Download Mitosis makes DIPLOID cells

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 Cell Cycle
http://www.cellsalive.com/mitosis.htm
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
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chromatin: uncoiled DNA(noodles)
chromatid: single, coiled piece of DNA, 1/2 a
chromosome (dreadlock)
chromosome: X-shaped pair of identical DNA
pieces
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Homologous pairs: a set of two chromosomes (one from
each parent) that have the same genetic traits but
different versions
Diploid: a cell with all necessary homologous pairs
Haploid: a cell with no homologous pairs
Note: Mitosis makes DIPLOID cells
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)
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G1, S, and G2 phases occur
Chromosomes are copied in S phase
DNA appears as threadlike chromatin
Cell is doing its “day job” and maintaining
homeostasis (staying alive)
Nucleus
CELL
MEMBRANE
Cytoplasm
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis begins (divide nucleus and DNA)
• Centrioles (animal cell only) move to opposite
end of the cell.
• Spindle fibers form
• DNA - Chromatin becomes rod-like chromatids
that combine with copy to form X-shaped
chromosomes
•
Centrioles
Chromosomes
Spindle fibers
Animal Cell
Plant Cell
Spindle fibers
Centrioles
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
•
Chromosomes attach to the spindle fibers in
the middle single-file
Centrioles
Spindle fibers
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Chromosomes are pulled apart to opposite
ends of the cell.
• Each side now has a single copy of each
chromatid
•
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.
Chromatids uncoil to form chromatin (threads
rather than rods).
Mitosis ends.
Nuclei
Chromatin
Nuclei
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
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The rest of the cell splits to create two
daughter cells – each with its own nucleus
and identical chromosomes.
Plant Cells – new cell wall forms called a cell
plate
Animal cells – pinches inward to form a
cleavage furrow
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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
Interphase
(G1, S, G2)
Mitosis
Prophase
Metaphase
Anaphase
Telophase
 Cytokinesis

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
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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
chromatids 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?
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