Download Cell Growth and Division

10/3 Bell Work
How far can a dog run into the woods before he’s
running out?
10/3 Schedule
Finish test?
Notes Ch 10.1 “Cell Reproduction in “Cell Growth
and Division” unit online
Directed Reading Ch 10
Quarter end THURSDAY! TED Talks
or Scientist EC must be in.
Assignments:
UNIT : Cell Growth &
Division
Ch 10 Objectives
1. Describe the purposes and processes of cell reproduction.
“The cell never acts; it reacts. “ Ernst Haeckel 1866
Ch 10.1 “Cell Reproduction”
Objectives
1. Explain why cells divide.
2. Describe how DNA is packaged and stored.
3. Describe how cells prepare for division.
Cell Division… Er
Multiplication Intro
Each time a cell reproduces, it divides into two new cells.
Each of these new cells divide to make four new cells.
If this continues, how many cells are there after the 6th
division?
Division
# Cells
1
2
2
4
3
8
4
16
5
32
6
64
Reproduction’s Purpose
Multicellular organisms usually grow by
making new cells, not bigger ones.
New cells are needed to help tissues and
organs grow.
Old cells die and new take their place.
New cells also replace damaged cells.
Reproduction’s Purpose
Some organisms can replace missing parts.
New cells replace damaged areas.
Many plants and some animals
Reproduction Purpose
Cell Size
A cell grows by building more cell products. They take
in more nutrients, process them, and get rid of wastes.
Size is limited by surface area–to-volume ratio. Things
must travel farther to reach where they are needed.
Reproduction’s Purpose
Cell Maintenance
Cell size is also limited by DNA.
DNA instructions cannot be copied quickly enough to
make the proteins that the cell needs to support itself.
No protein microtubules, no cytoskeleton.
No cytoskeleton = less support and movement.
Reproduction’s Purpose
Making New Cells
Each “daughter” cell has a higher surface area–tovolume ratio than its parent does.
New cells are smaller and easier to maintain.
Each new cell also gets an entire copy of DNA.
Chromosomes
Each cell has a large amount of DNA that must be
condensed into a very small volume.
DNA is packaged into chromosomes.
The DNA is organized into units called genes.
They code for RNA and then proteins.
Proteins determine many characteristics
Hair texture and color
Skin color
Bone strength…
Chromosomes
Prokaryotic Chromosomes
Bacteria have a single circular molecule
of DNA that contains thousands of
genes.
They condense by repeated twisting
upon itself.
Some bacteria also have
“extra” plasmid DNA.
Chromosomes, continued
Eukaryotic Chromosomes
Eukaryotic cells have many more genes arranged on
several linear DNA molecules.
This DNA condenses into chromosome structures with
the help of many proteins.
The DNA and proteins are called chromatin.
Chromosomes, continued
Eukaryotic Chromosomes
The first level of packaging is done by protein histones.
Eight histones form a disc-shaped histone core.
Chromosomes, continued
Eukaryotic Chromosomes
DNA wound around a series of histone cores in a
regular manner is called a nucleosome.
The string of nucleosomes line up in a spiral to form a
cord that is 30 nm in diameter.
Nucleosome cord
Chromosomes, continued
Eukaryotic Chromosomes
During most of a cell’s life, chromosomes exist as
nucleosomes.
As the cell prepares to divide, the chromosomes
condense to ensure the DNA does not tangle during
cell division.
Stop Notes
Whitefish, Onion, or Ascaris
Cells
Answer in your notebook.
1.
Make a representative drawing of the cells on med/high
power.
2.
Look at the nuclei. Categorize (group) them by the way they
look. Draw one from each group.
3.
Describe the differences you saw in nuclei size/shape/etc.
Chromosomes, continued
Eukaryotic Chromosomes
The nucleosome cord forms loops that attach to a
protein scaffold. Then they coil into the final, most
highly condensed chromosome.
Chromosomes, continued
Eukaryotic Chromosomes
Each of the two thick strands of a fully
condensed, duplicated chromosome are
called a chromatid.
Each chromatid is a single, long molecule of
DNA.
Chromosomes, continued
Eukaryotic Chromosomes
Sister chromatids are held together at a region called the
centromere.
During cell division, the sister chromatids separate, and one
ends up in each daughter cell.
Each new cell has the same genetic information as the
parent.
Preparing for Cell Division
All new cells are produced by dividing other cells.
All cell structures and DNA have to double.
Cell membrane
Ribosomes
Organelles for eukaryotes
Preparing for Cell Division
Prokaryotes (Bacteria)
The circular DNA copies attach to the cell
membrane.
The membrane pinches in, separating the
DNA loops while the cell almost doubles
in size.
Bacteria Division =
Binary Fission
Preparing for Cell Division,
continued
Eukaryotes
Reproduction is more complex than in bacteria.
1. Organelles need to be copied.
2. DNA strands must be copied, sorted, and separated.
Division, it’s all in the
chromosomes…
Watch the video clip.
1. Are they talking about prokaryotic or
eukaryotic chromosomes? How do you
know?
2. How many phases are there in mitosis?
Name them.
3. According to the video, what are
chromosomes made of?
Chromosome (telephone parody).flv
To Clone or Not to Clone?
Day 1/2
Download and read “To Clone or Not to Clone?” from
“Case Studies and Projects.”
Use links/sites on p. 3 to start exploring mitosis,
meiosis, cloning, and the ethical issues involved.
Answer Learning Questions #1-7
Back of Write-Up sheet or lined paper
In your own words!
Cite your sources!
10/13 Bell Work
Even if they are starving, natives living in the Artic don’t
harvest penguin eggs. Why not?
Penguin Distribution
10/13 Schedule
To Clone or Not to Clone?
Assignments:
To Clone or Not to Clone?
Day 2/2 for research
Use links/sites on p. 3 to explore mitosis, meiosis,
cloning, and the ethical issues involved.
Answer Learning Questions #1-7
Back of Write-Up sheet or lined paper
In your own words!
Cite your sources!
Start on Write-Up essay if finished.
10/14 Bell Work
In an ordinary deck of playing cards, two Jacks have two
eyes and two Jacks have one eye.
How many eyes are on the four Jack cards?
10/14 Schedule
Notes Ch 10.2 “Mitosis”
To Clone or Not to Clone?
7 Learning Questions
Write Up
Ch 10 “Cell Reproduction” test MONDAY
Assignments:
1. To Clone? Wrtie up & Learning Quest due FRIDAY
Division Intro
How are the players, the midfield line, and the goal posts
similar to the structures of a cell involved in mitosis and
cell division?
Ch 10.2 “Mitosis”
Objectives
Analyze the cell cycle.
Describe and identify the 4 stages of mitosis
Explain cytokinesis.
Eukaryotic Cell Cycle
The cell cycle is a repeating cycle of growth and
division.
There are five stages. The first three are interphase.
The other two are cell division.
Eukaryotic Cell Cycle,
continued
Interphase – Growing & Getting Ready
Amount of time depends on cell type.
Skin, hair, and stomach cells divide often. They spend little
time in interphase.
Nerve cells divide very rarely and are almost always in
interphase.
Skin cells divide about
every 50-100 days
Nerve cells develop when you
are born, and can live as long as
you do…
Eukaryotic Cell Cycle
Interphase
First gap phase (G1) = A cell grows rapidly as more
organelles are built.
Synthesis phase (S) = DNA is copied.
Second gap phase (G2) = The cell continues to grow.
Microtubules are organized in the cytoplasm.
Eukaryotic Cell Cycle,
continued
Cell Division
Mitosis divides the nucleus into 2 daughter nuclei.
Cytokinesis separates the organelles and the cytoplasm.
Stages of Mitosis
Although mitosis is a continuous process, biologists
traditionally divide it into four stages.
The stages are… PMAT
1. prophase
2. metaphase
3. anaphase
4. telophase
Stages of Mitosis, continued
Stage 1 Prophase
Chromosomes begin to condense and become visible
under a microscope.
Stages of Mitosis, continued
Stage 1 Prophase
The nuclear membrane breaks down. The centrosome
assembles the spindle at opposite sides of the cell.
Each spindle fiber is a microtubule. They run at a
right angle to the cell’s equator.
Spindle and fibers in green
Stages of Mitosis, continued
Stage 2 Metaphase
Chromosomes move to the center of the cell and line
up along the equator.
Spindle fibers link the poles and the centromere of
each chromosome.
Metaphase
Stages of Mitosis, continued
Stage 3 Anaphase
Once all of the chromosomes are lined up, the spindle
fibers shorten by shortening the microtubules.
Sister chromatids move toward opposite poles.
Anaphase
Stages of Mitosis, continued
Stage 4 Telophase
A nuclear envelope forms around the chromosomes at
each pole of the cell.
Chromosomes uncoil back to their original chromatin
form.
The spindle dissolves and spindle fibers break down.
Telophase
Clone Write-Up
Write an essay to answer the following questions using evidence
from your research.
Describe what happened to Ted and his wife and the
decision they have to make. (Reading)
Describe the process that could be used to clone humans
and some of the possible problems. (7 Questions)
Persuade Ted and his wife to clone/not to clone. Explain.
(7 Questions)
Due FRIDAY!
10/15 Bell Work
Karry Queen, famous American novelist, was found slumped at a
desk next to an empty bottle of sleeping pills. His last conversation
was with the bellhop about how excited he was to be visiting
England for the first time. The detective read the note and declared
it a murder!
Note: I have lost my will to live. My writing was the centre of my life, but
now I realize they were just trashy novels. As the colour fades from my eyes, I
can only hope for a better life in the next world.
Why was the detective so sure the author was murdered?
10/15 Schedule
Notes Ch 10.2 and 10.3 “Regulation”
Work time
Mitosis Worksheet
To Clone or Not to Clone?
7 Learning Questions
Write Up
Ch 10 “Cell Reproduction” test MONDAY
Assignments:
1. To Clone? Wrtie up & Learning Quest due FRIDAY
2. Mitosis Worksheet due MONDAY
Cytokinesis
As mitosis ends, cytokinesis begins. The cytoplasm is separated,
and two cells are formed.
Each daughter cell has about half of the parent’s cytoplasm and
organelles.
The end result of mitosis and cytokinesis is two genetically identical
cells.
Cytokinesis, continued
Separating the Cytoplasm
In animal cells and other cells that lack cell walls, the
cell membrane is pinched in half by a belt of protein
threads.
In plant cells and other cells that have rigid cell walls,
the cytoplasm is divided in a different way.
Cytokinesis, continued
Separating the Cytoplasm in Plants
Vesicles line up across the middle of the cell.
These vesicles fuse to form a membrane-bound cell wall
called the cell plate.
Eventually the cell plate separates the plant cell into
two new plant cells.
Ch 10.3 “Regulation”
Objectives
Describe factors that control cell growth and division
Explain how feedback signals affect the cell cycle.
Explain how cell cycle issues lead to cancer.
Mitosis Graph Check
One cell divides into two daughter cells. Each of those
daughter cells divide into two more daughter cells. Make a
graph that shows how the number of cells increases.
Division
# Cells
1
2
2
4
3
8
4
16
5
32
6
64
7
128
Controls
Division is highly controlled.
Depends on protein and
environmental signals.
Other cells and organs give signals.
Water and nutrients control
growth.
Cell cycle phases are controlled by
proteins.
Different signals determine
what stem cells become…
Checkpoints
During the cell cycle, cells check to make sure they are
ready for the next phase.
Feedback signals delay or trigger the next phase.
Three major checkpoints
G1 Checkpoint
G2 checkpoint
mitosis checkpoint
Checkpoints
Checkpoints, continued
G1 Checkpoint
Before DNA is copied, the cell checks its surroundings.
Favorable conditions + cell healthy and large enough = cell
enters the synthesis phase.
Unfavorable conditions = resting phase
Muscle and nerve cells often stop
here.
Checkpoints, continued
G2 Checkpoint
Cell checks for DNA mistakes so they can be corrected
by enzymes.
Proteins double-check the cell is large enough.
If the cell passes the G2 checkpoint, then the cell may
begin to divide.
Checkpoints, continued
Mitosis Checkpoint
The cell checks that the chromosomes are properly
attached to the spindle fibers during metaphase.
Reasons for Checkpoint
Sister chromatids may not separate properly.
Ensures the DNA is split equally.
Cancer
Each year, more than 1 million Americans are diagnosed
with cancer.
Cancer is a group of diseases caused by uncontrolled
cell growth. Tumors invade and destroy healthy tissues
Mouth cancer
Leukemia, cancer of
white blood cells.
Cancer, continued
Loss of Control
Damaged DNA causes the cell to respond improperly
to cell cycle controls.
DNA problem = faulty instructions = protein problem
Protein problem could effect division, checkpoints, or signals
Facial
tumors
Cancer, continued
Development – Kinds of Tumors
A benign tumor does not spread to other parts of the
body and can often be removed by surgery.
Hemangiomas: benign tumor or
birthmark caused by abnormal
number of blood vessels in skin.
Cancer, continued
Development – Kinds of Tumors
A malignant tumor invades and destroys nearby healthy
tissues and organs.
Malignant cells can break loose and grow throughout
the body (metastasis). Then it’s very difficult to treat.
Tasmanian devil facial tumor.
10/16 Bell Work
The “Soul-Ace Hotel” was holding its first birthday party
and all eight of the regular customers were invited. The
owner ordered the cake and cut it into 4 slices since she
only expected half of the people to attend. To her dismay,
everyone invited showed up.
How can she make the cake into eight equal size pieces
with just one cut?
10/16 Schedule
Finish notes 10.3 “Regulation”
Tasmanian Devil Video
Review Mitosis
Work time
Mitosis Worksheet
To Clone or Not to Clone?
7 Learning Questions
Write Up
Ch 10 “Cell Reproduction” test MONDAY
Assignments:
1. To Clone? Wrtie up & Learning Quest due TODAY
2. Mitosis Worksheet due MONDAY
Cancer, continued
3 Basic Treatments
Drugs: Chemical or “chemo”therapy can treat some cancers.
Surgery to remove affected organ
Radiation: High-energy rays destroy cancer cells
Cancer Drugs
Side effects...
- Hair loss
-- Anemia
- Nausea
- Low white blood cell count
Think about the cells that are in these effected areas.
What do they have in common?
What do these cells have in common with cancer and
why are they effected by these drugs?
EarthSky snippet
Cancer, continued
Prevention – Avoid the triggers
Ultraviolet radiation in sunlight can damage genes that
control the cell cycle.
Cancer, continued
Prevention – Avoid the triggers
Chemicals in cigarette smoke and chewing tobacco also
affect how cell growth and division is regulated.
Tasmanian Devils
1. Why is this cancer unusual?
2. How has the Devils’ behavior lead to the spread of this
cancer?
3. Why is this cancer such a concern for scientists?
4. Could infectious cancer happen in humans? How?
Taz Cancer Video
Review Mitosis
Do the following happen in interphase or mitosis?
Cell growth occurs.
Nucleus is divided.
Production of proteins is high
DNA is synthesized.
Identify the mitosis stages.
nd
2
Quarter!
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Quarter!
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7
Hr
Please find your new seat.
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10/19 Bell Work
What is the product of the following series?
(X-A) x (X-B) x (X-C) …. (X-X) x (X-Y) x (X-Z)
10/19 Schedule
7 minutes to study and ask specific questions on
material
Growth and Division Test
Use paper notes
Electronics are music ONLY. Leave them sitting on
your desk.
Finish missing assignments
Assignments:
1. To Clone? Wrtie up & Learning Quest LATE
2. Mitosis Worksheet due TODAY