What is DNA?
DNA stands for deoxyribonucleic acid. It is a complex, long-chained molecule comprising biological units called nucleoids. It contains the instructions needed to create proteins and some molecules which are necessary for the development and functioning of the body. 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.
Where is DNA found?
DNA is present in the cells and its exact location depends on the type of cells. There are two types of cells:
Structure of DNA
To understand the functions of DNA, we first need to understand its structure. The DNA structure is described as a double helix. This structure can be thought of as a twisted ladder. The complete set of DNA is called your genome. The DNA molecule is composed of units called nucleotides, and each nucleotide is composed of three different components:
- Phosphate groups
- Nitrogen bases.
The basic building blocks of DNA are nucleotides, which are composed of a sugar group, a phosphate group, and 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. The sugar and phosphate groups link the nucleotides together to form each strand of DNA. There are four nitrogen bases present in DNA, namely:
- Adenine (A)
- Thymine (T)
- Guanine (G)
- Cytosine (C)
DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule to form a nucleotide. Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases, determines the information available for building and maintaining an organism.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell. Another thing to note is 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 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 the division is complete.
Now let us understand the purpose of DNA.
What is the role of DNA in the body?
DNA is the fundamental determinant of how the body functions and defines the basic blueprint for all life. Understanding the functions of DNA has helped revolutionize the investigation of disease pathways, diagnose genetic disorders, and formulate new drugs.
Some major functions of DNA are:
- DNA transfers hereditary information between two generations and defines your unique features. When different genes are “read,” different proteins are made – each with its own
function. For instance, some proteins are used as enzymes or hormones to regulate specific processes in the body. Other proteins are used as building blocks in the body or serve to transport things in the bloodstream. The cell nucleus contains a lot of proteins, too: Some help to read the DNA code, while others help to support the structure of the DNA.
- DNA helps your body grow. DNA helps in the production of proteins. Our cells read three bases at a time to generate proteins that are essential for the growth and survival of our body. Each group of three bases corresponds to specific amino acids, which are the building blocks of proteins. 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.
DNA damage and mutations
Due to errors in DNA replication, free radicals, and exposure to UV radiation, 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.
Mutations are permanent changes in the DNA sequence. Changes in the DNA code can negatively impact how the body produces proteins. If the protein doesn’t work properly, diseases can develop. Some diseases that occur due to mutations in a single gene include cystic fibrosis and sickle cell anaemia.
Mutations can also lead to 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.
Something that may play a large role in the DNA damage associated with aging is damage due to free radicals. 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.
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.