Transcript CHROMOSOMES

Image from: http://www.bcps.org/offices/lis/models/life/images/grow.JPG
CELL GROWTH
& DIVISION
10-1 & 10-2
Image by Riedell
DNA in PROKARYOTES
• BACTERIAL DNA is CIRCULAR
• HAVE ONE CHROMOSOME
• NO NUCLEUS;
ATTACHED TO CELL MEMBRANE
http://www.origin-life.gr.jp/3202/3202121/fig6.jpg
DNA in EUKARYOTES
(Plants & Animals)
• DNA is ROD-SHAPED CHROMOSOMES
• MANY PAIRS
• FOUND IN NUCLEUS
http://cellbio.utmb.edu/cellbio/chrom2.jpg
Chromosome structure
CHROMATIDS
• ___________________
2 identical arms
• __________________
CENTROMERE
constricted area
holds
chromatids together
HOMOLOGOUS
•__________________
PAIR
2 of each chromosome
(one from mom; one from dad)
HOMOLOGOUS CHROMOSOMES
• SAME SIZE
• SAME SHAPE
• CARRY GENES for the
SAME TRAITS
IDENTICAL
• BUT NOT
______________!
(Don’t have to have the
SAME CHOICES)
http://arnica.csustan.edu/biol3020/cell_division/cell_division.htm
http://sps.k12.ar.us/massengale/genetics%20tutorial.htm
CELL DIVISION in PROKARYOTES
Bacteria reproduce using
BINARY FISSION
__________________________________
http://fig.cox.miami.edu/~cmallery/150/mitosis/fission.jpg
CELL
CYCLE
______________ =
series of events that cells go
through as they grow and
develop
cells alive cell cycle
CELL CYCLE
INTERPHASE – non-dividing phase
G1- Grow bigger
Cell is “doing its job”
DNA is spread out as chromatin
S - Synthesis (copy DNA)
& chromosomal proteins
G2- Grow bigger, make organelles &
molecules needed for cell division
INTERPHASE: (IN between dividing)
Set up cell membrane on desk (Use black string to make a big oval on the desk).
DNA will switch back and forth between chromatin (long) and chromosomes
(short) pieces during the activity.
In interphase DNA is spread out as chromatin. Cells start with 6 chromosomes.
(Count out 3 long purple and 3 long green strings and place in center of cell)
Nuclear membrane is visible (Place pink yarn piece around the DNA)
During S phase DNA is copied. Hold up each chromatin yarn piece and place a
"copy" along side of it.
(Use the 3 extra long purple/green strings)
Replace DNA in nucleus
CELL DIVISION
MITOSIS – Nuclear division
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis – Cytoplasm divides
G0 – cell stops dividing
(Ex: nerve cell)
INTERPHASE (G1 - S - G2)
In between divisions
Cells are in this phase most of the time
Can see nucleus
DNA spread out as chromatin
Can’t see chromosomes
DNA gets copied (S)
Cell gets ready to divide
Pearson Education Inc publishing as Pearson Prentice Hall
PROPHASE
1st dividing phase
http://www.life.uiuc.edu/plantbio/102/lectures/08mit&veg102.html
DNA scrunches into chromosomes
Centrioles appear in centrosome region
& move to poles
Nuclear membrane & nucleolus disappear
Spindle fibers form & attach to
chromosomes
• PROPHASE: (First dividing phase- Pros are #1)
Chromatin condenses into chromosomes (Replace
longer yarn pieces in nucleus with shorter ones)
Remember to keep the chromatid "copies"
together.
Nucleus/nucleolus disappears. (Remove pink yarn
piece around chromosomes)
• Centrioles/Spindle appear (students play role of
spindle with their fingers)
CENTROSOME
________
region organizes spindle
Spindle MICROTUBULES are part of cytoskeleton
http://www.coleharbourhigh.ednet.ns.ca/library/organelle_worksheet.htm
METAPHASE
Chromosomes line up in
middle
___________
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG
METAPHASE (MIDDLE)
Chromosomes line up in middle of cell. {Spindle
(fingers) move chromosomes to middle of cell}
ANAPHASE
Centromeres split
apart
Centrioles pull chromatids_______
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www.science.siu.edu/plant-biology/PLB117/JPEGs%20CD/0247.JPG
ANAPHASE (APART)
Chromatid arms separate and move to opposite ends
of cell (Use fingers to separate chromatid arms)
TELOPHASE (reverse prophase steps)
two nuclei
See ______
Nuclear membrane & nucleolus return
Chromosomes spread out as chromatin
Centrioles disappear
Spindle fibers disappear
Images from:
Pearson Eduction Ince; Publishing as Pearson Prentice Hall
http://www2.bc.cc.ca.us/cnewton/Biology%2011/Mitosis.html
-Count chromosomes. You started with 6 (3 large,
medium, small purple & 3 large, medium, small
green)
-How many does your cell have now? (Should have
3 purple and 3 green; check to make sure you have
one L, M, S purple and one L, M, S, green)
CYTOKINESIS
Cytoplasm splits into 2 cells
ANIMAL CELLS pinch cytoplasm in two
with a ______________________
CLEAVAGE FURROW
CYTOKINESIS
Cytoplasm splits into 2 cells
PLANT CELLS can’t pinch because
they have a sturdy ____________
CELL WALL
Plant cells separate cytoplasm by
CELL PLATE
growing a _______________
down the middle.
http://www.eastcentral.edu/acad/depts/BI/plant_mitosis_nolabels.html
CYTOKINESIS (Cytoplasm splits)
Animal cells use a cleavage furrow.
(Have students push cell membrane together in
middle to make two cells)
Plant cells make a cell plate
(Have students use their orange string to make a wall
instead of pinching)
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Figure 10–5 Mitosis and Cytokinesis
Section 10-2
Spindle
forming
Centrioles
Nuclear
envelope
Chromatin
Interphase
Centromere
Chromosomes
(paired chromatids)
Prophase
Cytokinesis
Go to
Section:
Spindle
Centriole
Telophase
Nuclear
envelope
reforming
Centriole
Individual
chromosomes
Anaphase
Metaphase
Concept Map
Section 10-2
Cell Cycle
includes
is divided into
Go to
Section:
is divided into
Concept Map
Section 10-2
Cell Cycle
includes
Interphase
M phase
(Mitosis)
is divided into
is divided into
G1 phase
Go to
Section:
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase
10- 3
REGULATING the
CELL CYCLE
http://www.travel-net.com/~andrews/images/animations/traffic.gif
Control of Cell Division
If center cells are removed,
cells near the space will
start to grow again.
Cells grow until they
touch other cells
SHOWS: Cell division
genes can be turned on
and off
Section 10-3
10-7 Control of Cell Division
Why didn’t the cells keep dividing until they spilled over
the edge of the petri dish?
When the cells came into contact with other
cells, they responded by not growing.
What happened to the cells between the first petri dish and the second petri dish?
Cells divided until a thin layer of cells covered the bottom of the dish.
What caused the difference shown b/w the third and fifth petri dishes?
Cells began dividing again until they filled the empty space.
CELL DIVISION GENES
EXAMPLE: Cell division genes can be
turned on in case of injury.
________
Cells near injury are
stimulated to divide
to heal and replace
damaged/missing cells
and shut off when the
repair has been made.
CELL CYCLE REGULATORS
Levels of this protein rose and fell with
the cell cycle so it was named
__________
CYCLIN because it seemed to
control the cell cycle.
A whole family of
CYCLINS have since been
discovered that regulate the
TIMING of CELL CYCLE
_____________________
in EUKARYOTIC CELLS
Pearson Education Inc; Publishing as Pearson Prentice Hall
OTHER REGULATORS
INTERNAL
______________
REGULATORS
Proteins that respond to events inside
the cell.
Allow cell cycle to proceed only if
certain processes have happened
EX: Cell can’t enter mitosis until all the
chromosomes have been copied
OTHER REGULATORS
EXTERNAL
______________
REGULATORS
Proteins that respond to events outside
the cell.
Signals tell cell to speed up or slow
down the cell cycle
EX:
Growth factors stimulate cells to divide
Especially important during
wound healing and
embryo development
http://www.suite101.com/files/topics/6234/files/tail_HumanTail.gif
EXTERNAL REGULATORS
Molecules on the surface of neighboring
cells act as signals to slow down
or stop the
cell’s cycle.
These signals prevent
excessive growth and
keep tissues from
disrupting each other.
Pearson Education Inc; Publishing as Pearson Prentice Hall
Cancer cells have lost control
of their cell division genes
SEM Image by: Riedell
CHO (Chinese Hamster Ovary) cells in culture
NO CONTACT INHIBITION
Cancer cells don’t stop
when they touch nearby
cells. . .
they just keep growing!
See a video
That’s what makes
a tumor.
http://www.exn.ca/news/images/2000/08/02/20000802-cancer.jpg
Cancer cells
• Don’t stop dividing
• Like a “car with no brakes”
• Can spread to new places
(METASTASIS)
• ______________
Carcinogens are substances that
can damage DNA and cause cancer
Ex: Cigarette smoke (OR CHEW),
Radiation, chemicals in environment,
even viruses,
http://www.dfci.harvard.edu/abo/news/publications/pop/fall-winter-2004/images/metastasis_1.jpg
Cancer cells
Cancer is complicated and can have many
causes, but all cancers have one thing in
common . . .…
They have lost control over their
_____________.
CELL CYCLE
Many cancers cells have a damaged or defective
gene called p53
_____, so they can’t respond to
normal cell signals to control their growth.