Transcript Spindle fibers

Asexual Reproduction
Mitosis
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How do little elephants grow up to be BIG
elephants?
The process of asexual
reproduction begins after a
sperm fertilizes an egg.
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 Mitosis Cycle
http://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
Chromosomes are copied (# doubles)
• Chromosomes appear as threadlike coils
(chromatin) at the start, but each chromosome
and its copy(sister chromosome) change to sister
chromatids at end of this phase
•
Nucleus
CELL
MEMBRANE
Cytoplasm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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•
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Mitosis begins (cell begins to divide)
Centrioles (or poles) appear and begin to
move to opposite end of the cell.
Spindle fibers form between the poles.
Centrioles
Sister chromatids
Spindle fibers
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.
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromatids (or pairs of chromosomes)
separate and begin to move to opposite
ends of the cell.
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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•
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Two new nuclei form.
Chromosomes appear as chromatin (threads
rather than rods).
Mitosis ends.
Nuclei
Chromatin
Nuclei
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Cell membrane moves inward to create two
daughter cells – each with its own nucleus
with identical chromosomes.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
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- Cell Division
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A cell grows, prepares for division, and
divides to form 2 daughter cells
 FOUR phases:
1. G1 (gap 1)
2. S phase (synthesis,
DNA replication)
3. G2 (gap 2)
4. M phase (mitosis)


Interphase
(G1, S, G2)
Mitosis
Prophase
Metaphase
Anaphase
Telophase
 Cytokinesis

chromosome: X-shaped coiled piece of
two identical DNA pieces
 chromatid: individual pieces of coiled
DNA (1/2 of the X)

Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
two daughter cells have identical copies
of the parent cell’s DNA
 # of chromosomes is the same in both
cells (called the diploid #)


A microscope was used to examine
onion root tips. 4 different fields (A, B, C,
and D) were used. In each field, the cells
in the mitotic phases were identified and
counted. Cells in interphase were also
counted. What does this data reveal?
Area A Area B Area C Area D Total
Interphase
30
23
34
22
109
Prophase
3
4
3
2
12
Metaphase
6
3
2
4
15
Anaphase
3
1
2
1
7
Telophase
0
2
1
1
4
A human cell has 46 individual
chromosomes in its cells. After the S
phase of the cell cycle, how many
chromosomes will the cell contain?
 How many homologous (or matching)
pairs of chromosomes will the cell have
at prophase?
