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Warm Up
Beach Ball Activity
CHAPTER 10
Cell Growth and Division
10.1
Cell Growth
Why do cells divide?
Large cells have difficulty transporting
enough nutrients across their membrane
Cells are limited in size by their
–
surface to volume ratio
Cell Division
Process where a cell splits into two
Occurs in two main phases:
– Mitosis – division of nucleus
– Cytokinesis – division of cytoplasm
Chromosomes
Mother Cell
Made of DNA
– Contains the cells genetic code
Found in the nucleus
Each chromosome has a
matching pair (homologous)
Number depends on organism
Daughter Cells
Cell Cycle
Interphase (longest phase)
– G1 - first growth (gap) phase
– Synthesis - DNA makes a copy
– G2 - second growth (gap) phase,
preparing for mitosis
Mitosis - nucleus divides, ensuring each new cell
has the exact number of chromosomes as parent
Warm Up2 Reasons why cells divide rather than
continue to grow larger
Chapter 10
Mitosis Overview
Interphase
Interphase
– Chromosome are
replicated
– Chromosomes appear as
threadlike coils
(chromatin)
– Each chromosome and its
copy change to sister
chromatids at the end of
this phase
Chromosome
Sister Chromatids
Centromere
Mitosis
Prophase:
– Mitosis begins (cell begins to divide
centrioles appear and move to end of poles)
– Spindle fibers form between poles
– Nuclear membrane starts to disintegrate
Mitosis
Metaphase– Sister Chromatids (or pairs of
chromosomes)meet in the
middle and attach to the spindle
fibers at the centromere
Mitosis
Anaphase– Chromatids (or pairs of
chromosomes)
separate
– Begin to move away
from each other to the
poles of the cell
Sister Chromatids being
ripped apart
Mitosis
Telophase– Two new cells form
– Nuclear envelope
develops
– Chromosomes
begin to disperse
– Mitosis ends
Cytokinesis
Cell membrane
moves inward to
create two new
cells
– Each with its own
nucleus and
identical DNA.
Warm UP – Tues. 3/12
What is the acronym we used to
remember the four phases of mitosis?
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?
Warm Up – Oct. 8th
Phase of mitosis
(in order)
Acronym
What happens
(short description)
Chapter 10
Section 3: Regulating the Cell
Cycle
Controls on Cell Division
If cells are placed on
petri dish will grow
until they touch
something
– Edge of dish
– Other cells
Will grow again if cells
are removed
– Shows growth can be
turned on or off
Skin grafting
http://www.youtube.com/watch?v=pvbxm
m9inoo
Cell Cycle Regulators
Cyclins:
– Proteins that regulate
the timing of the cell
cycle
Two types:
– Internal regulators
– External regulators
Regulators
Internal Regulators:
– Internal events must take
place before the cell cycle
will proceed
All chromosomes must
be replicated before
mitosis occurs
Anaphase cannot
happen until all
chromosomes are
attached to spindle
fibers
Regulators
External Regulators:
– Tell cell to slow down or
speed up
– Called growth regulators:
Important during
embryonic
development and
wound healing
Uncontrolled Cell Growth
Cancer:
– Uncontrolled cell
growth
– Form masses called
tumors
– Damage surrounding
tissue
– Can break loose and
travel through body
Uncontrolled Cell Growth
Causes:
– Smoking
– Radiation
exposure
– Viral infections
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http://www.youtube.com/watch?v=YvpFJ6QEYdU&
safety_mode=true&persist_safety_mode=1
Uncontrolled Cell Growth
Gene p53 is linked to
many cancers
– Normally will not let
cell divide until all
chromosomes have
divided
– Defective in cancer
cells
Stem cells
Stem cells – unspecialized cells that have
the potential to differentiate
– Early embryonic development
produce every tissue in body
– Adults
In bone marrow
– Produce more than a dozen types of blood cells
Warm Up – Wed. 3/13
What is the name of the proteins that regulate the timing of
the cell cycle called?