17. CELL CYCLE
-is vital for growth; for repair
and replacement of damaged or worn
out cells; and for asexual
reproduction
-An orderly set of stages that take
place between the time a eukaryotic
cell divides and its daughter cells
divide
- DNA replication occurs
18. CELL CYCLE
- The life cycle of eukaryotic
cells, or cells containing a
nucleus, is a continuous process
typically divided into three phases
for ease of understanding:
INTERPHASE, MITOSIS, and
CYTOKINESIS
19. CELL CYCLE
INTERPHASE
-Where most of the cell cycle is
spent
-A time when the cell performs its
usual functions, depending on the
location in the body
+ G0 stage – stage wherein cells to
not complete the cell cycle and is
in permanent arrest
20. CELL CYCLE
G1 STAGE
-Stage before DNA replication
-The cell doubles its organelles
(mitochondria and ribosomes) and
accumulates materials for DNA
synthesis
21. CELL CYCLE
S STAGE
-DNA synthesis/replication occurs
resulting in duplicated chromosomes
-At the beginning, each chromosome
is composed of ONE DNA double helix
(CHROMATID)
-At the end, each chromosome has
two identical double helix
molecules
22. CELL CYCLE
G2 STAGE
-Stage from the completion of DNA
replication to the onset of mitosis
-The cell synthesizes protein that
will assist in cell division
23. CELL CYCLE
MITOTIC STAGE
-process in which a cell’s nucleus
replicates and divides in
preparation for division of the
cell
-results in two cells that are
genetically identical
-Occurs in 5 steps:
PROPHASE, PROMETAPHASE, METAPHASE,
ANAPHASE, and TELOPHASE
24. CELL CYCLE
Prophase
-the replicated, linked DNA strands
slowly wrap around proteins that
coil and condense into two
short, thick, rod-like structures
called chromatids, attached by the
centromere
-Two structures called
centrioles, both located on one
side of the nucleus, separate and
move toward opposite poles of the
cell
25. CELL CYCLE
Prophase
-As the centrioles move apart, they
begin to radiate
thin, hollow, proteins called
microtubules
-The microtubules arrange
themselves in the shape of a
football or spindle that spans the
area of the cell
26. CELL CYCLE
Prometaphase
-marked by the disintegration of
the nuclear membrane
-As the spindle forms, the nuclear
membrane breaks down into tiny sacs
or vesicles that are dispersed in
the cytoplasm
27. CELL CYCLE
Prometaphase
-The spindle fibers attach to the
chromatids near the
centromeres, and tug and push the
chromatids so that they line up in
the equatorial plane of the cell
halfway between the poles
-one chromatid faces one pole of
the cell, and its linked partner
faces the opposite pole
29. CELL CYCLE
Anaphase
-begins when the centromeres
split, separating the identical
chromatids into single
chromosomes, which then move along
the spindle fibers to opposite
poles of the cell
-At the end, two identical groups
of single chromosomes congregate at
opposite poles of the cell
30. CELL CYCLE
Telophase
-The final stage of mitosis
-a new nuclear membrane forms
around each new group of
chromosomes
-The spindle fibers break down and
the newly formed chromosomes begin
to unwind
31. CELL CYCLE
CYTOKINETIC STAGE
-final phase of the cell cycle
-The timing of cytokinesis varies
depending on the cell type
-the cell’s cytoplasm separates in
half, with each half containing one
nucleus
-Two identical daughter cells are
produced
