1. DNA (Deoxyribonucleic acid): This is the genetic material that carries the instructions for building and maintaining an organism. DNA is a long, double-stranded molecule that is twisted into a helix. Each strand is made up of a chain of nucleotides, which are composed of a sugar, a phosphate group, and one of four nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C). The order of these bases along the DNA strand is what determines the genetic information it carries.

2. Proteins: These are mainly histones, which are specialized proteins that help package and organize the DNA. Histones bind to DNA and help it coil and fold into a compact structure called chromatin. This structure is essential for fitting the long DNA molecule into the tiny nucleus of a cell.

In summary, chromosomes are essentially packages of DNA and proteins that are tightly coiled and condensed. These packages contain the genetic information that is passed down from one generation to the next.