A(n) is a segment of one strand of a DNA molecule.
The correct answer and explanation is:
Correct Answer: Gene
A gene is a segment of one strand of a DNA molecule. DNA, or deoxyribonucleic acid, is composed of two long strands that form a double helix. Each strand is made up of a sequence of nucleotides, which are the building blocks of DNA. These nucleotides include four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). The order of these bases along the DNA strand determines the genetic instructions used in the development and functioning of all living organisms.
A gene is defined as a specific sequence of bases that contains the instructions to make a functional product, usually a protein. Each gene occupies a fixed position, or locus, on a chromosome. While the entire DNA molecule contains all of the genetic material of an organism, only certain segments are genes. These segments are transcribed into messenger RNA (mRNA) and then translated into proteins through a process known as gene expression.
Genes vary in length and can consist of a few hundred to over two million base pairs. The human genome, for instance, contains approximately 20,000 to 25,000 genes. Not all DNA segments are genes; some portions are non-coding and serve regulatory or structural purposes.
Genes are inherited from parent to offspring, which allows genetic traits to be passed through generations. Mutations, or changes in the DNA sequence of a gene, can affect the function of the resulting protein, potentially leading to genetic disorders or variation in traits.
Understanding genes is fundamental in fields such as genetics, medicine, biotechnology, and evolutionary biology. By identifying and studying genes, scientists can better understand inherited diseases, develop gene therapies, and explore the mechanisms of life at a molecular level.