Cell Reproduction
Chromosomes
Mitosis
Meiosis
March 29th Part I
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Return Papers
Notes on Chromosomes, Mitosis
Cell Reproduction Handout
Video: Cell Cycle, Mitosis
Break
Lab 11: Exercises I, III
• Modeling Mitosis with Playdough
• Mitosis in Whitefish Blastula
• Break
Chromosomes
Cell Division
• Cell Division is the process by which
cells reproduce.
• information in the cell is contained in
genes → genes code for proteins →
proteins carry out cellular functions
• Each body cell that results from cell
division must have an exact copy of
the DNA in the original cell.
Chromosome Structure
Chromosome
Structure
Chromosome Structure
Chromosome
Structure
Chromosome Number
Karyotype
Diploid vs. Haploid
• Diploid (2n): a cell that
contains both chromosomes
of a homologous pair
• Humans = 46 (somatic cells:
body cells)
• Haploid (n): a cell that has
only one chromosome of
each homologous pair
• Humans = 23 (gametes:
egg and sperm)
Mitosis
Mitosis
• Mitosis: the division of the cell
nucleus in which the chromosomes
in the parent cell divide into two
identical sets
• In somatic cells (body cells), the
number of cells is increased
without changing the information
contained in the DNA or the
amount of DNA in those cells.
Binary Fission
• Binary Fission: cellular division of
unicellular organisms that produces
identical offspring
Cell Cycle
Overview
Control of Cell Size
• Cell Size
(SA/V)
• Regulatory
Checkpoints
- Enzymes
Important Structures
Equator
Polar
Fibers
Asters
Kinetechore
Centrioles
Kinetechore
Fibers
Mitosis in Plants
Cleavage Furrow & Cell Plate
Lab 11: Mitosis and Meiosis
• Modeling Mitosis
• Mitosis in Whitefish Blastula Cells
Lab 11 Objectives
• Understand, identify stages of mitosis
and meiosis
• Understand the difference between
mitosis and meiosis
• Identify different stages of mitosis in
whitefish blastula cells
March 29th Part II
• Notes on Meiosis
• Videos: How Meiosis Works; Stages of
Meiosis
• Lab 11: Exercise II
• Modeling Meiosis with Playdoh
• Meiosis Reinforcement Worksheet
• Break
Meiosis
Overview
Genetic Recombination
• Genetic Recombination: the process
that results in chromosomes being
arranged in many different ways
• crossing-over between homologues or
chromatids
• homologous pairs separate
independently in meiosis I
• sister chromatids separate
independently in meiosis II
CROSSING
V
E
R
CROSSING
V
E
R
Independent
Assortment
Lab 11: Mitosis and Meiosis
• Modeling Meiosis
March 29th Part III
• Notes- Cancer: Uncontrolled Cell
Growth
• Video: How Cancer Spreads
• Video: Cancer Cells
• Lunch
• Video: Cancer Warrier
• Review Questions: Mitosis, Meiosis
• Review for Exam II
Notes: The Cell Cycle and
Cancer
What is Cancer?

Simplest definition
From the American Cancer Society
“ cancer is a group of diseases characterized by
uncontrolled growth and spread of abnormal
cells. If the spread is not controlled, it can result
in death.”

Tumor
– Two types:
 Benign (non-cancerous) – this is not cancer!
– Does not spread; it can eventually become malignant
in some cases.

Malignant (cancerous) – this is cancer!
– Has the potential to spread to other parts of body.
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Cancer is a disease of the cell cycle.
Some of the body’s cells divide
uncontrollably and tumors form.
Tumors in Liver
Tumor in Colon
Cancer: Unregulated Cell Division
Quick Write !
 Have you ever wondered how cancer
grows? Take a close look at the cancer
cell division in this realistic 3D
animation. Compare and contrast
healthy animal cell division to
unregulated cancer cell division
 What would it feel like to be the nucleus
of a cell that has been taken over by
cancer ?

DNA mutations disrupt the cell cycle.
Mutations may be
caused by:
1. Radiation
2. Smoking
3. Pollutants
4. Chemicals
5. Viruses
While normal cells will stop dividing if there is a
mutation in the DNA, cancer cells will continue to
divide with mutation.
Due to DNA mutations, cancer cells
ignore the chemical signals that start and
stop the cell cycle.
Role of Cell Division in Cancer
Top = normal cell division
Bottom = unregulated cell
division and tumor formation
Malignant
If tumor invades
surrounding tissue
(cancerous)
Benign
If tumor has no effect on
surrounding tissue
(non-cancerous)
Metastatic
If individual cells break
away and start a new
tumor elsewhere
(cancerous)
Image from the National Cancer Institute48
Review: The cell cycle has four
phases and controls cell division

Two gap or
growth
phases (G1
and G2)
 S phase DNA
synthesis
 M phase Mitosis
Interphase
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Cell Cycle Checkpoints

Three checkpoints in cell cycle
– G1-S transition
– G2-M transition
– Exit M phase transition

Checkpoints are where the cell
assesses whether conditions
are favorable for cell division.
When the environment is not
favorable (for example, when
the cell’s DNA is damaged), a
protein called p53 can stop the
cell cycle and cause the cell to
die.
When the proteins that regulate
the cell cycle are mutated or
absent, cells can divide
uncontrollably, leading to
cancer.


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Due to DNA mutations, cancer cells cannot
communicate with neighboring cells. Cells
continue to grow and form tumors.
Skin cancer
(cancer cells dividing: click on
picture.)
Treating Cancers
Cancer treatments include drugs that can stop
cancer cells from dividing.
Ed Ted Video: Cancer Cell
Behavior
1.
2.
How many cells are in the human
body ?
Cancer cells are rogue clones. List
and describe three mutations that
allow these cells to escape the
normal restrictions placed on our
body’s cells.
Ed Ted Video: Cancer Cell
Behavior
3.
Why doesn't cancer just die off after
one rogue division?
Most of the time, a cell detects a glitch and
shuts itself down, or the system detects a
troublemaker and eliminates it, but
sometimes enough mutations pass the
failsafes, and cancer cells divide recklessly
Ed Ted Video: Cancer Cell
Behavior
4.
There are many actions that you can
take to improve your lifestyle and
reduce your risk of developing
cancer. How can you take an active
role in cancer prevention?
Ed Ted Video: Cancer Cell
Behavior
5.
a.
b.
c.
d.
Which is not a routine treatment
recommended to cancer
treatments?
Radiation
Local anesthetics
Chemotherapy
Surgery
Ed Ted Video: Cancer Cell
Behavior
6.
Harry is diagnosed with prostate
cancer. What are some questions
that he should ask his doctor? Why
should he ask those questions?
Ed Ted Video: Cancer Cell
Behavior
7.
a.
b.
c.
d.
Why are chemotherapy and radiation
dangerous?
Neither radiation nor chemotherapeutic
drugs target only cancer cells
Radiation hits whatever you point it at
The bloodstream carries
chemotherapeutics all over the body
All of the above
Ed Ted Video: Cancer Cell
Behavior
8.
Why are chemotherapeutic drugs
generally successful against cancer
cells?