What Are the Components of DNA?

DNA is a long molecule composed of two chains of smaller molecules called nucleotides, each which con DNA is a long molecule composed of two tain a region of nitrogen called the nitrogenous base, a carbon-based sugar molecule called deoxyribose and a region of phosphorus called the phosphate group. There are four types of nitrogenous bases: adenine (abbreviated as A), thymine (abbreviated as T), guanine (abbreviated as G) and cytosine (abbreviated as C).

The nitrogenous bases in DNA pair together, A with T and C with G, to form base pairs that appear as horizontal bars in DNA models. Each nitrogenous base also attaches to a deoxyribose and a phosphate group, which appear as twisting vertical strands called backbones in DNA models. In this way, nucleotides form a spiral called a double helix. The sequence of the bases in the double helix determines the information available to develop and maintain an organism, including its unique combination of traits.

DNA is the foundation of life because it can replicate, or make copies of, itself. When cells divide, a new cell contains an exact copy of the DNA from the old cell so it can function correctly. To create this copy, the new cell follows the pattern set in each strand of the double helix to duplicate the sequence of base pairs.

What Is the Total Length of Human DNA?

Human DNA is approximately an average of 6 feet, 6 inches in total length. There are roughly 3 billion base pairs in this length, and it is divided into 23 chromosomal pairs. The length of human DNA and its compact home in the nucleus of cells is comparable to fitting 24 miles of thread into a single tennis ball. Each chromosome is a different length, according to the Human Genome Project. Individual chromosomes are made up of between 50 million and 300 million base pairs.

The base pairs that form human DNA are made of pairs of adenine and thymine or guanine and cytosine. These pairs create the roughly 30,000 genes contained in the human genome.

What Is the Function of DNA in the Human Body?

The function of deoxyribonucleic acid (DNA) is to give genetic instruction to organic beings. DNA stores information to tell cells how to function, passing it on to the next generation of life through cells. It also helps in development.

In humans, half of the DNA for a child comes from the father and half from the mother. It is able to replicate itself for new cells because of its double helix structure. Each nitrogen base on the DNA strand is only able to pair with one other nitrogen base; therefore, when it splits, the DNA knows what to pair with each nitrogen base to complete a new strand.

How Much DNA Is in a Typical Human Cell?

The human genome present in the nucleus of nearly all cells within the body is composed of 3.2 billion base pairs. If unwound, this DNA would stretch to about 6 feet.

All cells except red blood cells contain a copy of the human genome within the nucleus. The genome consists of 3.2 billion base pairs, which code for approximately 70,000 genes that instruct the cell to make proteins. Most genetic information, about 98 percent, is known as non-coding DNA and does not code for proteins. DNA is arranged in a helical form that is tightly condensed into chromatin, which is stored within chromosomes. Humans have two copies, one from each parent, of 23 different chromosomes.