As a field expert in molecular biology, I am well-versed in the intricacies of genetic material and its role in the continuity of life. DNA, or deoxyribonucleic acid, is the fundamental molecule of heredity in all known living organisms and many viruses. It carries the genetic instructions used in the development and functioning of all known living organisms and many viruses. DNA is a molecule that is composed of two chains that coil around each other to form a double helix, a structure that was first described by James Watson and Francis Crick in 1953.

DNA is not visible as a single strand to the naked eye, but when thousands of threads of DNA are present, they form a structure that can be observed under a microscope. This is because DNA is a very long molecule, and when it is coiled and condensed into chromosomes, it becomes visible to the human eye. In a single human cell, there are approximately 2 meters of DNA, which, if stretched out, would be long enough to reach from New York to Los Angeles.

The statement that DNA is found in all living or once living cells is accurate. DNA is present in every cell of an organism, from the moment of its conception until the moment of its death. It is the blueprint for the organism's development, growth, and reproduction. In multicellular organisms, every cell contains the same DNA, but different cells express different parts of that DNA to perform different functions.

In addition to living organisms, DNA is also found in the remnants of once living things. For example, ancient DNA can be extracted from fossils and other preserved biological materials, providing valuable insights into the evolutionary history of species. This ancient DNA can be analyzed to understand the genetic relationships between extinct and extant species, as well as to reconstruct the genetic makeup of organisms that lived in the distant past.

Furthermore, DNA is not only found within the cells of organisms but also in the mitochondria and chloroplasts, which are organelles that have their own DNA. Mitochondrial DNA, for instance, is inherited maternally and is often used in tracing ancestry and evolutionary studies.

The presence of DNA is a testament to the universality of the genetic code and its critical role in the biology of life. It is the molecule that holds the secrets of life's diversity and the potential for life's future. Understanding DNA is crucial for advancing our knowledge of genetics, evolution, and the development of new medical and biotechnological applications.

read more >>

DNA is not visible as a single strand to the naked eye, but when thousands of threads of DNA are present, you will be able to see the large groups of threads of DNA. 5. Is DNA found in all living or once living cells? Yes, DNA is present in all living and once living cells.read more >>