Why is DNA so important?
Put simply, DNA contains the instructions necessary for life.
The code within our DNA provides directions on how to make proteins that are vital for our growth, development, and overall health.
Keep reading to discover more about the structure of DNA, what it does, and why it’s so important.
What is DNA?
DNA stands for deoxyribonucleic acidTrusted Source. It contains units of biological building blocks called nucleotides.
DNA is a vitally important molecule for not only humans but also most other organisms. DNA contains our hereditary material and our genes, the things that make us unique.
What is the structure of DNA?
A collection of nucleotides makes a DNA molecule. Each nucleotide contains three components:
a phosphate group
a nitrogen base
The sugar in DNA is called 2-deoxyribose. These sugar molecules alternate with the phosphate groups, making up the “backbone” of the DNA strand.
Each sugar in a nucleotide has a nitrogen base attached to it. There are four different types of nitrogen bases in DNA. They include:
The two strands of DNA form a 3-D structure called a double helix. When illustrated, DNA looks like a spiral ladder in which the base pairs are the rungs, and the sugar-phosphate backbones are the legs.
Additionally, it’s worth noting that the DNA in the nucleus of eukaryotic cells is linear, meaning that
the ends of each strand are free. In a prokaryotic cell, the DNA forms a circular structure.
What does DNA do?
DNA contains the instructions that are necessary for an organism to grow, develop, and reproduce. These instructions exist within the sequence of nucleotide base pairs.
DNA helps your body grow
Your cells read this code three bases at a time to generate proteins that are essential for growth and survival. The DNA sequence that houses the information to make a protein is called a gene.
Each group of three bases corresponds to specific amino acids, which are the building blocks of proteins. For example, the base pairs T-G-G specify the amino acid tryptophan, while the base pairs G-G-C specify the amino acid glycine.
Some combinations, like T-A-A, T-A-G, and T-G-A, also indicate the end of a protein sequence. This tells the cell not to add more amino acids to the protein.
Proteins contain different combinations of amino acids. When placed together in the correct order, each protein has a unique structure and function within your body.
How do you get from the DNA code to a protein?
First, the two DNA strands split apart. Then, special proteins within the nucleus read the base pairs on a DNA strand to create an intermediate messenger molecule.
This process creates the messenger molecule RNA (mRNA). mRNA is another type of nucleic acid. It travels outside the nucleus, serving as a message to the cellular machinery that builds proteins.
In the second step, specialized components of the cell read the mRNA’s message three base pairs at a time and work to assemble a protein, amino acid by amino acid. This process is called translation.
DNA in health, disease, and aging
The complete set of your DNA is called your genome. It contains roughly 3 billion basesTrusted Source, 20,000 genes, and 23 pairs of chromosomes.
You inherit one half of your DNA from your father and one half from your mother. This DNA comes from the sperm and egg, respectively.
Genes make up very little of your genome — only 1 percent. The other 99 percent helps regulate things like when, how, and in what quantity your body produces proteins.
Scientists are still learning more and more about this “non-coding” DNA.
DNA damage and mutations
The DNA code is prone to damage. According to estimates, tens of thousands of DNA damage events occur every day in each of our cells. Damage can occur due to errors in DNA replication, free radicals, and exposure to UV radiation.
Your cells have specialized proteins that can detect and repair many cases of DNA damage. There are at least fiveTrusted Source major DNA repair pathways.
Mutations are permanent changes in the DNA sequence. Changes in the DNA code can negatively impact how the body produces proteins.
Mutations can also lead toTrusted Source the development of cancer. For example, if genes coding for proteins involved in cellular growth mutate, cells may grow and divide out of control. Some cancer-causing mutations are heritable, while others develop through exposure to carcinogens like UV radiation, chemicals, or cigarette smoke.
But not all mutations are bad. Some are harmless, while others contribute to our diversity as a species.
Changes that occur in at least or more than 1 percentTrusted Source of the population are called polymorphisms. Examples of some polymorphisms are hair and eye color.
DNA and aging
Unrepaired DNA damage can accumulate as we age, helping to drive the aging process.
Something that may play a large role in the DNA damage associated with aging is damage due to free radicals. However, this one mechanism of damage may not be sufficient to explain the aging process. Several factors may also be involved.
One theoryTrusted Source as to why DNA damage accumulates as we age concerns evolution. It’s thought that DNA damage is repaired more faithfully when we’re of reproductive age and having children. After we’ve passed our peak reproductive years, the repair process naturally declines.
Another part of DNA that may be involved in aging is telomeres. Telomeres are stretches of repetitive DNA sequences at the ends of your chromosomes. They help protect DNA from damage, but they also shorten with each round of DNA replication.
Studies associate telomere shortening with the aging process. Some lifestyle factors such as obesity, exposure to cigarette smoke, and psychological stress can also contributeTrusted Source to telomere shortening.
Where is DNA found?
DNA is present in our cells. The exact location of it depends on the type of cell.
Humans and many other organisms have eukaryotic cells. This means that their cells have a membrane-bound nucleus and several other membrane-bound structures called organelles.
In a eukaryotic cell, DNA is within the nucleus. A small amount of DNA is also in organelles called mitochondria, which are the cell’s powerhouses.
Because there’s a limited amount of space within the nucleus, the body condenses the DNA into packages. There are several different stages of packaging. The final products are the structures that we call chromosomes.
Organisms like bacteria are prokaryotic cells. These cells don’t have a nucleus or organelles. In prokaryotic cells, DNA resides in the middle of the cell, called a nucleoid, coiled tightly.
What happens when your cells divide?
Your body’s cells divide as a normal part of growth and development. Each new cell must have a complete copy of DNA when this happens.
To achieve this, your DNA must undergo a process called replication. When this occurs, the two DNA strands split apart. Then, specialized cellular proteins use each strand as a template to make a new DNA strand.
Following replication, there are two double-stranded DNA molecules. One set will go into each new cell when division is complete.
DNA is pivotal to our growth, reproduction, and health. It contains the instructions necessary for your cells to produce proteins that affect many different processes and functions in your body.
Because DNA is so important, damage or mutations can sometimes contribute to disease development. However, it’s also important to remember that mutations can be beneficial and contribute to our diversity.
Last medically reviewed on February 11, 2022
How we reviewed this article:
Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.
Feb 11, 2022
Jill Seladi-Schulman, PhD
Medically Reviewed By
Stacy Sampson, D.O.
Copy Edited By
Aug 14, 2019
Jill Seladi-Schulman, PhD
Medically Reviewed By
Alana Biggers, MD, MPH
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Medically reviewed by Stacy Sampson, D.O. — By Jill Seladi-Schulman, Ph.D. — Updated on Feb 11, 2022