1. Chapter 10
Cell Growth and Reproduction

2. The Big Idea
• You are constantly changing
• Worn out cells get replaced
• Cuts and bruises heal
• 2-3 billion red blood cells get
replaced each second
• Muscles you exercise get larger

3. The Cell Cycle
Cell
Division
Preparing for
reproduction
Interphase
Growth and
Development

4. 10-1 Cell Growth

5. Q: When a living thing grows,
what happens to its cells?
A: Cells increase in number

6. There are two main reasons
why cells divide
1. The larger the cell becomes, the
more demands there are on the
DNA
2. The cell has trouble moving
enough nutrients and wastes
across the cell membrane

7. Division of a cell
• Before it gets too large, a growing
cell divides forming two daughter
cells
• The process by which a cell
divides into two new daughter
cells is called cell division

8. Daughter
cells

9. This solves the two problems
of a growing cell
1. The cell replicates all of its DNA
2. The actual division of the cell
decreases its volume

10. 10-2 Cell Division

11. In eukaryotes cell division
occurs in two main stages
1. Mitosis
2. Cytokinesis

12. Chromosomes
• In eukaryotic cells, the genetic
information that is passed on from
one generation to the next is
carried on
Chromosomes
___________________________

14. • Chromosomes are made of DNA –
which carries the cells coded
information – and proteins
• The cells of every organism have a
specific number of chromosomes
• You can’t see chromosomes except
during cell division, when they
condense and compact

16. • Before cell division, each chromosome
is replicated, or copied
• Because of this, each chromosome
consists of two identical
_______________________________
“sister chromatids”
• When the cell divides, the sister
chromatids separate and one
chromatid goes to each of the two new
cells
• Each pair of chromatids are attached
at an area called the centromere

17. Interphase
• “In-between” period of growth
between division

18. • During the cell cycle, a cell grows,
prepares for division, and divides
to form two daughter cells, each of
which then begins the cycle again
• The cell cycle consists of 4 phases
1. M phase
2. G1 phase
3. S phase
4. G2 phase

20. • G1 – Cells do most of their growing.
They increase in size and make new
proteins and organelles
• S – Chromosomes are replicated
• G2 – Organelles and molecules
required for cell division are produced
• M – cell divides

21. Prophase
• The chromatin
condenses into
chromosomes
• The centrioles
separate
• A spindle begins to
form
• The nuclear
membrane breaks
down

22. Metaphase
• Chromosomes
line up down the
middle of the cell
• Each
chromosome is
connected to a
spindle fiber at
its centromere

23. Anaphase
• Centromeres
split, allowing
sister chromatids
to separate
• The
chromosomes
move to opposite
ends of the cell

24. Telophase
• Chromosomes
unwind
• A nuclear
membrane
reforms
• Nucleolus
becomes visable

25. Cytokinesis (In animals…)

26. Cytokinesis (In plants)
• A cell plate gradually develops
into a separating membrane
• A cell wall then begins to appear
in the cell plate

27. Golgi vesicles
move toward
equator
Early cell
plate
Cell Plate

28. The Big Picture!
• Mitosis is the division of a
nucleus
___________
• Mitosis produces two nuclei that
have the __________ number of
same
chromosomes as the original

29. (Before Mitosis)
46
46 46 (After Mitosis)

32. 10-3 Regulating the
Cell Cycle

33. Knowing When to Stop
•Suppose you had a paper cut on your
finger. Although the cut may have bled and
stung a little, after a few days, it will have
disappeared, and your finger would be as
good as new.
1. How do you think the body repairs an injury,
such as a cut on a finger?
2. How long do you think this repair process
continues?
3. What do you think causes the cells to stop
the repair process?

34. Controls on Cell Division

35. Controls on Cell Division
• When cells come into contact with
other cells, they respond by not
growing
• When an injury such as a cut occurs,
cells at the edges of the injury are
stimulated to divide rapidly, the cell
division stops when the healing
process is complete

36. The sample is injected
into a second cell in G2
of interphase.
A sample of cytoplasm is
removed from a cell in As a result, the
mitosis. second cell enters
mitosis.

37. Cyclins
• Protein that regulates the cell
cycle
• There are 2 types of regulatory
proteins; those that occur inside
the cell and those that occur
outside the cell.

38. Internal Regulators
• Allow the cell cycle to proceed
only when certain processes have
happened inside the cell
• Ex.) several regulatory proteins
make sure that a cell does not go
through mitosis until all
chromosomes have been
replicated

39. External Regulators
• Direct cells to speed up or slow
down the cell cycle
• Ex.) growth factors
• Molecules found on the surface of
neighboring cells often have the
opposite effect causing cells to
slow down or stop their cell cycles
• These signals prevent excessive
cell growth

40. Cancer
• A disorder in which some of the body’s
own cells lose the ability to control growth
• When cells divide uncontrollably, masses
of cells called tumors can damage the
surrounding tissues
• Cancer cells may break loose from the
tumors and spread throughout the body
*(DNA interactive DVD)*

41. Q: What causes the loss of
growth control?
A: smoking tobacco, radiation and chemical
exposure, viral infections
All cancers have one thing in common: The
control over the cell cycle has been
broken
• Some cancer cells will no longer respond
to external growth regulators
• Others fail to produce the internal
regulators

42. p53
• An astonishing number of cancer
cells have a defect in a gene
called p53
• p53 normally halts the cell cycle
until all the chromosomes have
been properly replicated
• if we could fix p53 we could cure
many forms of cancer

43. Is a cure in sight?
• Cancer is a serious disease
• As difficult as a cure would be, at
least scientists know where to start
• Cancer is a disease of the cell cycle ,
and conquering cancer will require a
much deeper understanding of the
processes that control cell division