Question 1

What are sister chromatids and when do they form?

Accepted Answer

Sister chromatids are identical copies of a chromosome created during DNA replication in the S phase of the cell cycle. Each chromatid contains the same genetic information and remains attached at a region called the centromere until cell division occurs, ensuring each daughter cell receives identical genetic material.

Question 2

Where do sister chromatids attach to each other?

Accepted Answer

Sister chromatids attach at the centromere, a specialized chromosomal region containing repetitive DNA sequences and associated proteins. This attachment point holds the two chromatids together throughout interphase and early stages of cell division until they separate during anaphase, maintaining chromosomal integrity.

Question 3

What proteins hold sister chromatids together at the centromere?

Accepted Answer

Cohesin proteins form a protein complex that holds sister chromatids together at the centromere and along chromosome arms. These cohesins maintain the attachment until anaphase, when they are cleaved by separase, allowing the chromatids to separate and move to opposite poles during mitosis and cytokinesis.

Question 4

Why is sister chromatid attachment important for cell division?

Accepted Answer

Sister chromatid attachment ensures that identical copies of genetic material are distributed equally to daughter cells during division. Proper attachment and subsequent separation prevent aneuploidy and maintain genetic stability across generations of cells, which is essential for organism growth and function.

Question 5

How do spindle fibers interact with attached sister chromatids?

Accepted Answer

Spindle fibers attach to sister chromatids at the kinetochore, a protein structure at the centromere. These fibers pull the attached chromatids toward opposite poles of the cell, and when cohesins are cleaved, the sister chromatids separate and move independently to ensure proper chromosome segregation.

Question 6

What happens if sister chromatids fail to attach properly?

Accepted Answer

Improper sister chromatid attachment can lead to unequal chromosome distribution during cell division, resulting in aneuploidy. This chromosomal imbalance can cause cell dysfunction, apoptosis, or in some cases contribute to cancer development, highlighting the critical importance of proper attachment mechanisms.

Attachment of Sister Chromatids

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