Multiple Choice
During mitosis, what cellular structure is primarily responsible for moving chromosomes to opposite poles of the cell?
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15. Cytoskeleton and Cell Movement
Microtubules and Cell Division
Multiple Choice
In mitosis, what is the primary role of spindle fibers (microtubules) during metaphase and anaphase?
A
They form the cleavage furrow by contracting actin and myosin to divide the cytoplasm.
B
They synthesize new nuclear envelopes around the separated chromosomes at the end of mitosis.
C
They replicate the cell's DNA to ensure each daughter cell receives an identical genome.
D
They attach to kinetochores and separate sister chromatids by pulling them toward opposite poles of the cell.
Verified step by step guidance1
Understand that spindle fibers are composed of microtubules, which are dynamic structures essential for chromosome movement during mitosis.
During metaphase, spindle fibers attach to the kinetochores, which are protein complexes located at the centromere of each sister chromatid.
The spindle fibers align the chromosomes along the metaphase plate (the cell's equatorial plane), ensuring that each sister chromatid is properly oriented toward opposite poles.
In anaphase, the spindle fibers shorten by depolymerizing, which generates the force needed to pull the sister chromatids apart toward opposite poles of the cell.
Recognize that this separation ensures that each daughter cell will receive an identical set of chromosomes, which is critical for genetic stability.
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