heres what i found:To understand chromatin, it is helpful to first consider chromosomes. Chromosomes are structures within the nucleus that are made up of DNA, the hereditary material. In prokaryotes, DNA is organized into a single circular chromosome. In eukaryotes, chromosomes are linear structures. Every eukaryotic species has a specific number of chromosomes in the nuclei of its body’s cells. For example, in humans, the chromosome number is 46, while in fruit flies, it is eight. Chromosomes are only visible and distinguishable from one another when the cell is getting ready to divide. When the cell is in the growth and maintenance phases of its life cycle, proteins are attached to chromosomes, and they resemble an unwound, jumbled bunch of threads. These unwound protein-chromosome complexes are called chromatin (Figure 3); chromatin describes the material that makes up the chromosomes both when condensed and decondensed. We will focus on chromatin and chromosomes in greater detail later.
Geologists can 'read' rock layers using relative and absolute dating techniques. ... Relative dating arranges geological events, and the rocks they leave behind, in a sequence. The method of reading the order is called stratigraphy (the rock layers are called strata).