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The Cell Cycle
What is the cell cycle?
Just like you pass through different stages in your life, cells pass
through different stages in their lives. This is called the cell cycle.
How do prokaryotic cells
reproduce?
Prokaryotic cells are not as complex as eukaryotic cells. Prokaryotic
cells reproduce through a process called binary fission, which means
“splitting into two parts.” Binary fission results in two cells, each of
which has one copy of the circular DNA from the parent cell.
How do eukaryotic cells
reproduce?
Prokaryotic cells have just one chromosome, but eukaryotic cells have
many chromosomes. Eukaryotic cells have more DNA than
prokaryotic cells do. Because eukaryotic cells are complex, their
method of reproduction is also more complex. Reproduction in
eukaryotic cells takes place in three steps:
1. Interphase
2. Mitosis
3. Cytokinesis
What happens during
Interphase?
During Interphase, the cells grows and copies its organelles and
chromosomes. After each chromosome is duplicated, the two copies
are called chromatids. Chromotids are held together at the
centromere. The joined chromatids condense into an “X” shape. The
cell then enters the next stage of reproduction.
What is mitosis?
The second stage of the cell cyle is called mitosis. Mitosis is divided
into four steps:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
What happens during
prophase?
During prophase, the chromosomes
condense from long strands of DNA
into structures that look like rods.
What happens during
metaphase?
What happens during
anaphase?
What happens during
telophase?
During metaphase, the
membrane surrounding the
nucleus (nuclear membrane)
dissolves. The pairs of
chromosomes line up along the
equator of the cell.
During anaphase, the paired
chromatids separate and are
pulled to opposite ends of the
cell by the centrioles.
During telophase, a nuclear
membrane forms around each
set of chromosomes and the
chromosomes decondense. This
is the end of mitosis.
What is cytokinesis?
Cytokinesis is the last step
in cell reproduction. In a
cell without a cell wall, the
cell pinches in two and two
cells are formed. In a cell
that has a cell wall, a cell
plate forms and separates
the cells into two new cells.
Summary: The cell cycle describes the different stages that a cell goes through during its life. The
most important part of the cell cycle is cell reproduction. Cell reproduction takes place in three
steps: interphase, mitosis, and cytokinesis.