Illustration of chromosome structure and components within a cell.

To solve the problem, we need to label the structures in the provided diagram using the words from the box: DNA, Gene, Centromere, Chromosome, Nucleus, and Cell. Let's analyze the diagram step by step:

Diagram Analysis:

1. Outermost Structure: This is the largest structure that encompasses everything inside. It represents the Cell.
2. Inner Structure with a Membrane: Inside the cell, there is a membrane-bound structure. This is the Nucleus, which contains the genetic material.
3. X-Shaped Structure Inside the Nucleus: This is a chromosome during cell division (mitosis or meiosis). The X-shape indicates that the chromosome has replicated and consists of two sister chromatids.
4. Central Point on the Chromosome: This is the Centromere, the point where the two sister chromatids are attached.
5. Coiled Structure at the Bottom: This is the DNA, which is the genetic material. DNA is shown as a double helix.
6. Smaller Segment on the DNA: This is a Gene, which is a specific segment of DNA that codes for a protein or RNA.

Labeling the Diagram:

- Outermost Structure: Cell
- Membrane-Bound Structure Inside the Cell: Nucleus
- X-Shaped Structure: Chromosome
- Central Point on the Chromosome: Centromere
- Coiled Structure at the Bottom: DNA
- Smaller Segment on the DNA: Gene

Final Answer:

```
Cell
Nucleus
Chromosome
Centromere
DNA
Gene
```

Thus, the labeled diagram would look like this:

```
Cell
|
Nucleus
|
Chromosome
|
Centromere
|
DNA
|
Gene
```

Final Answer:
\boxed{Cell, Nucleus, Chromosome, Centromere, DNA, Gene}