Transcript Animal Mitosis - New Braunfels ISD

Lesson Objectives
 Contrast cell division in prokaryotes and
eukaryotes.
 Identify the phases of the eukaryotic cell
cycle.
 Explain how the cell cycle is controlled.
 Define cancer, and relate it to the cell
cycle.
 Describe chromosomes and their role
in mitosis.
 Outline the phases of mitosis.
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binary fission
cancer
cell cycle
cell division
cytokinesis
DNA replication
interphase
mitosis
Tumor
somatic
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anaphase
centromere
chromatid
chromatin
chromosome
gene
homologous
chromosomes
metaphase
prophase
telophase
 How
does it differ between
eukaryotes and prokaryotes?
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Most prokaryotic cells divide by the
process of binary fission.
Blue and red lines indicate old and newlygenerated bacterial cell walls, respectively.
Eventually the parent cell will pinch apart to form
two identical daughter cells.
Step 1: DNA Replication. Just
before the cell divides, its DNA is
copied. This results in two identical
chromosomes instead of just one.
This step is necessary so that when
the cell divides, each daughter cell
will have its own chromosome.
 Step 2: Chromosome
Segregation. The two
chromosomes segregate, or
separate, and move to opposite
ends (known as poles) of the cell.
 Step 3: Cytokinesis. A new
plasma membrane starts growing
into the center of the cell, and the
cytoplasm splits apart, forming two
daughter cells. The two daughter
cells that result are genetically
identical to each other and to the
parent cell.
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How do little elephants grow up to be
BIG elephants?
MITOSIS
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To create two identical daughter cells
that are genetically identical to the
parent cell
Asexual Reproduction
Mitosis
Mitosis is the process in which
the nucleus divides to form two
new nuclei. How does mitosis
differ in plants and animals?
Somatic cells
 (all body cells except gamete (sex)
cells)
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The process of asexual
reproduction begins after
a sperm fertilizes an egg.
It starts with a zygote
Skin cancer - the abnormal growth of
skin cells - most often develops on skin
exposed to the sun.
Cell that reproduce by asexual
reproduction reproduce constantly.
Animated Cell Cycle
http://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
& Cytokinesis
Mitosis
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Growth Phase 1/G1 phase- (cell growth) Cell increases in
size and makes more proteins and organelles
Synthesis Phase/S phase- (DNA Replication) number
doubles
Growth Phase 2/G2 phase- (preparing for cell division)
organelles need for cell division
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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Genetic material inside the nucleus begins to condense and
the duplicated chromosomes are visible in the form of
chromatids.
Spindle fibers begin to form outside the nucleus between
centrioles which move to opposite ends of the cell
At the end of prophase, the nucleolous and nuclear
membrane disappear
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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Chromatids (or pairs of chromosomes) attach
to the spindle fibers at the centromeres and
line up in the middle of the cell.
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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Chromatids separate and begin to move to
opposite ends of the cell as individual
chromosomes when spindle fibers shorten.
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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Chromosomes begin to uncoil and form chromatin
Nuclear envelope reforms around each group of
chromatin
Spindle fibers begin to break apart
Animal Cell begins to “pinch” called a cleavage furrow
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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Division of the cytoplasm
In animal cells the cell membrane moves inward creating a
clevage furrow, pinching all the way through, creating two
daughter cells – each with its own nucleus with identical genetic
code.
In plant cells, a cell plate forms along the equator of the parent
cell. Then, a new plasma membrane and cell wall form along each
side of the cell plate.
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If the cell cycle occurred without
regulation, cells might go from
one phase to the next before
they were ready.
 What controls the cell cycle? How
does the cell know when to grow,
synthesize DNA, and divide?
 The cell cycle is controlled mainly
by regulatory proteins, cyclin.
These proteins control the cycle
by signaling the cell to either
start or delay the next phase of
the cycle. They ensure that the
cell completes the previous
phase before moving on.
Regulatory proteins control the
cell cycle at key checkpoints,
which are shown in Figure to
the right. There are a number of
main checkpoints.
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Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
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- Cell Division
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http://www.cellsalive.com/mitosis.htm
Cancer is a disease that occurs when the cell cycle is no longer regulated.
This may happen because a cell’s DNA becomes damaged.
Damage can occur due to exposure to hazards such as radiation or toxic
chemicals. Cancerous cells generally divide much faster than normal cells.
They may form a mass of abnormal cells called a tumor (see Figure below).
The rapidly dividing cells take up nutrients and space that normal cells need.
This can damage tissues and organs and eventually lead to death.
These cells are cancer cells, growing out of control and forming a tumor.
https://docs.google.com/open?id=0B14yRRvSC2LPY2NjYmRlN2UtNTZiMS00YjY1
LThlNjgtZDNjNDU3ZTdlYTkz
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Cell division is part of the life cycle of virtually all cells. It is a
more complicated process in eukaryotic than prokaryotic cells
because eukaryotic cells have multiple chromosomes and a
nucleus.
The cell cycle is a repeating series of events that cells go
through. It includes growth, DNA synthesis, and cell division.
In eukaryotic cells, there are two growth phases, and cell
division includes mitosis.
The cell cycle is controlled by regulatory proteins at three key
checkpoints in the cycle. The proteins signal the cell to either
start or delay the next phase of the cycle.
Cancer is a disease that occurs when the cell cycle is no longer
regulated. Cancer cells grow rapidly and may form a mass of
abnormal cells called a tumor.