2. The larger the cell becomes, the more demands
the cell places on its DNA and the more trouble
the cell has moving enough nutrients and wastes
across the cell membrane.
DNA "Overload" – In time as the cell grows larger;
the DNA can no longer serve its increasing needs
Volume increases faster than the surface area
of a growing cell
Surface Area- to- Volume Ratio
The surface area-to-volume will decrease.
(causes problems)
3. So, surface area to volume is why the cells of
an organism do not grow larger even though
the organism grows much larger and why cells
stay small.
2 Basic Types of Reproduction
To stay small, cells must reproduce.
Asexual reproduction
one parent; offspring is identical to parent
Sexual reproduction
two parents; offspring is not identical to
parents
4. Copyright Pearson Prentice Hall
In eukaryotes, cell division occurs in two major
stages.
The first stage, division of the cell nucleus, is
called mitosis.
The second stage, division of the cell cytoplasm, is
called cytokinesis.
Cell Division
7. Copyright Pearson Prentice Hall
Chromosomes
Each chromosome
consists of two identical
“sister” chromatids.
Each pair of chromatids
is attached at an area
called the centromere.
Sister chromatids
Centromere
8. Copyright Pearson Prentice Hall
Chromosomes
When the cell divides, the chromatids
separate.
Each new cell gets one chromatid.
9. Copyright Pearson Prentice Hall
The Cell Cycle
Cell Cycle
The cell cycle is the series of events that cells go
through as they grow and divide.
Interphase is the period of growth that occurs
between cell divisions.
10. Copyright Pearson Prentice Hall
The Cell Cycle
During the cell cycle:
• a cell grows
• prepares for division
• divides to form two daughter cells, each
of which begins the cycle again
11. Copyright Pearson Prentice Hall
The Cell Cycle
The cell cycle consists of four phases:
• G1 (First Gap Phase)
• S Phase
• G2 (Second Gap Phase)
• M Phase
13. 2N
diploid cell –Two copies of each
chromosome. Where do the two
copies come from????
Mitosis Summary
(IPMAT)
2N
2N
2 identical diploid
daughter cells formed
14. Copyright Pearson Prentice Hall
Mitosis
Mitosis
Biologists divide the events of mitosis
into four phases: (PMAT)
• Prophase
• Metaphase
• Anaphase
• Telophase
16. Copyright Pearson Prentice Hall
Section 10-2
Prophase
Spindle
forming
Chromosomes
(paired
chromatids)
Centromere
Click to Continue
Mitosis
Prophase
17. Copyright Pearson Prentice Hall
Mitosis
Prophase
Prophase is the first and
longest phase of mitosis.
The centrioles separate
and take up positions on
opposite sides of the
nucleus.
Spindle
forming
Centromere
Chromosomes
(paired
chromatids)
18. Copyright Pearson Prentice Hall
Mitosis
The centrioles lie in a
region called the
centrosome.
The centrosome helps
to organize the spindle,
a fanlike microtubule
structure that helps
separate the
chromosomes.
Spindle
forming
Centromere
Chromosomes
(paired
chromatids)
19. Copyright Pearson Prentice Hall
Mitosis
Chromatin condenses
into chromosomes.
The centrioles separate
and a spindle begins to
form.
The nuclear envelope
breaks down.
Spindle
forming
Centromere
Chromosomes
(paired
chromatids)
20. Copyright Pearson Prentice Hall
Centriole
Centriole
Spindle
Mitosis
Click to Continue
Metaphase
Metaphase
21. Copyright Pearson Prentice Hall
Mitosis
Metaphase
The second phase of
mitosis is metaphase.
The chromosomes line
up across the center of
the cell.
Microtubules connect
the centromere of each
chromosome to the
poles of the spindle.
Centriole
Spindle
23. Copyright Pearson Prentice Hall
Mitosis
Anaphase
Anaphase is the third
phase of mitosis.
The sister chromatids
separate into individual
chromosomes.
The chromosomes
continue to move until
they have separated into
two groups.
Individual
chromosomes
25. Copyright Pearson Prentice Hall
Mitosis
Telophase
Telophase is the
fourth and final phase
of mitosis.
Chromosomes gather
at opposite ends of the
cell and lose their
distinct shape.
26. Copyright Pearson Prentice Hall
Mitosis
A new nuclear envelope
forms around each cluster
of chromosomes.
28. Copyright Pearson Prentice Hall
Cytokinesis
During cytokinesis, the
cytoplasm pinches in
half.
Each daughter cell has
an identical set of
duplicate chromosomes
29. Copyright Pearson Prentice Hall
Cytokinesis in Plants
In plants, a structure known as the cell plate forms
midway between the divided nuclei.
Cell wall
Cell plate
30. Copyright Pearson Prentice Hall
(must have QuickTake software installed on the
computer you are using for this presentation)
- or -
10-2
31. Copyright Pearson Prentice Hall
10-2
The series of events that cells go through as
they grow and divide is called
a. the cell cycle.
b. mitosis.
c. interphase.
d. cytokinesis.
32. Copyright Pearson Prentice Hall
10-2
The phase of mitosis during which the
chromosomes line up across the center of the
cell is
a. prophase.
b. metaphase.
c. anaphase.
d. telophase.
33. Copyright Pearson Prentice Hall
10-2
Cytokinesis usually occurs
a. at the same time as telophase.
b. after telophase.
c. during interphase.
d. during anaphase
34. Copyright Pearson Prentice Hall
10-2
DNA replication takes place during the
a. S phase of the cell cycle.
b. G1 phase of the cell cycle.
c. G2 phase of the cell cycle.
d. M phase of the cell cycle.
35. Copyright Pearson Prentice Hall
10-2
During mitosis, “sister” chromatids separate from
one another during
a. telophase.
b. interphase.
c. anaphase.
d. metaphase.
38. Copyright Pearson Prentice Hall
Controls on Cell Division
Controls on Cell Division
Experiments show that normal cells will
reproduce until they come into contact with
other cells.
When cells come into contact with other cells,
they respond by not growing.
This demonstrates that controls on cell growth
and division can be turned on and off.
39. Copyright Pearson Prentice Hall
Cell Cycle Regulators
The cell cycle is regulated by a specific
protein.
The amount of this protein in the cell rises
and falls in time with the cell cycle.
Scientists called this protein cyclin because
it seemed to regulate the cell cycle.
40. Copyright Pearson Prentice Hall
Uncontrolled Cell Growth
Uncontrolled Cell Growth
Cancer is a disorder in which some of the
body's own cells lose the ability to control
growth.
How are cancer cells different from
other cells?
41. Copyright Pearson Prentice Hall
Uncontrolled Cell Growth
Cancer cells do not respond to the
signals that regulate the growth of
most cells.
42. Copyright Pearson Prentice Hall
Uncontrolled Cell Growth
Cancer cells divide uncontrollably and
form masses of cells called tumors
that can damage the surrounding
tissues.
Cancer cells may break loose from
tumors and spread throughout the
body, disrupting normal activities and
causing serious medical problems or
even death.
43. Copyright Pearson Prentice Hall
10-3
The cell cycle is believed to be
controlled by proteins called
● spindles.
● cyclins.
● regulators.
● centrosomes.
44. Copyright Pearson Prentice Hall
10-3
Proteins that respond to events
inside the cell are called
● internal regulators.
● external regulators.
● cyclins.
● growth factors.
45. Copyright Pearson Prentice Hall
10-3
Once a multicellular organism
reaches adult size, the cells in its
body
● stop dividing.
● grow and divide at different rates,
depending on the type.
● have the same life span between cell
divisions.
● undergo cell division randomly.
46. Copyright Pearson Prentice Hall
10-3
One effect of an internal regulator is
that a cell will not begin mitosis until
● it becomes too large.
● the cell’s growth is stimulated.
● it is in physical contact with other cells.
● all its chromosomes have been replicated.
47. Copyright Pearson Prentice Hall
10-3
One factor common to almost all
cancer cells is
● a lack of cyclin.
● a defect in gene p53.
● exposure to tobacco smoke.
● exposure to radiation.
