Download Spindle fibers

Asexual Reproduction
Mitosis
Mitosis is the process in which the nucleus
divides to form two new nuclei. After
cytokinesis, 2 cells are formed that are
identical to each other genetically, but 1/2
the size of the parent cell. How does mitosis
differ in plants and animals?
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How do little elephants grow up to be BIG
elephants?
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1. one parent
2. offspring identical to parent
3. occurs in unicellular organisms and
body cells as a part of growth.
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A technique that accomplishes the same result as asexual
reproduction. All offspring are identical to the parent because
they carry the same genetic code as the parent.
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plants - babies from spider plants are clones.
 - stem rooted in water that becomes a plant is a clone.
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Done by removing a nucleus (with the genetic information)
from a “parent” organism’s cell and inserting the nucleus into
an egg cell from which the nucleus has been removed. The
result is an egg that has 100% of the genetic information
from a single parent. The egg cell is then implanted and
develops inside of a female.
Cloning has been
accomplished in
sheep and pigs.
The process of asexual
reproduction in us 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.
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Mitosis is the process by which a cell’s genetic material
divides to create two sets of the cell’s genetic material. The
product is two cells with a full set of identical genes and
chromosomes, but the daughter cells are half the size of the
parent cell.
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Before mitosis can occur, the genetic information in the
DNA of the parent cell is duplicated exactly. During cell
division one copy is distributed to each cell.
› Cytokinesis follows mitosis. In cytokinesis the cell divides
the organelles and cytoplasm between the two new cells.
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Animated Mitosis Cycle
http://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
Chromosomes are copied
• Chromosomes appear as threadlike coils
(chromatin) at the start, but each chromosome
and its copy(sister chromosome) are called sister
chromatids at end of this phase
•
Nucleus
CELL
MEMBRANE
Cytoplasm
One chromosome
2 sister chomatids
Held by a
centromere
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Centrioles (or poles) appear and begin to
move to opposite end of the cell.
• Spindle fibers form between the poles.
• Chromosomes shorten and thicken
• Nuclear membrane and nucleoli disassemble
•
Centrioles
Sister chromatids
Spindle fibers
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Chromatids (replicated chromosomes) attach
to the spindle fibers at the centromere.
• Chromosomes line up at the equator
• Centrosome- Microtubule (spindle fibers)
organizing center.
•
Centrioles in
Centrosome area
equator
pole
pole
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromatids (replicated 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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Two new nuclei form.
Chromosomes appear as chromatin (threads
rather than rods).
Mitosis ends.
Nuclei
Chromatin
Nuclei
Animal Cell
Plant Cell
Cleavage furrow
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Cell plate
•
Cell membrane moves inward to create two
daughter cells – each with its own nucleus
with identical chromosomes. Animals divide
by a cleavage furrow and plants divide by
building a cell plate
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Cells
Animal Cells
Daughter cells contain the same
Number of chromosomes as the
parent cell
?
No Centrioles Present, spindle
forms
?
?
Daughter cells have about half
the cytoplasm of parent cell
?
Centrosome is present
Cytoplasmic division occurs by
formation of a cell plate
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- Cell Division
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11. What moves the chromatids during mitosis?
___________________________________
12. What anchors the spindle? ________________________________________
13. What are the four phases of mitosis?
___________________________________________________
14. How many daughter cells are created from mitosis and cytokinesis?
___________________________
15. During what phase does cytokinesis begin?
________________________________________
16. If a human cell has 46 chromosomes, how many chromosomes will be in each
daughter cell? _________
17. If a dog cell has 72 chromosomes, how many daughter cells will be created
during a single cell cycle? ______
.....Each of these daughter cells will have how many chromosomes? ____________
18. The nuclear membrane dissolves during what phase?
________________________
19. In the cell pictured above, how many chromosomes are present during
prophase? ________________
20. What structure holds the individual chromatids together?
______________________________
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11. What moves the chromatids during mitosis? Spindle fibers
12. What anchors the spindle? centrioles
13. What are the four phases of mitosis? prophase, metaphase,
anaphase, telophase
14. How many daughter cells are created from mitosis and
cytokinesis? two
15. During what phase does cytokinesis begin? telophase
16. If a human cell has 46 chromosomes, how many chromosomes
will be in each daughter cell? 46
17. If a dog cell has 72 chromosomes, how many daughter cells will
be created during a single cell cycle? 2
Each of these daughter cells will have how many chromosomes? 72
18. The nuclear membrane dissolves during what phase? prophase
19. In the cell pictured above, how many chromosomes are present
during prophase? 4
20. What structure holds the individual chromatids together?
centromere
http://www.cellsalive.com/mitosis.htm