Indicate whether each of the following statements is true or false. If a statement is false, write in the correct statement. ______ Each chromosome has exactly 23 genes.

Human genetics is the scientific study of inherited human variation. It encompasses the patterns of gene transmission from parents to offspring, the molecular structure and function of genes, the actions of genes in the context of development and physiology, and the genetic basis of traits and disease. Understanding human genetics is crucial because it helps explain how certain characteristics are passed down, and why some individuals are predisposed to certain diseases.

In terms of chromosome composition, every human cell contains 23 pairs of chromosomes, inherited from both parents. 22 of these pairs are known as autosomes and are common to both sexes. The 23rd pair are the sex chromosomes, which determine the biological sex of an individual; females have two X chromosomes, while males have one X and one Y chromosome. Within these chromosomes lie tens of thousands of genes, which vary widely in number from one chromosome to another, contrary to the mistaken belief that there are a fixed number - 23 - of genes per chromosome.

The structure of DNA is fundamental to its role in storing and transmitting genetic information. DNA's structure is often described as a double helix, resembling a twisted ladder. The sides of this 'ladder' are composed of alternating sugar and phosphate groups, while the rungs consist of nitrogenous base pairs - adenine (A) paired with thymine (T), and guanine (G) paired with cytosine (C).

These base pairs are held together by hydrogen bonds, and the sequence of these bases along the DNA molecule encodes the genetic information needed for the construction and regulation of organisms. The double-stranded nature of DNA enables replication and repair, processes crucial in maintaining genetic integrity as cells divide and grow.

Genetic information is coded within the DNA of an organism and is expressed through the synthesis of proteins, which carry out the vast majority of cellular functions. This information is sequenced in the form of genes. A gene is a length of DNA that contains the code, or recipe, for making a specific protein; proteins, in turn, are responsible for specific traits and functions within an organism.

Gene expression involves two main processes: transcription and translation. During transcription, a particular segment of DNA is copied into RNA (specifically mRNA), which is then translated into a protein in the ribosomes. Each gene's code includes regions that determine when the gene is active (or 'expressed'), how much protein it makes, and other regulatory aspects that are essential for the precise control of gene activity necessary for normal growth, development, and maintenance of the organism.