Variation Flashcards
Define variation
Variation is the differences between individuals of the same species.
What is mutation?
Mutation is a change in a gene or chromosome.
What is gene mutation?
A change in the base sequence of DNA
For example;
5 TGAC 3 - 3 GTCA 5 might become something like; 5 GGTC 3 - 3 GACC 5
How are new alleles formed?
Through mutation! (It changes everything)
When do chromosome mutations occur?
When cell division fails to work with complete accuracy.
Yes, when this happens the consequences are often serious.
What are the symptoms of sickle-cell anaemia?
Anaemia (duh.)
What two factors increase the rate of mutation?
Ionising radiation and some chemicals.
What radiations can cause mutation?
Gamma, ultraviolet and X-radiation (these cause mutations by damaging DNA)
What chemicals cause mutation?
Tars in tobacco smoke, high concentration of some preservatives, some plant control hormones.
Which people with the allele for sickle-cell anaemia are resistant to malaria?
People who are heterozygous for the disease
What is discontinuous variation mostly caused by?
Genes alone.
Example: A, B, AB, and O blood groups in humans
What are two factors that cause phenotypic variation?
Genetic and environmental factors
