Transcript Chapter 10 Mitosis

10.1 Cell Growth
• Living things grow because it produces
more and more cells.
• Are the cells of an adult larger than the
cells of a baby?
NO!!! Adults just have more cells
than babies do.
Limits to Cell Growth
• Volume increases faster than surface area
• The larger a cell becomes, there are more
demands put on that cell. “DNA overload.”
– Nutrients and waste have a hard time going in
and out of the cell.
Hammond population and highways
Ratio of Volume to Surface Area
Surface area= (length x width x 6) cm2
Volume= (length x width x height) cm3
Ratio of volume S.A. to Volume= SA/ Volume
What happens when a cells gets
too large?
• Cell division- process whereby the cells
divide into two daughter cells
• Before the cell divides all the DNA is
copied.
• Each new daughter cells gets its own
“genetic library” they each get all the DNA.
10.2 Cell Division
• Process in which the cell divides into two
daughter cells. Each has the same exact
information as the original cell.
– Before cell division occurs the cell must
replicate or copy all its DNA.
– Solves the problem of DNA overload by
dividing (reduces the cell’s volume)
– Allows efficient exchange of materials with
the environment.
Chromosomes
• Structures found in the nucleus of a cell
that contain genetic information.
• Human cells have 46 chromosomes
• 23 chromosomes from mom
• 23 chromosomes from dad
Make up of a chromosome
• A chromosome is composed
of two
.
identical chromatids attached by a
centromere. Each chromatid is made up
of tightly wound DNA wrapped around
histones.
Chromosomes
• DNA coils around a special protein called
a HISTONE.
• DNA and HISTONE make
up NUCLEOSOMES.
Cell Cycle
• A cell grows, prepares for division, and
divides to form two daughter cells…each
of which repeat the cycle again.
• From One mitosis to the next mitosis
• Interphase, Cell division (mitosis),
cytokinesis
Interphase
•
•
•
•
G1=cell growth
S phase= DNA is replicated
G2=cell prepares for mitosis
Kind of like intermission…can’t really see
this happening, but happens behind the
scene.
Interphase
Mitosis
• Process in which the nucleus of a cell divides.
• Divided into four phases
– Prophase-1st, longest phase. Chromatin
condenses and chromosomes become visible.
– Metaphase-2nd phase (shortest) chromosomes
line up at center of cell
– Anaphase-3rd phase chromatids split and separate
to opposite poles
– Telophase-4th phase. Almost two new cells, but
not completely separated.
Mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
• The cytoplasm pinches in half. Each
daughter cell has an identical set of
duplicate chromosomes.
Fine TUNING what you’ve
learned.
• http://www.youtube.com/watch?v=ODwt6
OdN-8Y
10.3 Regulating the Cell Cycle
• Cyclin Protein Regulators- regulate the
timing of the cell cycle.
– Internal Regulators- make sure that mitosis
has waited for chromosomes to replicate all
the DNA.
– External Regulators- speed up or slow down
mitosis.
Cancer
• Uncontrolled cell growth is called cancer
• Most healthy cells will stop dividing when
they come into contact with one another.
• Cancer cells do not stop when touch
another cell. Grows until the nutrient
supply is gone.
Cancer
What do cells do incase of injury?
• Cells rush to the cite of the wound and
rapidly divide.
• They start to slow down when they get
close to each other.
• When do they stop?
– When they touch one another…
– At this time…you most likely have a scab.
On that note…we are done with this chapter. 