BIOCHEMICAL EVIDENCE AND PHYLOGENY

1
BIOCHEMICAL EVIDENCE AND PHYLOGENY
2
I. Biochemical Evidence (more)

• A. All organisms use DNA as their hereditary
  material and, together with RNA, use this as a
  way to generate needed proteins.
• B. The fact that organisms all contain the same
  bases for DNA and RNA coupled with the fact that
  all organisms contain the same 20 amino acids is
  evidence for common ancestry.

3
C. Similarly, the fact that proteins are used as
structural units and enzymes in all living
organisms further supports the idea of common
ancestry. D. The structural similarity of some
universal proteins like cytochrome c and
haemoglobin suggests decent from a common gene
(from a common ancestor).
4
E. Gorilla haemoglobin and human haemoglobin only
differ by one amino acid. F. Using the variations
in specific molecules (like proteins) one can
make a phylogenetic (evolutionary) tree. G. A
phylogenetic tree can track divergences from
common ancestors and show patterns of development.
5
(No Transcript)
6
(No Transcript)
7

• H. Techniques now exist that allow us to
  determine differences between nucleotide and
  amino acid sequences.
• Most of these differences are due to random
  mutations and mutation rates are often known.
• J. If the mutation rate is known and so is the
  number of differences, the age of divergence for
  that gene can be calculated.

8
K. Mutation rate 1,000 years differences
10 so, 1000 x 10 10,000 years