Classification Using Dna Or Proteins Flashcards
What is evolution ?
Gradual change in species over time.
What 3 advances in technology is helping us to classify organisms more accurately?
Genome sequencing
Comparing amino acid sequence
Immunological comparison
Genome.
Complete set of genes in a cell
What genome sequencing ?
It has meant entire base sequences of an organisms DNA can be determined.
DNA base sequence of one organism can be compared to DNA base sequence of another organism so see how closely related they are.
Closely related species have higher % of similarity in their DNA sequence.
How closely related are humans and chimps ?
They share around 94% of the same DNA
Example of genome sequencing
It has clarified relationship between skunks and numbers if the mustelidae family (weasels)
Skunks were classified as part of the Mustelidae family until their DNA sequence was revealed to be significantly different to members of that family.
Reclassified - mephitidae
What do we do in comparing amino acid sequence ?
Because the sequence of amino acids in a protein is coded for by the base sequence in DNA.
Related organisms will have similar DNA sequences and so similar amino acids sequences in proteins.
Example of comparing amino acid sequence
Cytochrome C is a short protein in many species.
More similar amino acid sequence of cytochrome C is in 2 different species, the more closely related.
What is immunological comparison
Using antibodies to determine how similar proteins are.
As similar protein will also bind to same antibody
Example of immunological comparison
If antibodies to a human version of a proteins are added to an isolated sample from another species.
Any protein like that of the human species will be recognised by that Antibody.
How is another way to determine how similar 2 proteins are ?
As proteins which bind anything will form a precipitate in solution.
The more antibodies the proteins binds the more precipitate will form.
The table shows the % similarity of DNA using DNA sequencing analysis between several species of bacteria.
Describe table
Species A and B have the highest percentage of DNA in common with each other (86%) than they do with other species like C or D.
This means A and B are more closely related to each other than they are to C and D.
Diagrams shows the DNA sequence for gene X in three different species.
Describe and explain
13 differences between base sequence in species A and C.
Only 2 differences between base sequences of species A and B.
A and B are more closely related than A and C
What are antibodies often linked with fluorescent protein ?
Allows antibodies to be detected once they have bound to a protein
