The Cell Cycle
&
Cell Division
The Cell Cycle
http://www.nobel.se/medicine/laureates/2001/press.html
Animated Cycle
http://www.cellsalive.com/cell_cycle.htm
MITOSIS
Mitosis
The process of cell division which results
in the production of two daughter cells
from a single parent cell.
The daughter cells are identical to
one another and to the original parent
cell.
Mitosis can be divided into stages
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase & Cytokinesis
Interphase
The cell prepares for division
• Animal Cell
– DNA replicated
– Organelles replicated
– Cell increases in size
• Plant Cell
– DNA replicated
– Organelles replicated
– Cell increases in size
Interphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Prophase
The cell prepares for nuclear division
• Animal Cell
– Packages DNA into
chromosomes
• Plant cell
– Packages DNA into
chromosomes
Prophase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Metaphase
The cell prepares chromosomes for
division
• Animal Cell
– Chromosomes line up
at the center of the cell
– Spindle fibers attach
from daughter cells to
chromosomes at the
centromere
• Plant Cell
– Chromosomes line up
at the center of the cell
– Spindle fibers attach
from daughter cells to
chromosomes at the
centromere
Metaphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Anaphase
The chromosomes divide
• Animal Cell
– Spindle fibers pull
chromosomes apart
– ½ of each
chromosome (called
chromotid) moves to
each daughter cell
• Plant Cell
– Spindle fibers pull
chromosomes apart
– ½ of each
chromosome (called
chromotid) moves to
each daughter cell
Anaphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Telophase
The cytoplasm divides
• Animal Cell
– DNA spreads out
– 2 nuclei form
– Cell membrane
pinches in to form
the 2 new
daughter cells
• Plant Cell
– DNA spreads out
– 2 nuclei form
– New cell wall forms
between to nuclei to
form the 2 new
daughter cells
Telophase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
II. The “C” Words in Mitosis
A. Chromatin
1. DNA + protein - found in nucleus of
a non-dividing cell
B. Chromatid
1. one of two identical parts of a
chromosome in a mitotic cell
2. sister chromatids are identical
a. same DNA and the same genes
C. Centromere
1. holds sister chromatids together
2. attaches chromosome to spindle fibers
D. Centrosomes
1. found in plant and animal cells
2. spindle fibers radiate from a pair of
these during mitosis
E. Centrioles
1. found in the centrosomes of animal
cells only
2. one pair in each centrosome
REVIEW THE CELL CYCLE
A. Interphase
1.G1- cells grow & mature(time between)
between division and DNA replication)
2.G0 - DNA does not replicate (cell will
not divide)
S – DNA replicates
3.G2 – cell prepares for division if the
DNA does replicate (cell will divide)
Cell Cycle
The Cell Cycle
B. Mitosis
1. Prophase
a. chromosomes become visible
b. centrosomes appear, separate and
move toward poles
c. spindle appears
d. nucleolus and nuclear membrane
disappear
Interphase
Prophase
2. Metaphase
a. chromosomes line up at equator
3. Anaphase
a. centromeres divide
b. sister chromatids separate
1) considered individual chromosomes
c. chromosomes begin to move apart
d. chromosomes move to opposite poles
Metaphase
Anaphase
Late
4. Telophase
a. chromosomes reach the poles
b. spindles disappear
c. nuclear membrane and nucleolus
reappear in each cell
d. chromosomes become less distinct
e. cytokinesis begins
Metaphase Interphase TelophaseCytokinesis
C. Cytokinesis
1. a cleavage furrow develops in animal
cells - a cell plate forms in plant cells
2. two distinct daughter cells form
3. daughter cells enter interphase
4. offspring cells have identical copies
of chromosomes and ½ the original
cell cytoplasm and organelles
Mitosis Animation
http://www.cellsalive.com/mitosis.htm
Events during Mitosis
mitosis
Interphase: Cells may appear inactive during this stage, but they are quite the opposite.
This is the longest period of the complete cell cycle during which DNA replicates, the
centrioles divide, and proteins are actively produced. For a complete description of the
events during Interphase, read about the Cell Cycle.
Prophase: During this first mitotic stage, the nucleolus fades and chromatin (replicated
DNA and associated proteins) condenses into chromosomes. Each replicated
chromosome comprises two chromatids, both with the same genetic information.
Microtubules of the cytoskeleton, responsible for cell shape, motility and attachment to
other cells during interphase, disassemble. And the building blocks of these
microtubules are used to grow the mitotic spindle from the region of the centrosomes.
Prometaphase: In this stage the nuclear envelope breaks down so there is no longer a
recognizable nucleus. Some mitotic spindle fibers elongate from the centrosomes and
attach to kinetochores, protein bundles at the centromere region on the chromosomes
where sister chromatids are joined. Other spindle fibers elongate but instead of
attaching to chromosomes, overlap each other at the cell center.
MITOSIS
Metaphase: Tension applied by the spindle fibers aligns all chromosomes in one plane at
the center of the cell.
Anaphase: Spindle fibers shorten, the kinetochores separate, and the chromatids
(daughter chromosomes) are pulled apart and begin moving to the cell poles.
Telophase: The daughter chromosomes arrive at the poles and the spindle fibers that
have pulled them apart disappear.
Cytokinesis: The spindle fibers not attached to chromosomes begin breaking down until
only that portion of overlap is left. It is in this region that a contractile ring cleaves the cell
into two daughter cells. Microtubules then reorganize into a new cytoskeleton for the
return to interphase.
Cancer cells reproduce relatively quickly in culture. In the Cancer Cell CAM compare the
length of time these cells spend in interphase to that for mitosis to occur.
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase