2. molecular homology: case for
The sequence of amino acids in hemoglobin is very
similar in chimpanzees and humans.
Neo-Darwinists say the best explanation for this
similarity is that chimpanzees and humans are
descendants of a common ancestor.
3. molecular homology: case for
As proteins evolve over time, their amino acid
sequences have changed a little bit at a time.
The more time they have had to change, the more
different they will appear from one another.
By comparing the differences between the sequences
of the same protein in different species, evolutionary
biologists can determine when the two species split off
from their common ancestor and began to evolve
independently.
4. molecular homology: case for
online resources
http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_08
http://www.pbs.org/wgbh/evolution/educators/lessons/lesson3/act2.html
http://www.pbs.org/wgbh/evolution/library/04/4/l_044_02.html
http://www.nap.edu/openbook.php?record_id=6024&page=17
http://evolution.berkeley.edu/evolibrary/article/evo_17
http://www.darwinismrefuted.com/myht_of_homology_04.html
5. molecular homology: a reply
Critics of Neo-Darwinism argue that it should not be
surprising that hemoglobin in different organisms are
similar in sequence and structure, because they are
performing the same function.
Molecular similarities may reflect common functions.
6. molecular homology: a reply
If Darwin’s Tree of Life is correct, then we should
expect that different types evidences would all point to
the same tree.
Many scientists argue that this is often not the case.
A family tree based on anatomy may show one pattern
of relationships, but a tree based on DNA may show
quite another.
7. molecular homology: a reply
For example, if we look at
mitochondrial cytochrome
b gene produces a tree in
which cats and whales are in
the order of Primates.
8. molecular homology: a reply
But, if you analyze
the anatomy of
each, a different
tree emerges. The
cats belong to the
order of Carnivora,
and whales to
Cetacea, neither
being a Primate.
9. molecular homology: a reply
But, if you analyze the
anatomy of each, a
different tree emerges. The
cats belong to the order of
Carnivora, and whales to
Cetacea, neither being a
Primate.
10. molecular homology: a reply
If all of these organisms really did evolve from a single
common ancestor, only one of the trees can be right.
Critics point out that the real problem is that Universal
Common Descent is wrong.
In other words, the reason that the trees don’t agree is
that the organisms do not share a common ancestor.
Some evolutionary biologists agree. Carl Woese from the
University of Illinois is one. He thinks that biology should
abandon the idea of common descent. He says that life
probably had multiple, independent starting points.
11. molecular homology: a reply
Biologist used to think that the genetic code was the
same for everyone.
This means that genes code for the same protein in
almost identical ways.
For example, the code for hemoglobin is the same code in
humans, monkeys, lions, tigers and bears.
12. molecular homology: a reply
Is it the same?
No! Since 1985 scientists have discovered 18 different
genetic codes. Many are very different from the standard
code.
The standard code has 3 different mRNA stop codons:
UGA, UAA, and UAG.
A codon is a group of 3 base pairs that match with a tRNA.
A stop codon, tells the cell to stop building the protein - it is
now finished.
13. molecular homology: a reply
Of the 18 other codes discovered, they only have one
stop codon, UGA.
The other 2 codons code for a certain amino acid.
If an organism was going to change from the standard
code to the new one, it is hard to imagine how.
Changing to this new code would cause the cell to
produce useless strings of extra amino acids when it
should have stopped the protein production.
Having extra amino acids in a protein is a serious
problem - the protein will not function properly.
14. molecular homology: a reply
This leaves the organism with 2 options:
1. simultaneously get a new set of genetic information
that matches the new code (Nearly all biologist think
that this is highly unlikely)
2. Die
15. molecular homology: a reply
resources
Evolution Exposed
by Roger Patterson
Speciation - page 57-67
Homology - page 68-72
Fossils (transitional) - page 73-74
Molecular Homology - page 74-75
Embryology - page 95-96
Refuting Evolution
by Jonathan Sarfati
The Politically Incorrect Guide to Darwinism and
Intelligent Design by Jonathan Wells
