIC STEM CELLS
Have the ability to become ANY type of cell
Currently controversial

26. Therapeutic cloning to produce human tissues can begin with either adult stem cells or embryonic stem cells
Embryonic stem cells can be used for reproductive cloning, the production of a new individual

28. Prokaryotic Cell Division
Prokaryotic chromosome is a ring of DNA
1,000 X length of cell
Replicated into two rings prior to division
Replicate rings attach to plasma membrane
Binary fission
Splitting in two between the two replicate chromosomes
Produces two daughter cells identical to original cell – Asexual Reproduction

29. Binary Fission of Prokaryotes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
chromosome
1. Attachment of chromosome to
a special plasma membrane
site indicates that this
bacterium is about to divide.
cell wall
plasma
membrane
cytoplasm
2. The cell is preparing for binary
fission by enlarging its cell wall,
plasma membrane, and overall
volume.
200 nm
3. DNA replication has produced
two identical chromosomes.
Cell wall and plasma mem-
brane begin to grow inward.
200 nm
4. As the cell elongates, the
chromosomes are pulled apart.
Cytoplasm is being distributed
evenly..
5. New cell wall and plasma
membrane has divided the
daughter cells.
200 nm
(All): © Stanley C. Holt/Biological Photo Service.

31. January 30, 2008
Do you think all cells continue to cycle through mitosis throughout the entire life of a person? Are there any cells that you think do? Name them. Are there any cells that you think do not? Name them. (4 points)