Determining Relatedness Between Species

Question 1

Homology

Answer 1

existence of shared ancestry between a pair of structures, or genes, in different taxa.

Used to determine how similar the DNA base sequence and amino acid sequences corresponding of proteins are between two species.

Question 2

DNA hybridisation

Answer 2

1. DNA from 2 species is extracted and heated to separate the double-stranded DNA to single-stranded DNA
2. The single-strand of DNA from one species is mixed together with the strand from another species and cooled down
3. Both strands are then heated once again, causing them to bind together.
   - Each degree of difference in temperature is proportional to the percentage of different bases in the hybrid DNA (e.g. separates at 77 = 10% of DNA doesn’t match)
   - The more base-pairs that complement one another explains that those species are more related and thus have a stronger hydrogen bond, in turn requiring more heat to break them apart again

Question 3

Mitochondrial DNA

Answer 3

Biological clock, passed from mother to child. Causes mutations to occur regularly.

MtDNA is used for analysis of ancient organisms because it’s more easily recovered than nuclear DNA.