Mutations

Gene

A small section of DNA that controls a specific characteristic by coding for a specific protein

Bases

A specific organic section of a nucleotide that contains nitrogen, there are four different types of bases in a DNA polymer

C, G, A and T

The letters that represent the four different types of bases found on a strand of DNA

Nucleotide

A small structural unit of DNA, composed of a common sugar and phosphate group with one of four different bases attached to the sugar

Repeating nucleotides

The DNA polymer is made up of repeating nucleotide units with different arrangements of the bases C, G, A and T

Sequence of three bases

The genetic code for an amino acid also called a codon or triplet, this arrangement of three bases leads to the formation of one specific amino acid

Amino acids

The building blocks of proteins, the sequence of amino acids determines the shape and function of the overall protein

Proteins

Building blocks of cells and tissues, made up by a specific order of amino acids which in turn is coded for by a specific sequence of DNA

A change in the specific sequence of DNA

Can affect the sequence of amino acids produced, which can subsequently affect the overall shape and function of a protein

Protein chain

When a chain of amino acids is completed it folds up to form a specific shape, enabling proteins to do their jobs as enzymes, hormones or structural collagen

Mutation

A change in the sequence of DNA that can result from copying errors during cell division or exposure to ionising radiation, chemicals or viruses

Types of mutation

Base substitution, insertion, deletion or inversion

Base insertion or deletion

Where a single base is added or removed in a DNA sequence, which could lead to the translation of a different amino acid

Base substitution or inversion

Where a single base is swapped or where the order of several bases change, which could lead to the translation of a different amino acid

Insignificant effect of mutations

Most mutations have no effect on the shape of the protein and even if the shape changes slightly it may not affect the protein's function

Significant effects of mutations

Mutations can have a significant effect in rare cases, an altered enzyme may not fit a binding substrate or an altered structural protein may lose its strength

Genetic variants

Changes in DNA as a result of mutation which can alter the sequence of base triplets and therefore alter the sequence of amino acids in coding DNA

Phenotype

The observable properties or characteristics of an organism

Non-coding DNA

Regions of DNA that do not code for proteins, but are responsible for gene expression and can switch genes on and off

Effect of genetic variants on non-coding DNA

Altering the sequence of non-coding DNA could result in genes that are typically off being switched on or vice versa