AP BIOLOGY

CELL DIVISION

THE CELL CYCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
When does the following take place:Spindle fibers attach to the centromeres of chromosomes and line them up along the middle of the cell.
A
Metaphase
B
Anaphase
C
Prophase
D
Telophase
Explanation: 

Detailed explanation-1: -Metaphase. During metaphase, spindle fibers attach to the centromere of each pair of sister chromatids (see Figure below). The sister chromatids line up at the equator, or center, of the cell. This is also known as the metaphase plate.

Detailed explanation-2: -Long protein fibers called microtubules extend from the centrioles in all possible directions, forming what is called a spindle. Some of the microtubules attach the poles to the chromosomes by connecting to protein complexes called kinetochores.

Detailed explanation-3: -In prophase of mitosis, specialized regions on centromeres called kinetochores attach chromosomes to spindle fibers. The centromere is the part of a chromosome that links sister chromatids. During mitosis, spindle fibers attach to the centromere via the kinetochore.

Detailed explanation-4: -Metaphase is defined as the point at which all of the chromosome pairs are fully condensed, attached to the mitotic spindle, and aligned at the center-termed the metaphase plate.

Detailed explanation-5: -During metaphase, the cell’s chromosomes align themselves in the middle of the cell through a type of cellular “tug of war.” The chromosomes, which have been replicated and remain joined at a central point called the centromere, are called sister chromatids.

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