DNA technology, classification and diversity

genome sequencing

advances in genome sequencing have meant that the entire base sequence of an organisms DNA can be determined.

the DNA base sequence of one organism can then be compares to the DNA base sequence of another organism, to see how closely they are relates.

closely related species will have a higher percentage of similarity in their DNA base order.

comparing amino acid sequence

proteins are made of amino acids. the sequence of amino acids in a protein is coded by the base sequence in DNA

related organisms have similar DNA sequences and so similar amino acid sequences in their protein.

comparing amino acid sequence eg cytochrome c

is a short protein should in many species, the more similar the amino acid sequence os cytochrome C in two different species, the more closely related the species are likely to be.

immunological comparisons

similar proteins will also bind the same antibodies.

eg if antibodies to a human version of a protein are added to isolated samples from some other species, any protein thats like the human version will also be recognised by that antibody

gene technologies have

changed the way genetic diversity is assessed

high genetic diversity

since alleles determine characteristics a wide variety of each characteristic in a population indicates a high number of different alleles

how were early estimates of genetic diversity made?

by looking at the frequency of measurable or observable characteristics in a population

gene technologies have now been developed that allows us to measure genetic diversity directly for example

* different alleles of the same one will have slightly different DNA base sequences. comparing the DNA base sequences of the same gene in different organisms in a population allows scientists to find out how many alleles of that gene there are in the population
* different alleles will also produce slightly different mRNA base sequences, and may produce proteins with slightly different amino acid sequences, so these can also be compared

new technologies can all be used to

a more accurate estimates of genetic diversity within a population. they also allow genetic diversity of different species to be compared more easily