10. Determining relatedness of a species Flashcards
Name two molecules that could be compared to show phylogenic relationships
DNA sequence and amino acid sequence
If two species are closely related they will have more/less differences in their sequences of amino acids.
less
If two species are not closely related they will have more/less differences in their sequences of amino acids.
more
When identifying from a phylogenic tree the two species most closely related the success criteria is …?
Comparative term
Mutations accumluate overtime
Quoted differences
Why are we able to use the number of mutations in DNA to indicate evolutionary relationships
Because mutations accumulate over time, Then the more mutations that have occurred indicates a longer time period since divergence
What could we compare in terms of DNA?
Chromosomes
Diploid number.
Gene loci.
Why is it more accurate to use DNA sequence in preference to Amino Acid sequence.
DNA has three times the amount of information and will identify when a silent mutations has occurred.
What are the steps of DNA hybridisation?
The sources of DNA are heated to 90oC to break the hydrogen bonds and separate the strands.
These are then mixed together.
The sample is cooled.
This will form some hybrid DNA.
The sample is then reheated to measure the temperature required to break the hydrogen bonds between the hybrid strands.
Measure the temperature that is required to break the hybrid DNA into single strands.
A higher temperature will be required to break the hybrid DNA back into single strands between more closely related species.
If two species were closely related what would we expect to see in the result of their DNA Hybridisation?
A higher temperature will be required to break the hybrid DNA back into single strands between more closely related species.
If two species were not closely related what would we expect to see in the result of their DNA Hybridisation?
A lower temperature will be required to break the hybrid DNA back into single strands between less closely related species.
Describe structural morphology
Looking for similarities between the physical features
of different species. This means that it can be used evidence for the relatedness between species.
Compare mt.DNA with nuclear DNA as evidence for relatedness of humans
mtDNA is inherited from the mother/down maternal line whereas nuclease DNA is inherited from both parents.
mtDNA has no crossing over whereas nuclear DNA has undergone crossing over.
mtDNA could be advantageous to track the inheritance down the maternal like as there is no crossing over OR there is more copies of this in a cell as there are many mitochondria.
Nuclear DNA could be advantageous as it contains the whole genome/DNA from both parents OR as there is more DNA/bases/introns and exons there is more information.
