Evidence for Evolution - Protein Sequences

How do we determine sequence of amino acids in proteins

using modern biochemical techniques

Amino acids in same species, similar species, different species

In same species: identical protein sequences

In different species: have different amino acids or arranged in a different order

species more closely related have more similarities in their amino acid sequences

Using protein sequence to determine evolution from common ancestor

Degree of difference between proteins enables estimate of the amount of evolution that has taken place since 2 species developed from common ancestor. Longer period of time involved, greater number of amino acids that are different.

what is a ubiquitous protein?

 One of a group of proteins that appears to be in all species from bacteria to humans

Purpose of ubiquitous protein:

• perform very basic but essential tasks that all organisms require for life.

• Carry out same functions no matter where they are found.

characteristic of ubiquitious protein (not purpose)

are completely independent of an organism’s specific function or environment it lives in

examples of ubiquitious proteins

cytochrome c, haemoglobin

purpose of cytochrome c

Performs essential step in production of cellular energy & appears to have changed very little over millions of years of evolution

structure of cytochrome

Contains 104 amino acids, 37 of these have been found at same positions in every sequenced cytochrome C molecule, regardless of the species

what does prescence of the ubiquitious protein cytochrome C indicate about evolution?

Strongly suggest descended from ancestral cytochrome C molecule found in a primitive microbe from more than 2000 million years ago

what is bioinfomatics?

the use of computers to describe the molecular components of living things. It is a multidisciplinary field that provides evolutionary evidence by combining areas of biological science, computer science, engineering, statistics and applied mathematics

How do researchers compare genomes using bioinfomatics?

Genes and other biological features in DNA sequences need to be identified, a process termed annotation. 

Annotation is made possible because genes have recognisable start & stop codons.