Biology AS AQA Unit 2 Genetic Diversity

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  • Created on: 02-09-13 12:50
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Genetic Diversity
The DNA which determines the variety of the proteins that makes up each organism.
DNA that codes for one or more polypeptides is called a gene.
The alleles of the gene determine the specific characteristic of the gene. E.g. eye colour.
Organisms therefore differ in alleles, and not their genes. (Same species=same genes)
The greater number of different alleles in a species, the greater the genetic diversity. (Wider
range of alleles= wider range of characteristics.)
The greater the genetic diversity, the more likely a species will be able to adapt to
environmental change.
Therefore, similar climates hold similar genes.
Selective Breeding
Identifies individuals with desired characteristics and using them to parent the next
In this way unwanted alleles are bred out of the population.
The variety of alleles becomes restricted.
Commonly found in cattle, plants etc.
Founder Effect
Occurs when a few individuals from a population colonise a new region.
The few individuals have very few alleles with them which may not be representative of the
larger population.
Therefore the new population has very little genetic diversity.
Often seen when new volcanic islands came out of the sea.
The new population is less able to adapt to changing conditions.
Genetic Bottleneck
The dramatic drop in a species numbers cause a few alleles to remain with the survivors.
The survivors therefore posses a smaller variety of alleles and hence their genetic diversity
will be less.


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