genetic comparisons Flashcards
1
Q
what helps scientists determine evolutionary relationships between species?
A
comparing the DNA and proteins of different species.
2
Q
how can genetic diversity within or between species be measured?
A
- comparing mRNA base sequences
- comparison of DNA base sequences, DNA hybridisation
- comparison of amino acid sequences, immunological comparisons of proteins.
3
Q
describe the process of comparing DNA/mRNA base sequences.
A
- use of computer software to compare DNA/mRNA base sequences.
- similar sequences suggest organisms are closely related
(this is DNA hybridisation)
4
Q
describe the process of DNA hybridisation.
A
- DNA from 2 species is heated to break the hydrogen bonds between DNA nucleotide bases to split the two strands.
- the DNA from both species is mixed.
- the DNA mix is cooled and hydrogen bonds form between complementary bases, forming a hybrid.
- the more complementary bases (more hydrogen bonds) the more closely related its species are.
5
Q
describe the process of comparing amino acid sequences.
A
- amino acid sequence is coded for by genes.
- similar nucleotide sequences mean similar genes, so more closely related species.
6
Q
describe the immunological comparisons of proteins (process)
A
- blood (containing protein) from species A is injected into species B.
- species B makes antibodies for the blood protein from species A.
- blood serum from species B (containing the antibodies) is mixed with blood taken from species C.
- antibodies respond to any corresponding antigen in the blood of species C and a precipitate forms.
- the stronger the precipitate, the more closely related species A and species C are.
7
Q
explain how comparing DNA, mRNA and amino acid sequences can indicate relationships between organisms within a species and between species.
A
- the more differences in sequences, indicates more distantly related.
- as mutations increase over time, the more mutations cause changes in amino acid sequences.
