Variation Flashcards
What is variation?
The differences within a species.
What two types of variation are there?
Genetic or environmental.
What is genetic variation within a species caused by?
It is caused by organisms having different alleles (versions of genes) which can lead to differences in phenotype (the characteristics an organism displays).
What else causes genetic variation, other than organisms having different alleles?
- New alleles arising through mutations.
- Sexual reproduction, as it results in alleles being combined in different ways in offspring.
What is environmental variation?
Variation caused by the environment (the conditions in which organisms live).
What are mutations?
Changes to the base sequence of DNA.
What happens when a mutation occurs within a gene?
It results in an allele (different version) of the gene.
What are neutral mutations?
Mutations that don’t have any effect on the phenotype of an organism.
What can a single mutation rarely do?
Have a big effect on phenotype.
What is an example of a single mutation having a big effect on phenotype?
Cystic fibrosis.
