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Genes, Mitosis and Cytokinesis
12/17/14
Mitosis
!
CELL DIVISION!
ü Mitotic division results
in genetically identical
eukaryotic cells or a"
clone "
_____
ü Mitosis is the basis of "
________
asexual! reproduction
G. Podgorski, Biol. 1010
"
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Genes, Mitosis and Cytokinesis
12/17/14
LIFESPAN OF SOME CELLS IN THE HUMAN BODY!
"
Prokaryotes!
ü  Granulocytes: eosinophils basophils, neutrophils "
ü  Stomach lining cells "
ü  Colon cells "
"
ü  Epithelia of small intestine
less"
ü  Platelets
"
"
ü  Skin epidermal cells "
ü  Lymphocytes"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
"
ü  Red blood cells
(120 days)"
ü  Pancreas cells
more
ü  Brain cells "
"
"
"
"
"10 hours to 3
days"
"2-3 days"
"3-4 days"
"1 week or
"10 days"
"2 - 4 weeks"
"2 months - a
year "
"4 months
"
ü Prokaryotes
simply divide
their cells in
two by binary
fission "
1 year or
"
"
"
"
http://instruct1.cit.cornell.edu/
"95-100 years"
Eukaryotes!
ü Eukaryotes must divide their nucleus"
ü When nucleus divides, the DNA"
____ duplicates.
This is called replication."
Organelles" must also replicate"
ü  __________
Why do cells divide?"
ü Reason #1:"
ü If a cell kept getting bigger,
there wouldn’t be enough
DNA to provide sufficient
information"
"
Why do cells divide?"
Why do cells divide?"
ü Reason #2:"
ü Reason #3"
ü If a cell kept getting
bigger, couldn’t move
nutrients and wastes
across the cell
membrane"
G. Podgorski, Biol. 1010
ü To replace old and worn out cells."
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Genes, Mitosis and Cytokinesis
The three main
components of
the cell cycle.
12/17/14
After DNA is replicated it
must be packaged into chromosomes.
Why?
Interphase
duplicated
chromosome
What’s so important about
cell division?
chromatin
DUPLICATING CHROMSOMES
If there are 6
sister chromatids,
how many
chromosomes are
in the cell?
DNA is Condensed into Visible Chromosomes Only For Brief
Periods in the Life of a Cell
centromere
95% of the time, chromosomes are
like this.
Easily visible chromosomes are
apparent perhaps 5% of the time in
an actively growing cell and less in a
non-growing cell.
A Karyotype is an Arranged Picture of Chromosomes At Their Most
Condensed State
Note that almost all chromosomes come in homologous pairs.
Boy or
girl?
A normal
human
karyotype
G. Podgorski, Biol. 1010
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Genes, Mitosis and Cytokinesis
12/17/14
The Cell Cycle-notes"
ü Series of 3 main events that cells go
through as they grow and divide."
1. INTERPHASE
a. G1- growth phase; organelles
replicated.
b. S- chromosomes are replicated
c. G2- growth; double check
before division.
2, MITOSIS (PMAT)
3. CYTOKINESIS
I Punched Melanie And The Cat
ü  1.Prophase"
ü  2.Metaphase"
ü  3.Anaphase"
MITOSIS highlights"
- Mitosis Divides the Duplicated Chromosomes: THE DANCE
OF THE CHROMOSOMES!
1. Prophase:
• chromatin condenses
• centrioles separate
• spindle begins to form
• nuclear envelope breaks down
2.Metaphase:
• Lasts only a few minutes
• Chromosomes line up on the
metaphase plate (middle)
• Spindle fibers connect to the
centromere of each chromosome
3.Anaphase:
• Centromeres separate
• Chromosomes move to
opposite sides of the cell.
4.Telophase:
• Chromosomes uncoil
• Nuclear envelope reappears
• Spindle begins to break apart
• Nucleolus becomes visible
Mitosis Precisely and Evenly Divides Duplicated Chromosomes
anaphase
centromere
interphase
prophase
metaphase
What is a centromere?
G. Podgorski, Biol. 1010
ü  4.Telophase"
telophase
Two New Identical Daughter Cells!
Cytokinesis is NOT included in mitosis.
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Genes, Mitosis and Cytokinesis
12/17/14
Mitosis in Action
Cytokinesis"
ü Division of
cytoplasm"
ü Occurs differently in
plants than in
animals"
Blue
shows
DNA,
green
shows
spindle
fibers.
Cytokinesis in plant cells:
Cytokinesis in
animal cells:
In animal cells, a
cleavage furrow
forms and
separates
daughter cells.
In plant cells, a cell plate forms and
separates the daughter cells.
Cleave furrow in a dividing frog cell.
Onion Root Tip
CANCER
Cancer develops when cells in a part of the
body begin to grow out of control.
Brain cancer cell
G. Podgorski, Biol. 1010
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Genes, Mitosis and Cytokinesis
12/17/14
Cancer Is One Outcome of A Runaway Cell Cycle
What’s in a name?"
Carcinoma—any tissue "
communicating with the outside"
Sarcoma—supporting "
tissue"
Lymphoma—immune "
system"
Leukemia—blood"
The good and the bad"
Benign —locally grown; tumor remains"
in the original site of growth"
Malignant a.k.a. “The bad”—ability to "
spread"
ü STOP!"
Metastasize—when a tumor has spread from "
its original growth site"
Cell division is a fundamental process!
ü  All cells come from pre-existing cells"
ü  It is necessary to replace worn out cells in
multicellular organisms"
ü  It is required for growth in multicellular
organisms"
ü  It is necessary for reproduction in unicellular or
multicellular organisms "
G. Podgorski, Biol. 1010
Cell Cycle"
ü Series of events that
cells go through as
they grow and divide"
ü Cell grows"
ü Prepares for division"
ü Divides to form
daughter cells"
ü Daughter cells restart
the cycle"
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Genes, Mitosis and Cytokinesis
12/17/14
Proteins and Their
Production – The
Primary Reason for
DNA
DNA and Its Faithful Replication –
Because DNA stores genetic
information and is faithfully
replicated, information is passed
largely unaltered from cell-to-cell,
generation-to- generation.
Cell division requires coordinated division of chromosomes
(mitosis) …..
DNA Replication –
Simple in Principle,
Complicated in Practice
…… and division of the
cytoplasm (cytokinesis).
The Link Between DNA Replication and Chromosome Duplication
QuickTime™ and a
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are needed to see this picture.
G. Podgorski, Biol. 1010
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Genes, Mitosis and Cytokinesis
QuickTime™ and a
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QuickTime™ and a
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are needed to see this picture.
G. Podgorski, Biol. 1010
12/17/14
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
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