Final answer:
The correct structures that attach chromosomes to spindle fibers are kinetochore microtubules, which are part of the mitotic spindle formed from the centrosomes and attach to the kinetochore in the centromeric region of chromosomes.
Step-by-step explanation:
The structures that attach chromosomes to spindle fibers during mitosis are the kinetochore microtubules, which are a part of the overall mitotic spindle. These microtubules attach to a protein structure called the kinetochore, which is found in the centromeric region of each sister chromatid. This connection forms during the prometaphase stage of mitosis, following the dissolution of the nuclear envelope. The mitotic spindle is primarily formed from the centrosomes, and it also contains polar microtubules that overlap at the cell center but do not attach to kinetochores.
Two Kinds of Spindle Fiber Microtubules
- Kinetochore Microtubules: Attach to kinetochores of sister chromatids for chromosome segregation.
- Polar Microtubules: Overlap with each other at the cell center and facilitate the cell elongation during anaphase.
Therefore, in response to the student's question, the correct answer is C. Microtubules. For the fill-in-the-blank references, the correct answers are b) centrosome, and spindle microtubules attach to centromeres during mitosis.