Reproduction
On this page 7 sections
Chromosome Type:
| Chromosome Type | Centromere Location | Relative Arm Lengths | Shape During Anaphase |
| Metacentric | Central (Middle) | Equal arms ($p = q$) | V-shape |
| Submetacentric | Sub-median (Off-center) | Unequal arms ($p < q$) | L or J-shape |
| Acrocentric | Near the very end | Minimal p-arm with satellites | I-shape / Rod-like |
| Telocentric | At the absolute tip | No p-arm | Rod-like |
Cell division process:
1. Kinetochores
- What it is: A specialized protein structure assembled on top of the centromere region of each chromosome.
- Function: It acts as the physical "docking site" or anchor point where the spindle fiber microtubules attach to pull the sister chromatids apart during mitosis.
2. Centromere
- What it is: The narrowed region of a chromosome where the two sister chromatids are held tightly together.
- Function: While this is the location on the DNA where everything happens, the spindle fibers don't attach directly to the naked DNA; they attach to the kinetochore proteins sitting on top of the centromere.
3. Microtubule
- What it is: Microscopic, hollow protein tubes made of tubulin that form the structural framework of the cell's cytoskeleton.
- Function: These are the spindle fibers themselves. The option is incorrect because the question asks what the chromatid attaches to (the kinetochore), rather than what the fiber is made of.
4. Centrioles
- What it is: Paired, barrel-shaped organelles located near the nucleus in animal cells.
- Function: They help organize the mitotic spindle. They migrate to opposite ends of the cell to form the centrosomes (the launching pads for the spindle fibers), but they are far away from the actual chromatids.
5. Poles
- What it is: The opposite ends/sides of the cell during division.
- Function: This describes the final destination where the chromosomes are being pulled. The spindle fibers radiate out from these poles to attach to the chromosomes in the center.