The centromere is a region at which ________.
a. Sister chromatids are attached to each other.
b. Metaphase chromosomes align.
c. The tips of chromosomes are found.
d. The nucleus is located.

Verified step by step guidance

1. Step 1: Understand the term 'centromere'. The centromere is a specialized region of a chromosome that plays a critical role during cell division. It is the point where sister chromatids are held together and where spindle fibers attach during mitosis and meiosis.
2. Step 2: Analyze the options provided in the question. Each option describes a different part or function of a chromosome or cell structure. You need to identify which one correctly matches the definition and function of the centromere.
3. Step 3: Evaluate option (a): 'sister chromatids are attached to each other'. This matches the definition of the centromere, as it is the region where sister chromatids are physically connected.
4. Step 4: Evaluate option (b): 'metaphase chromosomes align'. This describes the metaphase plate, not the centromere. The metaphase plate is where chromosomes line up during metaphase of cell division.
5. Step 5: Evaluate options (c) and (d): Option (c) refers to the tips of chromosomes, which are called telomeres, and option (d) refers to the nucleus, which is a separate organelle. Neither of these options is related to the centromere.

Key Concepts

Centromere Function

The centromere is a specialized region of a chromosome that plays a crucial role during cell division. It is the point where sister chromatids are held together, ensuring proper segregation into daughter cells during mitosis and meiosis. The centromere is essential for the formation of the kinetochore, a protein structure that attaches to spindle fibers.

Sister Chromatids

Sister chromatids are identical copies of a single chromosome that are created during DNA replication. They remain attached at the centromere until they are separated during cell division. This separation is vital for ensuring that each daughter cell receives an accurate and complete set of chromosomes.

Metaphase Alignment

During metaphase, chromosomes align at the cell's equatorial plane, known as the metaphase plate. This alignment is critical for the equal distribution of chromosomes to the daughter cells. The centromere's role in holding sister chromatids together is essential for this process, as it ensures that each chromatid is pulled to opposite poles of the cell.