Our guide picked us up and entertained us the whole way, taking us to the best spots â we even had a close encounter with a bear on the side of the road! This wildlife photo tour will explore the wildlife, geology, and natural history of Grand Teton National Park.
Chromosomes contain smaller units of genetic material called DNA. DNA is a sequence of letters that spell out the genetic code. The DNA is organized into words and sentences called genes. Humans have approximately 20,000 genes and each one influences a part of development. These genes usually come in pairs.
In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.Chromosomes are not visible in the cellâs nucleusânot even under a microscopeâwhen the cell is not dividing.enes, which are made up of DNA, act as instructions to make molecules called proteins. In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases. The Human Genome Project has estimated that humans have between 20,000 and 25,000 genes.