If I started like that, how
did I get to this?
CELL CYCLE
• Over time, organisms grow; many cells die and need to
be replaced.
• The process in a cell’s life cycle when it reproduces to
create two identical cells is called mitosis.
Cells formed during
mitosis are known as
daughter cells.
The cell division process occurs as four different stages,
known collectively as the 'cell cycle'.
Cell Cycle
• The cell cycle consists of four stages
– G1 (Growth 1 Phase)
– S (Synthesis Phase)
– G2 (Growth 2 Phase)
– M (Mitotic Phase)
• The first three phases, as a group, are called
Interphase. Cells spend the majority of their life in
this stage.
Cell Cycle
• Interphase - G1 ‘Gap/Growth' phase in which the cell
grows and duplicates internal organelles (not DNA).
Cell Cycle
• Interphase - S is the phase when new DNA is
synthesized through DNA replication.
Cell Cycle
• Interphase – G2 ‘Gap/Growth' phase in which the cell
grows and checks duplicated DNA for any errors.
Cell Cycle
• Mitosis - M is the mitotic phase in which the cell
physically divides into two daughter cells.
Mitosis
• Mitosis is a process where cells are produced for
growth and/or replacing damaged or old cells
• Mitosis has four sub-phases:
– Prophase
– Metaphase
– Anaphase
– Telophase
PROPHASE
• Chromosomes condense, the nuclear membrane
breaks down, and spindle fibers form from centrioles.
METAPHASE
• Replicated chromosomes line up in the middle of the cell.
• Spindle fibers attach to the centromere of each
chromosome.
ANAPHASE
• Chromosomes begin to be pulled apart, and the cell
becomes elongated, with distinct ends (poles).
TELOPHASE
• Nuclear envelope/membrane re-forms around the
separated chromosomes and cell membrane begins
to create two independent cells.
CYTOKINESIS
The final division of the cytoplasm that completes the
process of mitosis and makes two complete daughter
cells.
• ANIMAL CELLS
– Cell membrane pinches in to create
two equal parts with one nucleus in
each daughter cell.
• PLANT CELLS
– Cell plate forms down center of cell
between the two nuclei and creates a
new cell wall
Animations
http://www.johnkyrk.com/mitosis.html
http://www.hybridmedicalanimation.com/anim_m
itosis.html
Regulating the Cell Cycle
Proteins called cyclins regulate the timing of the cell cycle.
– These proteins “tell” the cell when it is time to
divide.
Cancer - disorder when cells lose the ability to control
their growth and form clusters of irregular cells called
tumors.
Cancer & The Cell Cycle
Normal vs. Cancer Cell Growth
METAPHASE
CYTOKINESIS
PROPHASE
ANAPHASE