Investigating diversity Flashcards
(7 cards)
How were early estimates of genetic diversity made?
Early estimates of genetic diversity were made by looking at the frequency of medsurable or observable characteristics.
What has replaced the early methods of estimating genetic diversity?
Advances in gene technology has caused this method to be replaced by direct study of base sequences of DNA or mRNA, or by the study of the amino acid sequence of the proteins encoded by DNA and mRNA.
How can you tell how closely related two species are?
You can see how closely-related two species are by comparing base sequences of DNA or mRNA.
How can you investigate diversity within a certain species?
Comparing base sequences of DNA or mRNA can also be used to investigate diversity within a certain species as individuals of the same species have the same genes but different alleles. However, most variation within a species is a combination of both genetic and environmental factors.
How does evolution occur?
Evolution occurs because of random mutations in genetic material. The more distantly-related two species, the more time has elapsed
since they had a common ancestor meaning the more opportunities for
mutations to occur. Therefore, the more sequence differences, the more distantly-related.
What are the issues with comparing the base sequences of DNA and mRNA, and comparing the amino acid sequence?
Two species may have the same amino acid sequence but different DNA base sequences because the genetic code is degenerate. Therefore, protein comparisons are less useful when comparing closely-related organisms.
Mutations that do change the amino acid sequence must be subtle, as larger changes would greatly change the tertiary structure, meaning that the protein would be dysfunctional. A dysfunctional protein is often a major disadvantage to a cell, meaning that the mutation dies out with the cell.
You have to find a protein common to both organisms.
A single protein is only coded for by a single gene (Not by the whole DNA base sequence) so only gives us an insight into a fraction of the entire genome of an organism.
How can you investigate diversity?
Take random samples of a population. Collect your data (e.g. measure size of the tree). Calculate a mean. Calculate the standard deviation of that mean.
This only works for continuous variation (which has a numerical value). Continuous variation shows a normal distribution when medsuring a given trait within a population.
