DNA, The Building Block of Everything

Why is every living thing different from every other? To answer that, we need to look at the molecule that carries the instructions for building and running a body: DNA.

What is DNA?

DNA — deoxyribonucleic acid — is a long molecule made of building blocks called nucleotides, arranged in a specific sequence that encodes the genetic instructions for a living organism. There are four nucleotide bases: adenine (A), thymine (T), guanine (G) and cytosine (C). A always pairs with T, and G with C, forming the rungs of DNA's famous double helix.

If it helps, think of DNA as a reference library rather than a blueprint — it contains instructions that are read selectively, at different times, in different cell types.

The human genome contains around 3 billion base pairs and roughly 20,000 protein-coding genes. Almost every cell in your body carries a complete copy.

From DNA to a working body

Genetic information is expressed through proteins, which do most of the actual work in the body. The process has two stages:

Transcription — a section of DNA is copied into a related molecule, messenger RNA (mRNA)
Translation — cellular machines called ribosomes read the mRNA and assemble amino acids into a protein in the specified order

Those proteins then form structures, catalyse reactions, transport oxygen, contract muscle and regulate essentially every process in the body.

What makes your DNA unique

Any two unrelated people share roughly 99.9% of their DNA sequence. Differences lie in that remaining fraction — which, across 3 billion base pairs, still amounts to millions of individual variations. These influence everything from eye colour to how you metabolise medication.

Identical twins are the exception, beginning life with essentially identical DNA — though even they accumulate small differences over time.

Not all DNA codes for proteins

Only around 1–2% of the human genome codes for proteins. The rest was once dismissed as "junk DNA", but much of it is now known to be functional — regulating when and where genes are switched on and off. Which genes are active in a cell is what makes a liver cell different from a neuron, despite both carrying identical DNA.

DNA damage and repair

DNA is constantly damaged — by UV radiation, tobacco smoke, certain chemicals, and ordinary errors during cell division. Your cells have sophisticated repair machinery that corrects the overwhelming majority of this damage.

When repair fails, a mutation persists. Most mutations are harmless, occurring in regions where they make no difference. Some are harmful: mutations accumulating in genes controlling cell growth are central to how cancers develop. And some are beneficial — variation is the raw material of evolution and the reason populations can adapt at all.

It is worth distinguishing inherited variants, present from conception in every cell and passed to children, from acquired mutations that arise in specific cells during life and are not inherited.

Why this matters for your health

Understanding your genetic variation can indicate predisposition to certain conditions, how you metabolise nutrients, and how you may respond to some medicines. But it is one input among many — lifestyle, environment and chance all shape health outcomes, usually more than any single variant does.

Testing with Rightangled

Rightangled's DNA tests examine genetic markers relating to health, nutrition and medication response, and our blood tests measure what is happening in your body right now. Results are reviewed by our clinical team, which includes GPhC-registered independent prescribers, with medical oversight from our doctor, Dr Abdullah.

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