Mitosis- Chapter 6
Sections 1-3
Objectives
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Identify four examples of cell division in eukaryotes and one
example in prokaryotes.
Differentiate between a gene, a DNA molecule, a
chromosome, and a chromatid.
Compare haploid and diploid cells.
Differentiate between homologous chromosomes,
autosomes, and sex chromosomes.
Predict how changes in chromosome number or structure
can affect development.
Why do cells divide?
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Repair
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Growth & development
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Make gametes (sex-cells; sperm or
egg)
Asexual Reproduction
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Reproduction by
– Binary Fission
– Fragmentation
– Vegetative Propagation
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Genetically identical offspring
Don’t need partner to reproduce
Binary Fission
Fragmentation
Sexual Reproduction
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Reproduction requires gametes
Genetically different offspring
Sexual ReproductionSimple version
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Daddy’s sperm meet Mommy’s egg
This sperm “eats” a hole for itself into
the egg to get its DNA in
This fertilized cell is called a zygote
This zygote divides and grows into a
baby by Mitosis
Prokaryotes vs
Eukaryotes
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Prokaryotes use asexual reproduction
Eukaryotes may use asexual OR sexual
reproduction
Prokaryotes reproduce more quickly
Eukaryotes reproduce more slowly
Prokaryotes vs
Eukaryotes
Focus on Eukaryotes (us)
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Gene- part of DNA
that codes for
particular trait
Chromosomemade of coiled DNA
and protein
More Important Terms
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Centromere- center
point where two
chromatids are
attached
Chromatid- half of a
chromosome
Chromosome
Eukaryote Cell Division
http://www.cellsalive.com/cell_cycle.htm
Cell Cycle
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S phase
(DNA synthesis;
chromosome duplication)
Consists of
– Interphase
– Mitosis
Interphase
(90% of time)
G2
G1
Mitotic
phase (M)
(10% of time)
Cytokinesis
Mitosis
Interphase
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Cell spends 90% of its time here
G1- 1st growth phase
S- synthesis of DNA
G2- 2nd growth phase
There are checkpoints throughout the
cell cycle
Mitosis- (growth/repair)
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Begins with 1 diploid cell, ends with 2
diploid cells
Diploid = twice the number of
chromosomes (2N)
One chromosome set comes from
mom, the other from dad
All of our body cells are diploid (except
for sperm and egg)
Remember: produces 2 genetically identical cells!
Basic Steps of Mitosis:
“PMAT”
 P- Prophase
 M- Metaphase
 A- Anaphase
 T- Telophase
Prophase
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Nuclear membrane
dissolves
Chromosomes
become visible
Metaphase
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Chromosomes align
on the equator
Spindle fibers form
and attach to
centromere
Anaphase
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Centromeres break
Chromatids move
toward the poles as
spindle fibers shorten
Telophase
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Nuclear envelope
forms
– Cleavage furrow in
animals
– Cell plate in plants
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Daughter cells form
when Cytokinesis
(cell splits into two)
occurs
Cleavage Furrow
Cell Plate
When Mitosis goes bad
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Cell Cycle checkpoints don’t work
properly
Cell can divide when it shouldn’t
Cell can mutate
A benign (harmless) tumor can form
Cancer may develop
Cell Cycle CheckPoints
What is Cancer?
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Named for organ or tissue where its found
Cells that divide out of control due to a
mutation in the DNA
These “out of control” cells can
destroy/invade normal cells and tissues
Cancer can spread from a malignant
(harmful) tumor
Metastasis is cancer cells that have spread
Figure 12-17x1 Breast cancer cell
Lymph
vessels
Tumor
Glandular
tissue
Metastasis
A tumor grows from a
single cancer cell.
Cancer cells invade
neighboring tissue.
Cancer cells spread through lymph
and blood vessels to other parts of t
body
Figure
Common Types of Cancer
Cancer Treatment
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Radiation can be used for skin cancer
Chemotherapy involves drugs that
stop Mitosis throughout the body
– Chemotherapy drugs not only try to kill
cancer cells but it makes wounds slower
to heal, hair to be lost, immune system to
be weakened
Cancer “Caution” Signs
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Change in potty habits
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A sore that does not heal
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Unusual bleeding or discharge
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Thickening of tissue or new lump
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Indigestion
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Obvious changes to moles or warts
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Nagging cough that lasts for a month or more
Cancer Preventionwhat YOU can do
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Not smoking
Limiting time in the sun
Eating high-fiber, low-fat diet
Visit Doctor regularly
Perform regular self-examinations