Phragmoplast (PP)
A cytokinetic array of antiparallel microtubules (MT) organized perpendicularly to the division plane, coexisting with an array of actin filaments
Formed after the PPB —> during the anaphase-to-telophase transition of cell division
What does the PP control during cytokinesis?
During cytokinesis, the cytoskeletal PP controls the cell plate assembly.
Cortical division zone (CDZ)
The plasma membrane region occupied by the preprophase band (PPB) and division site resident proteins, which delineates the division plane.
Division plane
The plane where the cell plate is assembled.
Formed after prometaphase (after PPB formation)
—> Chromosome segregation
Preprophase band (PPB)
Highly organized cytoskeletal array, foreshadowing the circumference of the division plane
PPB disappears at about the time of the nuclear envelope breakdown at prometaphase
Outlines the position of the
Formed during the G2 phase
Found from preprophase to late prophase/prometaphase
Despite its disintegration at late prophase/prometaphase, a set of proteins initially tethered to the PPB remains at the adjacent plasma membrane region and designates the division site —> CDZ
Division site
Collectively refers to the cortical division zone in mitosis and the cell plate fusion site in cytokinesis
Preprophase band (PPB) contains…
Microtubules (MT)
Actin filaments (AF)
Organelles
Proteins
Cell plate fusion site
The site at the plasma membrane where the developing cell plate fuses.
Which are the 2 major events during plant cytokinesis?
Determination of the cell division plate
Assembly of the cell division plate
Actin-depleted zone (ADZ)
A region at the cortical cytoplasm of the parental plasma membrane with fewer actin filaments, potentially coinciding with the cortical division zone
temporarily.
How do proteins in the division site promote their functionalities?
Among the residents of the division site, some proteins contribute to the maintenance and guidance of the phragmoplast and cell plate, whereas other proteins mediate the anchoring of the cell plate to the parental plasma membrane at the division site.
Which is the difference between animal and plant cell division, as far as the temporal establishment of the division plane is concerned?
Animal cells select their division plane in metaphase and anaphase.
Most plant cells earmark their division plane by the preprophase band (PPB) at the G2/M transition - much earlier when compared to the animal cells
Top 4 stages of cell plate assembly
Accumulation and fusion of vesicles
Tubulovesicular network
Tubular network
Fenestrated sheet
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