DNA Technology, Classification and Diversity Flashcards
How was the genetic diversity of a species estimated before gene technologies.
Genetic diversity was previously estimated by looking at the frequency of measurable or observable characteristics in a population. As different alleles determine different characteristics, a wide variety of each characteristic indicates a high number of different alleles and therefore a high genetic diversity.
How can immunological comparisons help to determine the relatedness of two species?
They can test how similar the proteins of two species are. Similar proteins will bind the same antibodies. If antibodies from one species recognise the protein of another species, it’s likely those species are closely related.
Explain how gene technologies allow us to measure genetic diversity.
Genetic diversity is the number of different alleles in a population. Scientists can use gene technologies to compare DNA base sequences of the same gene. This allows them to find out how many alleles of that gene there are in a population. Scientists can also compare the mRNA and amino acid sequences produced by a gene to determine the number of alleles in a population.
Suggest an advantage of using gene technologies to measure
genetic diversity compared to previous methods.
E.g. gene technologies allow us to measure genetic diversity directly, which is more accurate and allows better comparison of genetic diversity between species than estimates based on the frequency of characteristics.
The table on the right shows part of the amino acid sequence of the same protein in four species of animal. Which species (B-D) is likely to be the least closely related to Species A? Explain your answer.
Species C is likely to be the least closely related to species A. This is because species C has three differences in its amino acid sequence compared to species A, whereas species B and D both have only two differences.
The table below shows the percentage similarity of DNA between three different species. Below are three possible phylogenetic trees based on the data in the table. Which tree most accurately represents the evolutionary relationship indicated by the data shown in the table? Explain your answer.
Tree 3 most accurately shows the evolutionary relationship indicated by the data. This is because species B and C are likely to be more closely related to each other than they are to species A, since they have a higher percentage similarity in their DNA base sequences. This suggests they share a more recent common ancestor with each other than they do with species A (which is what Tree 3 shows).
