Transcript Cell Growth & Division - Northwest Allen County Schools

Chapter 10
Chapter 10 – Things You Will be Able to Do:
•Name
2 reasons
why cells divide.
Why are
cells
so small?
•Describe what problem cell growth causes for cell
efficiency
and homeostasis.
1. DNA
“Overload”
•Name the main events of the cell cycle.
- Large
can’t get
the
from
its DNA
•Describecells
what happens
during
theinfo
4 phases
of mitosis.
•Recognize, name and explain the various stages of the
to
ribosomes far away from(G1,
the
nucleus.
cell cycle including interphase
S, G2 ) and the
M phase or
division(mitosis
and cytokinesis).
2. Difficult
tocell
exchange
materials
•Recognize and name the phases of mitosis on prepared
slides
and incells,
digital imagery.
- In
large
many organelles would be too
•Identify a factor that can stop cells from growing.
far from
the
cell
membrane,
thus they
•Describe
how
the cell
cycle is regulated.
•Explain
cancerto
cells
are nutrients
different from normal
would
be how
unable
get
or getcells.
rid of
• List 3 causes (carcinogens?) of cancer.
theirDescribe
waste.
how cells become specialized (differentiate) for
different functions.
Why is the surface area (SA) to Volume (V) ratio
(SA/V) so important?
1.
2.
It is a mathematical way to express the
exchanging materials dilemma.
Cells require a large SA to Volume ratio.
- the surface area must be a lot larger
than the volume
As a cell grows, its volume increase much
more rapidly than it surface area
- this makes the SA/V smaller
How big can a cell get?
About twice its original size.
What does it do when it reaches this size?
Divide into two “daughter cells”
- this process is called cell division
Step 1: DNA Replication & Division
(each new cell gets a complete
copy of the DNA)
Step 2: Fission (the action of
dividing or splitting something into two or
more parts )
What is the difference between asexual & sexual
reproduction?
Asexual – one parent
- offspring is genetically identical to
the parent
- easier to do, but there is a lack of
genetic variety
Sexual – two parents
- offspring is genetically different from
the parents
- harder to do, but offers much more
genetic variety (genetic variety is the
raw material for evolution)
Chapter 10 – Things You Will be Able to Do:
Prokaryotic
Chromosomes:
•Name 2 reasons why cells divide.
what
problem cell
growth causes
for cellof DNA
1. Only•Describe
contain
a single,
circular
molecule
efficiency and homeostasis.
called
a nucleoid
•Name
the main events of the cell cycle.
what happens during the 4 phases of mitosis.
2. They•Describe
also
have
other
small
pieces
of
DNA
called
•Recognize, name and explain the various stages of the
plasmids.
cell cycle including interphase
(G1, S, G2 ) and the
M phase or cell division(mitosis and cytokinesis).
•Recognize and name the phases of mitosis on prepared
slides and in digital imagery.
•Identify a factor that can stop cells from growing.
•Describe how the cell cycle is regulated.
•Explain how cancer cells are different from normal cells.
• List 3 causes (carcinogens?) of cancer.
Describe how cells become specialized (differentiate) for
different functions.
Prokaryotic cell division is called
binary fission.
Step 1: DNA Replication
- Each of the 2 daughter cells will
have a complete set of DNA
Step 2: Fission
- The mother cell divides in two to
produce the two daughter cells.
Eukaryotic Cell Division:
Step 1: Mitosis
- This is the division of the nucleus
after DNA Replication.
- Each daughter cell will receive a
complete nucleus
- Has four phases (PMAT)
Step 2: Cytokinesis
- This is the division of the cell.
What is a chromosome?
- Condensed chains of DNA
- A cell’s DNA is usually divided into several
chromosomes
- The 3 billion base pairs that make up the DNA in
one of your cells is divided into 46 different
chromosomes.
Eukaryotic Chromosome Structure:
Chromosome Structure:
Has an “X” shape (when
duplicated)
2. Each side of the X is called
a sister chromatid.
3. Sister chromatids are held
together by a
centromere.
- centromeres are
basically protein
velcro.
4. Kinetochores are where
the mitotic spindle will
attach during mitosis
1.
Chromosome Structure:
the confusing part
1. Chromatin condenses
into chromosomes
2. Chromosomes are made
of chromatids.
3. When the chromatids
separate during mitosis,
they are called
chromosomes again.
They are all made of the
same stuff, just a
different name at
different times.
The Eukaryotic Cell Cycle:
Has Two Main Phases:
1.
Interphase
- The time between cell divisions
2. M Phase
- Mitosis & Cytokinesis occurs during this phase.
Interphase:
1. Growth Phase 1 (G1 Phase)
- Cell doubles its size
2.
Synthesis Phase (S Phase)
- DNA Replication occurs
3.
Growth Phase 2 (G2 Phase)
- Cell produces the
materials that will be used
during cell division
- The Centrioles replicate
- “Spell Checks” the DNA
to make sure it is ready
for cell division.
M Phase: the cell division phase & has two parts
A. Mitosis – division of the nucleus
The 4 Mitotic Phases:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
B. Cytokinesis – starts during Telophase
The Mitotic Phases:
1.
Prophase
- Chromatin condenses
into chromosomes.
- The nuclear envelope
begins to break down.
- Centrioles begin to
move towards the
poles.
- The mitotic spindle
begins to form.
The Mitotic Phases:
2.
Metaphase
- The chromosomes line
up on the cell’s
equator.
- The nuclear envelope is
gone.
- Centrioles are at the
poles.
- The spindle is complete
and attached to the
kinetochores.
The Mitotic Phases:
3.
Anaphase
- The centromeres separate
& the chromatids become
individual chromosomes.
- The kinetochores drives the
movement toward the
centrioles.
- Chromosomes move all
the way to the poles.
The Mitotic Phases:
4.
Telophase
- Basically the
opposite of the
Prophase.
- Chromosomes
uncoil.
- Nuclear Envelope
reforms.
- Spindle breaks
down.
Cytokinesis:
1.
Occurs during Telophase.
2. The actual division of the cytoplasm into two
daughter cells.
Animal Cells:
1.
Starts with the formation of the cleavage furrow.
2. Cleavage furrow pinches in until the cells are
separated.
Plant Cells:
1.
Starts with the formation of the cell plate along the
cell’s equator.
2. Cell plate will form a cell wall between the two cells.
How often can cell divide?
About 50 times. This is known as the Hayflick
limit.
How does this happen?
Think of your chromosomes as a shoestring with
the plastic end. The ends on the chromosomes are
called telomeres and they keep the DNA from
unraveling. After about 50 cell ÷, the telomeres are
too short to withstand anymore.
Chapter 10 – Things You Will be Able to Do:
2 reasons why cells divide.
How is •Name
the
cell
cycle controlled in multicellular
•Describe what problem cell growth causes for cell
organisms?
efficiency and homeostasis.
•Name the
main events of the cell cycle.
1. Contact
Inhibition
•Describe what happens during the 4 phases of mitosis.
- Cells
willname
divide
untilthe
the
are stages
touching
•Recognize,
and explain
various
of the
cell cycle including
interphase
another
cell on
all sides. (G1, S, G2 ) and the
M phase or cell division(mitosis and cytokinesis).
2. Internal
& and
External
Growth
Factors
•Recognize
name the phases
of mitosis
on prepared
and in digital
imagery. the timing of the cell
A.slides
Cyclins
– control
•Identify a factor that
can stop cells from growing.
cycle
•Describe how the cell cycle is regulated.
B.•Explain
Internal
Regulators
– afrom
type
of cells.
quality
how cancer
cells are different
normal
• List 3 causes (carcinogens?) of cancer.
control
Describe how cells become specialized (differentiate) for
C.different
External
functions.Regulators – many of these
are hormones
How is the cell cycle controlled in
multicellular organisms?
3. Apoptosis – a.k.a “programmed
cell death.”
- The cell basically self-destructs
by breaking into small pieces in a
process called “blebbing.”
- The pieces are then cleaned up
by white blood cells
- Apoptosis is often used in
development: apoptosis makes
the tail on a tadpole go away.
- Many cells have an “expiration
date” & then go through
apoptosis. Many cancers are
caused when these cells fail to
go through apoptosis.
Uncontrolled Cell Growth (cancer):
1.
Cancer cells do not respond to normal regulatory signals.
A mass of tumor cells is called a tumor.
2.
Their telomeres often do not get shorter after each ÷.
The Hayflick Limit doesn’t apply to them.
3.
The p53 gene is often involved. The p53 protein is the
spell checker of DNA Replication. A functional p53
recognizes mistakes and if they are severe enough, will
cause the cell to go through apoptosis (Programmed
Cell Death). When it malfunctions, mistakes
(mutations) remain and are passed on to the daughter
cells.
- The carcinogens in tobacco smoke have
been shown to directly damage the p53
gene.
What are stem cells?
They are undifferentiated or
unspecialized cells.
Types of embryonic stem cells:
1.
Totipotent – these stem cells
can develop into any type of
cell. Only the fertilized egg &
the first few cell made by the
early cell divisions are
totipotent.
2.
Pluripotent – these stem
cells are found in the inner
cells mass (ICM) of the
blastocyst. These cells can
turn into most of the 200+
different human cell types.
The ICM will become the
organism.
What are adult stem cells?
 These stem cells are found in
many organs.
 They are called multipotent
because they can only turn
into the cell of the various
tissues of the organ.