Molecular Cell Biology: Cell Cycle Metaphase Process

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Questions and Answers

How does the length of microtubules change during metaphase?

The length of microtubules changes due to the dynamic process of shortening and elongation, primarily by the loss or gain of tubulin subunits at the plus end.

What is the role of kinetochore microtubules during metaphase?

Kinetochore microtubules extend between the centrosomes and kinetochores of chromosomes, helping to align the chromosomes at the metaphase plate.

What is the role of astral microtubules during metaphase?

Astral microtubules radiate outward from the centrosomes and help in positioning the spindle apparatus within the cell, and may also determine the plane of cytokinesis.

Describe the behavior of the nuclear envelope during prometaphase.

<p>During prometaphase, the nuclear envelope breaks down or disassembles, allowing the spindle microtubules to access and capture the chromosomes.</p> Signup and view all the answers

What happens to the endoplasmic reticulum (ER) network during mitosis?

<p>The endoplasmic reticulum (ER) network undergoes fragmentation and reorganization during mitosis to facilitate its partitioning between the daughter cells.</p> Signup and view all the answers

How are cytoplasmic organelles partitioned during mitosis?

<p>Cytoplasmic organelles are partitioned randomly between the two daughter cells during mitosis, as there is no specific mechanism for their equal distribution.</p> Signup and view all the answers

What is the role of chromosomal microtubules during metaphase?

<p>The chromosomal microtubules exert a pulling force on the kinetochores to maintain the chromosomes in the equatorial plane by a 'tug-of-war' between balanced pulling forces from opposite spindle poles.</p> Signup and view all the answers

How do polar microtubules contribute to the mitotic spindle?

<p>Polar microtubules extend from the centrosomes past the chromosomes and overlap with their counterparts from the opposite pole. They help maintain the mechanical integrity of the spindle.</p> Signup and view all the answers

Describe the dynamic nature of microtubules during metaphase, even though they appear stationary.

<p>Even though the microtubules appear stationary at metaphase, injection of fluorescently labeled tubulin subunits indicates that the components of the spindle are in a dynamic state of flux or turnover.</p> Signup and view all the answers

What happens to the nuclear envelope during mitosis?

<p>The nuclear envelope breaks down or dissolves during prometaphase to allow the spindle microtubules to access and interact with the condensed chromosomes.</p> Signup and view all the answers

How are cytoplasmic organelles partitioned during mitosis?

<p>Cytoplasmic organelles are randomly distributed and partitioned between the two daughter cells during mitosis, primarily through their stochastic incorporation into one or the other cell.</p> Signup and view all the answers

What happens to the endoplasmic reticulum (ER) network during mitosis?

<p>The continuous ER network fragments into smaller vesicles and tubules during mitosis, which are then distributed to the daughter cells and reassemble into a new ER network.</p> Signup and view all the answers

What is the process of movement of chromosomes of a prometaphase cell toward the center of the mitotic spindle called?

<p>Congression</p> Signup and view all the answers

What is the role of motor proteins during prometaphase in relation to chromosome movements?

<p>Generating forces essential for chromosome movements.</p> Signup and view all the answers

How do kinetochores usually make initial contact with microtubules in the spindle?

<p>By contacting the side wall of a microtubule rather than its end.</p> Signup and view all the answers

What happens when microtubules connected to kinetochores from opposite poles differ in length?

<p>Imbalance is corrected by adjusting the length of microtubules.</p> Signup and view all the answers

What is the dynamic behavior observed in microtubule plus ends as they penetrate into the central region of a cell?

<p>They grow and shrink in a probing fashion.</p> Signup and view all the answers

How are chromosomes finally connected to microtubules from opposite poles during cell division?

<p>Through their kinetochores connecting to microtubules from opposite poles.</p> Signup and view all the answers

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