Transcript Cell Division

The Cell Cycle
the amazing! incredible! I-can’t –wait-tohear-more story of how cells divide
Stages of the Cell Cycle
INTERPHASE
• G1 phase: The period prior to the synthesis of DNA when cells do most
of their growing. In this phase, the cell increases in mass in preparation
for cell division. Note that the G in G1 represents gap and the 1
represents first, so the G1 phase is the first gap phase.
• S phase: The period during which DNA is synthesized and
chromosomes are replicated. In most cells, there is a narrow window of
time during which DNA is synthesized. Note that the S represents
synthesis.
• G2 phase: The period after DNA synthesis has occurred but prior to the
start of prophase. The cell synthesizes proteins and continues to
increase in size; many of the organelles and molecules required for cell
division are produced. Note that the G in G2 represents gap and the 2
represents second, so the G2 phase is the second gap phase. When
the G2 is completed the cell is ready to enter the M phase and begin the
process of cell division.
In the latter part of interphase, the cell still has
nucleoli present.
The nucleus is bounded by a nuclear envelope
and the cell's chromosomes have duplicated but
are in the form of chromatin.
In animal cells, two pair of centrioles formed from
the replication of one pair are located outside of
the nucleus.
PROPHASE
• Longest stage of mitosis
• Chromatin condenses into
chromosomes
• Centrioles separate and go to
opposite poles
• Spindle begins to form from
microtubules
• Nuclear envelope begins to
break down
• Chromosomes split into two
parts called chromatids
connected at the centromere
Prophase
Interphase
METAPHASE
•
•
•
Spindle fibers arch
across cell between the
centrioles
Chromosomes line up
across the equator of the
cell
Chromosomes attach to
spindle fibers at the
centromere
ANAPHASE
• Centromeres duplicate
and split
• Sister chromatids
separate and become
individual chromosomes
• Spindle fibers begin to
pull chromosomes to the
poles
• Anaphase ends when
chromosomes stop
moving
TELOPHASE
• Final phase of mitosis
• Cell begins to pinch in the center splitting the cell
into two daughter cells
• Duplicated cytoplasmic organelles are equally
distributed into each new cell
• Spindles disappear and centrioles lose their
asters
• Chromosomes begin to disperse forming
chromatin
• Nuclear membrane reforms and nucleolus
become visible in each daughter nucleus
MID-TELOPHASE
LATE TELOPHASE
CYTOKINESIS
•
•
•
•
•
•
M phase of cell cycle
Two nuclei are present
Duplicated organelles
present in cytoplasm
Final cytoplasmic
division occurs as cell
membrane continues to
pinch in to center of animal
cells
In plant cells, cell plate forms
midway between nuclei and
gradually develops into a
separating membrane; cell
wall begins to appear
Cytokinesis usually occurs at the
same time as telophase
Cytokinesis- Animal Cell
Mitosis 3
rap it up
CELL REGULATORS
Proteins=
• Internal
• External