metaphase chromosome alignment

Definition

Target type: biologicalprocess

A chromosome localization process whereby chromosomes are positioned in a specific order and orientation at the metaphase plate (spindle equator), during chromosome segregation. This alignment ensures that each daughter cell will receive the correct number of chromosomes during cell division. [GOC:vw]

Metaphase chromosome alignment is a critical step in cell division, ensuring that each daughter cell receives a complete set of chromosomes. This process involves the precise arrangement of chromosomes along the metaphase plate, an imaginary plane equidistant from the two spindle poles. Here's a detailed description:

1. **Spindle Fiber Formation:** During prophase and prometaphase, microtubules emanating from the centrosomes at opposite poles of the cell form the mitotic spindle. These microtubules extend towards the chromosomes, attaching to specialized structures called kinetochores located at the centromeres of each chromosome.
2. **Kinetochore-Microtubule Attachment:** Microtubules from opposite poles attach to the kinetochores of each sister chromatid, creating a bipolar attachment. This ensures that each chromatid is pulled towards a different pole.
3. **Congression:** Chromosomes are moved by the spindle fibers towards the metaphase plate. This movement involves a complex interplay of forces:
- **Microtubule Depolymerization:** Microtubules attached to the kinetochore shorten, pulling chromosomes towards the poles.
- **Microtubule Polymerization:** Microtubules at the poles elongate, pushing the chromosomes towards the center.
- **Motor Proteins:** Motor proteins associated with microtubules and the kinetochores contribute to the movement of chromosomes.
4. **Metaphase Plate Alignment:** As chromosomes are drawn towards the metaphase plate, they experience a "tug-of-war" from the spindle fibers attached to their kinetochores. This tension eventually aligns all chromosomes along the metaphase plate, ensuring that each chromosome is properly attached to microtubules from both poles.
5. **Checkpoint Control:** The cell has a built-in checkpoint mechanism that monitors the alignment of chromosomes. Only when all chromosomes are properly aligned at the metaphase plate does the cell receive the signal to proceed to anaphase.
6. **Anaphase Initiation:** Upon successful checkpoint evaluation, the sister chromatids separate, marking the beginning of anaphase. The microtubules shorten, pulling the separated chromatids towards opposite poles, leading to the segregation of chromosomes.

Metaphase chromosome alignment is a highly regulated process, essential for the proper distribution of genetic material to daughter cells during cell division. Errors in this process can lead to aneuploidy, a condition where cells have an abnormal number of chromosomes, which can contribute to various diseases, including cancer.'
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Proteins (2)

Compounds (8)