Transcript The Cell Cycle - Cloudfront.net

10-2 The Cell
Cycle
I. Prokaryote Cell
Division
A. A prokaryote cell divides
by binary fission.
1. DNA copies itself.
2. Cell grows and begins to
divide.
3. New cell wall forms and
two new cells are formed.
4. 2 cells are identical to
original.
II. Cell Division’s
A. Mitosis: body cell division
resulting in two cells with
identical genetic material
1. 46 chromosomes to 46
B. Meiosis: reproductive cells
reducing the number of
chromosomes by half from
46 to 23 chromosomes.
1. Also called Reduction
Division.
III. The Cell Cycle
A. The repeating set of events
that make up the life of a cell.
1. Interphase, G1, S, G2
phases
2. M phase: the dividing
phase, prophase, metaphase,
anaphase, telophase.
3. Cytokinesis: division of
cytoplasm of a cell
IV. Interphase: Non-dividing
phase
A. G1 phase: offspring cells grow
to mature size
B. S phase: cell’s DNA is copied
C. G2 phase: cell prepares for
division
D. G0 phase: cells not dividing or
preparing for division, brain cells.
Early Interphase
The M- Phase
1. Prophase
A. DNA tightens into rodshaped chromosomes.
B. Centromere connects the
two sister chromatids
C. Nucleolus and nuclear
membrane disappears
D. Centrosomes- dark spots
that appear next to the
disappearing nucleus,
containing a pair of cyclinder
shaped bodies called
centrioles, (animals cells
only)
E. Spindle fibers radiate from
the centromeres and form
the mitotic spindle
1. This equally divides the
chromatids.
F. 2 kinds of Spindle Fibers
1. Kinetochore fibers
attach to a protein called
kinetochore found in the
centromere region, and
move the chromosomes
2. Polar fibers extend
across the dividing cell
from one centrosome to
the other centrosome.
Prophase
2. Metaphase
A. Kinetochore fibers
move the chromosomes
to the center of the
dividing cell
1). Chromosomes are
easily seen lined up in
the middle of the cell
Metaphase
3. Anaphase
A. Sister chromatids
separate at the centromere
and move toward opposite
ends of the cell
1). They are pulled
centromere first, making it
look like they are being
dragged.
Early Anaphase
Late Anaphase
4. Telophase
A. Chromosomes are now
at opposite ends
1). Spindle fibers
disassemble.
2). Chromosomes relax
and turn into chromatin.
3). Nuclear envelope and
nucleolus reforms.
Telophase
5. Cytokinesis
A. Dividing of the cytoplasm
1). Cleavage furrow forms
between the two poles of an
animal cell.
2). This pinches the cell into
two.
3). In plants, a cell plate or
wall forms from vesicles,
separating the two halves.