G C T A T A G C T A G C T A G C T A A mutation is a change in the DNA sequence. This may occur by an ‘insertion’, ‘deletion’ or ‘substitution’ of a base pair. T A E.g. Insertion

G C T A T A G C T A G C T A G C T A T A E.g. Deletion A mutation is a change in the DNA sequence. This may occur by an ‘insertion’, ‘deletion’ or ‘substitution’ of a base pair.

G C T A T A G C T A G C T A G C T A T A E.g. Substitution A mutation is a change in the DNA sequence. This may occur by an ‘insertion’, ‘deletion’ or ‘substitution’ of a base pair.

Changing the base sequence in DNA results in new alleles, which could cause changes to phenotypes. This explains variation within and between populations. If a mutation occurs during meiosis then it is inherited. G C T A G C T A T A G C T A T A G C T A Thousands of base pairs Amino acids Protein Phenotype T A

Mutations can be harmful, neutral or beneficial to an organism. BeneficialNeutralHarmful Mutations that increase an organisms chances of survival and reproduction -Bacteria that develop resistance to antibiotics. -The gene that produces an enzyme (protein) to metabolise lactose during human adulthood. -A gene involved in multiple eggs released during ovulation. Mutations that neither increase or decrease an organisms chances of survival and reproduction. -Green eyes. -Colour blindness. -Chin dimple. Mutations that decrease an organisms chances of survival and reproduction. -Genes that increase cancer risks. -Being born without arms or legs (is this harmful to humans today, do you think?)

Adaptations are aspects of the phenotype that allow the organism to survive and live successfully in its particular environment. StructuralPhysiologicalBehavioural Relating to the organism’s structure. The opposable thumb – allowing grip and the use of many tools. Relating to the organism’s body chemistry or processes. Lactose tolerance – to produce the enzyme lactase to break down lactose (sugar) in milk and milk products as adults. Relating to the organism’s behaviour. Grasping response – a clinging reflex in babies. Suckling response – a suckling reflex in babies.

Note: Behaviour can be innate (genetically determined and inherited) or learnt (not genetically determined and therefore not inherited). Most human behaviour is learnt, while a lot of behaviour of other animals is innate. Left: Innate behaviour known at the withdrawal reflex. Right: Learnt behaviour through observation and mimicking.

The selection by environmental factors of individuals with successful phenotypes to survive and reproduce. This is the basis of evolution.