What Are the Subunits of DNA?

Four nucleotides make up DNA.
••• Comstock/Comstock/Getty Images

Deoxyribonucleic acid is present in the nucleus of every cell in our body in compactly folded up forms called chromosomes. The four building blocks that make up the DNA are repeated to form a long chain. They encode a vast amount of information, ranging from eye color to the predisposition to a disease.

Subunits of DNA

Nucleotides are the subunits of DNA. The four nucleotides are adenine, cytosine, guanine and thymine. Each of the four bases has three components, a phosphate group, a deoxyribose sugar and a nitrogen-containing base. The nitrogenous base attached to the bases may be a double-ringed purine or a single-ringed pyrimidine. Adenine and guanine are purine bases, while cytosine and thymine are pyrimidine bases. These four nucleotides, referred to as the A, C, G and T are the building blocks of DNA.

Arrangements of Subunits

The four nucleotides join with each other and form what is famously known as the DNA ladder. Hydrogen bonds form only between a purine and a pyrimidine nucleotide base, so the adenine always binds to thymine and cytosine to guanine to form a long chain. Further linking on the DNA ladder occurs by the bonding of the sugar of one nucleotide to the sugar of the adjoining nucleotide by a phosphate group. The sugar phosphate bonding forms the sides of the DNA ladder and is responsible for the twist in DNA.

Human DNA

The Human Genome Project determined the sequence of the three billion bases present in human DNA. The arrangement of these bases encode for the 20,000 different genes present on 23 pairs of chromosomes. The sequence of the bases reveals information that scientists use to diagnose diseases, find cures and even fight crime.

An Interesting Fact

A chain formed by joining the DNA from every cell in the human body can make approximately 70 round trips from the earth to the sun.

Related Articles

What Causes the Double Helix to Twist in a DNA Picture?
What Are Some Characteristics of DNA?
How Does DNA & RNA Differ?
Nucleic Acid Facts
What Does Chemical Analysis Reveal About DNA?
What Are Some Characteristics of DNA?
What Types of Molecules Catalyze RNA Splicing?
What Are the Two Major Components of an Atom?
Three Components of ATP
What Are Twisted Strands of DNA in the Nucleus of the...
The Three Ways That a Molecule of RNA Is Structurally...
How to Make a DNA Model Using Pipe Cleaners
What Are the Two Major Functions of Nucleic Acid in...
What Causes the Double Helix to Twist in a DNA Picture?
What Is the Relationship Between Nitrogen Bases & the...
What Is the Difference Between a Nucleotide & a Nucleoside?
How to Get a tRNA Sequence from a DNA Sequence
What Are the Functions of mRNA & tRNA?
What Is a Extra Ring of DNA in Bacteria?