Question

At the molecular level, what is a gene? Where are genes located?

Short answer

A gene is a segment of DNA containing instructions for building proteins. They are located on chromosomes which reside inside the nucleus of animal and plant cells.

Step-by-step solution

Understanding what a gene is at the molecular level

A gene is a segment of DNA that contains the instructions for building one or several proteins. These proteins are important for body's structure, function, and regulation of body's tissues and organs. Each protein has a unique role. In order to build these protein, the DNA sequence of a gene is copied into RNA, a process called transcription. The RNA then goes through translation, where its sequence is used to build a protein molecule.

Describing where genes are located

Genes are located on chromosomes. Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of DNA. Humans have about 20,000-25,000 genes, scatter over 23 pairs of chromosomes, amounting to 46 in total.