Before we dive into the science of telomeres and telomerase, it is important to understand how they fit in human biology.

Cells are the basic building block of your body; it has trillions of them. Each cell contains a nucleus, the command centre for the cell. This is where most of your deoxyribonucleic acid, or DNA, resides. DNA is your hereditary material.

Genes are made up of DNA. Each chromosome contains many genes.

Your DNA is stored as code made up of four chemical bases. Human DNA is made up of approximately 3 billion bases — more than 99% of these bases are identical in all people. It is the remaining ‘less than 1%’ that accounts for your unique physical characteristics.

These DNA bases pair up with each other to form units called base pairs. Each base is also attached to a sugar and a phosphate molecule. These are the building blocks of what is called the double helix, or human DNA.

DNA is the building block for genes, which are the basic physical and functional units of heredity.

The National Human Genome Research Institute (NHGRI) defines the gene as:

“… the basic physical unit of inheritance. Genes are passed from parents to offspring and contain the information needed to specify traits. Genes are arranged, one after another, on structures called chromosomes. A chromosome contains a single, long DNA molecule, only a portion of which corresponds to a single gene. Humans have approximately 23,000 genes arranged on their chromosomes.”

Each human cell has these 23,000 genes that carry in it your unique DNA in the form of a chemical code, called the genetic code.

The Anatomy of the Chromosome

That brings us to chromosomes. The nucleus of every cell in the human body normally has 46 chromosomes, made up of 23 pairs. One of each pair comes from the mother and the father. In essence, chromosomes are packed with the detailed blueprints — DNA and genes — of who we are and what makes us unique.

You began your life as a single cell, the pairing of egg and sperm. As you began to grow in the womb, this single cell divided into two, then four, then eight. And so you multiplied until you entered the world nine months later as a new-born. The process of this cell division is called mitosis.

Mitosis is the fundamental process for life. During mitosis, all parts of the cell duplicate, including the 46 chromosomes. The result is two daughter cells that, in a perfect world, are identical to its parent.

It is this process of duplication — mitosis — where we introduce telomeres. How do telomeres take part in mitosis and how critical a role do they play? Stay tuned.