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Multiple Choice
The kinetochores are:
A
organelles responsible for ATP production in the cell
B
protein structures on the centromere where spindle fibers attach during cell division
C
membrane-bound sacs that store cellular waste
D
regions of DNA that encode ribosomal RNA
Verified step by step guidance
1
Understand the context of the question: The problem is asking about the function and location of kinetochores, which are structures involved in cell division. This requires knowledge of cell biology and mitosis.
Recall the role of kinetochores: Kinetochores are protein complexes that assemble on the centromere of a chromosome. Their primary function is to serve as attachment points for spindle fibers (microtubules) during cell division.
Eliminate incorrect options: (1) Kinetochores are not organelles responsible for ATP production; that is the role of mitochondria. (2) Kinetochores are not membrane-bound sacs; those are structures like lysosomes or vacuoles. (3) Kinetochores are not regions of DNA encoding ribosomal RNA; that is the function of nucleolar organizer regions.
Focus on the correct option: The correct description of kinetochores is that they are protein structures located on the centromere of chromosomes, where spindle fibers attach during mitosis and meiosis to ensure proper chromosome segregation.
Conclude with the biological significance: Kinetochores are essential for accurate chromosome alignment and separation during cell division, preventing errors like aneuploidy, which can lead to conditions such as Down syndrome or cancer.