Genetics Basics


Our bodies are made up of millions of cells. Each cell contains a complete copy of our genetic information. Our genetic information contains the instructions for our body to develop, grow and work. Our genetic information is commonly referred to as our genes and can be found in sections of our DNA (deoxyribonucleic acid). DNA can be found in all parts of your body, including blood and saliva. The sum of all your genes or genetic information is called your genome.

On left hand side is a person, a magnifying glass zooms into show a cell. A magnifying glass zooms in on the cell to show chromosomes. A magnifying glass then zooms in on the chromosomes to show DNA

We share parts of our genetic information with our blood relatives. This includes parents, grandparents, siblings, and children.

Changes (or variants) in genetic information can help explain differences in how people look (such as eye colour, hair colour, or height) or change the chance of someone developing health conditions in the future.

Genome (Library)

A complete copy of all our genetic information is called a genome. Our genome is like a library that contains all the different instruction manuals that tell our body how to grow and work.

Blue 1900s style building with a sign out front saying "Library"

Chromosomes (Bookshelves)

We get half our genome from our mother and the other half from our father. This means all our cells have two copies of every gene (instruction manual), as we receive one copy from each parent. While the genes are very similar there can be small differences in the instructions of our genes.

Our complete genome (our library) is made up of 46 chromosomes (bookshelves) that hold all our genetic information. These bookshelves are arranged into 23 pairs. We all have two copies of each chromosome (two copies of each bookshelf), meaning we have two copies of every gene (two copies of every instruction manual).

Two book shelves in two different colours. Showing we get half our chromosomes from each parent.

Genes (Instruction Manuals)

Our genes hold all the genetic information that act as the instruction manual for our body. Different genes hold the instruction for eye colour, how tall we will be, or how our heart will grow.

A book open to a page, on the page the letters A, T, C and G repeat in a random order.

Bases (Letters)

The letters that make up the spelling of our instruction manuals are called bases.

Genetic Change (Variant)

A genetic variant refers to a gene that has a difference in the way the bases are arranged.

There are four arrow shapes in different colours. Each shape contains either the letter A, T, C or G.

More detail about Genetic Changes (Variants)

We can think about genetic variants using the example below:

Consider the sentence "Mum fed the cat"

In some cases we can have a spelling change in our genes which may change how our body reads the instructions. These spelling changes are called a gene variant.

Most spelling changes in our genes have no impact on our health and our body can read the instructions as normal. These changes have no impact on our health, but are unique changes that make up who we are.

A slight change of spelling may not effect the meaning of the sentence. "Mom fed the cat". This is an example of benign variation.

In some cases a spelling change can impact the body’s ability to read the instruction. This can lead the gene to stop working or change the instructions of the gene. This type of spelling change can lead to health conditions, such as cardiomyopathy.

Some spelling changes impact the meaning of the sentence. "Mum fed the rat". This is an example of pathogenic variation.

More information about genetics: