How many of the following is observed in the interphase nucleus ?
Chromatid, Nucleosome, Centriole,
Nucleouls, Centromere, Kinetochore

Options

A. Three
B. One
C. Four
D. Two

Answer

To determine how many of the listed structures are observed in the interphase nucleus, we will analyze each component one by one.

1. **Chromatid**: During interphase, the DNA is in a relaxed state called chromatin, and individual chromatids are not visible. Chromatids become visible only during cell division (mitosis or meiosis). Therefore, chromatids are **not observed** in the interphase nucleus.

2. **Nucleosome**: A nucleosome is a structural unit of a eukaryotic chromosome, consisting of a segment of DNA wound around a core of histone proteins. While nucleosomes are present in the DNA, they cannot be observed under a microscope as distinct structures during interphase. Thus, nucleosomes are **not observed** in the interphase nucleus.

3. **Centriole**: Centrioles are organelles involved in cell division, specifically in the formation of spindle fibers. They are not present in the interphase nucleus as they are involved in the later stages of cell division. Therefore, centrioles are **not observed** in the interphase nucleus.

4. **Nucleolus**: The nucleolus is a prominent structure within the nucleus where ribosomal RNA (rRNA) is synthesized and ribosome assembly begins. The nucleolus is clearly visible during interphase. Thus, the nucleolus is **observed** in the interphase nucleus.

5. **Centromere**: The centromere is the constricted region of a chromosome that links sister chromatids. However, during interphase, chromosomes are not distinct and are not visible as individual entities, so the centromere is also **not observed** in the interphase nucleus.

6. **Kinetochore**: The kinetochore is a protein structure that forms on the centromere during cell division and is responsible for the movement of chromosomes. Since the centromere is not visible during interphase, the kinetochore is also **not observed** in the interphase nucleus.

**Summary**: Out of the six components listed, only the nucleolus is observed in the interphase nucleus. Therefore, the answer is **1**.