Terms
Anaphase
-
The fourth stage of mitosis during which sister chromosomes are separated
and pulled to opposite ends of the cell by kinetochore
microtubules.
Contractile ring
-
A ring of protein filaments that encircles the region of the metaphase plate
in a dividing cell. Responsible for pinching the cell until it separates into
two independent cells.
Cytokinesis
-
The final part of M Phase, during which a cell with duplicated contents
splits into two independent cells.
Kinetochores
-
Sites on replicated, bound sister chromatids
to
which microtubules bind, thereby becoming kinetochore microtubules.
M phase
-
The name given to the five separate steps of mitosis and the final cleavage
of the cell in cytokinesis.
Metaphase
-
The third stage of mitosis during which kinetochore
microtubules* align sister
chromatids along the metaphase plate at
the center of the cell.
Metaphase plate
-
An imaginary line found half way between the two mitotic spindle poles on
which chromosomes align
during metaphase.
Microtubule
-
One of three protein components of the cytoskeleton. Long, cylindrical
structures approximately 25 nanometers in diameter. Extend from the
centrosome to all parts of
the cell, forming tracks on which organelles can travel within the cell.
Microtubules can be either kinetocore microtubules or non-kinetocore
microtubules. Kinetocore microtubules bind to sister
chromatids during
mitosis. Non-kinetocore microtubules are
broken down into two further categories: polar microtubules and astral
microtubules.
Mitosis
-
The five-step process by which a cell separates replicated chromosomes before
cytokinesis creates two identical daughter cells from one original cell.
The five steps of mitosis are: prophase, prometaphase, metaphase,
anaphase, telophase.
Mitotic spindle
-
A complex of microtubules that form between opposite poles of a cell during
mitosis. Serve to separate and move sister
chromatids to opposite ends of the cell for
division.
Prometaphase
-
The second stage of mitosis during which the nuclear envelope disassembles
and microtubules gain access to chromosome kinetochores.
Prophase
-
The first stage of mitosis, during which visibly dark, condensed
chromosomes are found in the
nuclear envelope.
Telophase
-
The fifth and final stage of mitosis before cytokinesis; in telophase,
the nuclear envelope re-forms around separated sister
chromatids and kinetochore
microtubules disappear. Cell elongation and decondensation of
chromosomes also occur.
