Tertiary Structure of DNA

In summary, the tertiary structure of DNA is the three-dimensional arrangement of the double helix and is formed by the folding and coiling of the double helix. It plays a crucial role in gene regulation and expression, allows for efficient packing of DNA, and can change due to external factors. It differs from the secondary structure in its complexity and involves interactions between different parts of the DNA molecule.
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Another God
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Can DNA be supercoiled while it is wrapped around Histones?

We are often shown in Biology classes electron Photographs of Supercoiled DNA. Would this DNA in the picture be completely free of Histones? Or could the DNA visualised in the picture be supercoiled DNA already in its condensed Nucleosome structure?
 
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I was under the impression that in vivo DNA that was wrapped around histones is predominately negatively supercoiled. Could be wrong.
 
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The tertiary structure of DNA refers to the folding and coiling of the double helix into a more compact and organized form. This is important for packing the large DNA molecules into the compact space of the cell nucleus. One of the major contributors to the tertiary structure of DNA is the presence of histones, which are proteins that act as spools around which the DNA is wrapped.

To answer the first question, yes, DNA can be supercoiled while it is wrapped around histones. In fact, this is the primary way in which DNA is organized in the cell. The DNA is first wrapped around histones to form nucleosomes, which are then further coiled and compacted to form chromatin fibers. These fibers can then be further coiled and condensed to form chromosomes.

The electron photographs of supercoiled DNA that are often shown in biology classes are most likely visualizing DNA in its condensed nucleosome structure. This is because the histones play a crucial role in maintaining the supercoiled structure of DNA. Without the presence of histones, the DNA would not be able to maintain its tightly coiled form. Therefore, it is safe to assume that the DNA in the picture is not completely free of histones.

In conclusion, the tertiary structure of DNA involves the wrapping of the double helix around histones to form nucleosomes, which can then be further coiled to form chromatin fibers. Supercoiled DNA can still be wrapped around histones and the electron photographs of supercoiled DNA most likely visualize DNA in its condensed nucleosome structure.
 

1. What is the tertiary structure of DNA?

The tertiary structure of DNA refers to the three-dimensional arrangement of the double helix. It is the highest level of organization of DNA and is responsible for its stability and function.

2. How is the tertiary structure of DNA formed?

The tertiary structure of DNA is formed by the folding and coiling of the double helix. This is due to the interactions between the nitrogenous bases, specifically hydrogen bonding, and the backbone of the DNA molecule.

3. What is the role of the tertiary structure of DNA?

The tertiary structure of DNA plays a crucial role in gene regulation and expression. It also allows for the efficient packing of DNA into the cell nucleus and protects the genetic information from damage.

4. How does the tertiary structure of DNA differ from the secondary structure?

The secondary structure of DNA refers to the double helix shape, while the tertiary structure includes the folding and coiling of the double helix. The tertiary structure is also more complex and involves interactions between different parts of the DNA molecule.

5. Can the tertiary structure of DNA change?

Yes, the tertiary structure of DNA can change due to external factors such as changes in temperature, pH, or the presence of certain enzymes. This can affect the function and stability of the DNA molecule.

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